02 Jaydeva Thesis

1. INTRODUCTION

The groundnut (Arachis hypogaea L.) is a valuable food and

oilseed crop. It is commonly called the king of vegetable oil seeds or

poor man’s nut. It belongs to the family Papilionaceae, largest and most

important of the three divisions of leguminosae. Groundnut appears to

have originated in the South America i.e. North-West of Brazil, the

secondary centre of its cultivation is in Africa (Vavilov, 1951).

The botanical name for groundnut, Arachis hypogaea Linn., is

derived from two Greek words, Arachis meaning a legume and hypogaea

meaning below ground referring to the formation of pods in the soil.

Different cultivars of groundnut are broadly classified into the following

two groups.

1. Virginia – having bunchy, semi-spreading or spreading growth

habit

2. Spanish – having bunch growth habit

The groundnut is a slow growing annual geocarpic plant with a

central upright stem. The plants grow from 30 to 60 centimeter high and

produced angular, hairy stems with spreading or erect branches. The

spreading varieties have pods scattered along their prostrate branches

from base to top whereas, the pods are found in clusters at the base of the

plant of the erect or bunch type. The flowers are borne at the axils of the

leaves, either above or below the ground, it has a relatively deep tap root

system with a well developed lateral root system.

Groundnut is the 13th most important food crop of the world. It is

the world 4th most important source of edible oil and 3rd most important

source of vegetable protein. Groundnut seeds contain high quality edible

oil (50 per cent), easily digestible protein (25 per cent) and carbohydrates

(20 per cent) (Weiss, 1983).

Globally, 50 per cent of groundnut produce is used for oil

extraction, 37 per cent for confectionary use and 12 per cent for seed

purpose. In India, 80 per cent of the total produce is used for oil

extraction, 11 per cent as seed, 8 per cent for direct food uses and 1 per

cent is exported (www.icrisat.org). Groundnut haulms (vegetative plant

parts) provide excellent hay for feeding livestock. They are rich in

protein and have better palatability and digestibility than other fodder.

Groundnut cake obtained after oil extraction, is used in the animal and

poultry feeds. It is also used as organic manure and is rich source of

nitrogen (7.6 per cent). Groundnut cotyledons contains 20 per cent

carbohydrates and is excellent source of thiamine and vitamin E and

small quantities of vitamin A, C and D (Weiss, 1983). Groundnut oil is

used in medicine as it is highly nutritive and laxative too. The magnitude

of per capita oil consumption in India is very low. On an average an

Indian consumes only 6 kg of oil which is less than half of the world’s

average of nearly 13 kg/year.

Groundnut is grown on 26.4 million ha worldwide with a total

production of 36.1 million metric tonnes and an average productivity of

1.4 metric t ha-1 (www.icrisat.org) and is grown in nearly 100 countries.

The major groundnut producing countries from the world are China,

India, Nigeria, USA, Indonesia and Sudan. Developing countries account

for 96 per cent of the global groundnut area and 92 per cent of the global

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production. Asia accounts for 58 per cent of the global groundnut area

and 67 per cent of the groundnut production with an annual growth rate

of 1.28 per cent for area, 2.00 per cent for production and 0.7 per cent for

productivity. It ranks first among the oil seed crops of India, which is

largest groundnut producing country accounting for 33 per cent of world

production and 40 per cent of the area. In India major groundnut

producing states are Gujarat, Andhra Pradesh, Tamil Nadu and

Maharashtra (www.faostat.org). It occupied an area of 7.92 million ha

with it’s annual production of 7.02 million metric tonnes, with an average

productivity of 1052 kg ha-1 (Anonymous, 2007). In Maharashtra 3.2

lakh ha area is under groundnut cultivation in kharif season with the

production of 2.8 lakh tonnes and an average productivity of 1147 kg ha-1

(Anonymous, 2007), while in summer season the crop occupied an area

of 0.86 lakh ha with the production of 1.09 lakh tonnes and an average

productivity of 1364 kg ha-1 (Anonymous, 2007a).

There are several reasons for the low yield of groundnut in India

and Maharashtra and efforts are being made to remove the bottleneck

limiting the production.

Groundnut varieties have a wide variability in their germination

behaviour. The cultivated groundnut Arachis hypogaea L. has two sub-

species : subspecies hypogaea (Virginia Bunch and Virginia Runner

varieties) and subspecies fastigiata (Spanish and Valencia varieties). The

kernels of Spanish and Valencia bunch types are usually non-dormant,

whereas those of Virginia bunch and runner varieties are dormant (Rao,

1976). The non-dormant character in Spanish and Valencia bunch type is

undesirable for groundnut cultivation in summer season where at harvest

stage of the crop rains are invariably received and cause heavy losses of

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http://www.faostat.org/

produce by way of sprouting of pods in the field. It is more problematic

in soil areas where moisture retention capacity is high. A loss of 20-50

per cent in bunch groundnut pod yield has been reported due to in situ

germination (Nagarjun and Radder, 1983a). In the Spanish bunch type,

cultivars possessing 3-4 weeks dormancy will be able to save the field

losses due to in situ sprouting when the mature crop is caught in untimely

rains. Thus the non-dormant nature of bunch groundnuts, besides

reducing the yield, also deteriorates seed and oil quality. Seed

availability is also reduced because of field sprouting.

Seed dormancy is a physiological inactive stage or resting stage of

seed. When viable seed fails to germinate under favourable conditions is

called seed dormancy. Dormancy is an important factor in commercial

groundnut production. It can be beneficial when dormancy prevents

mature seeds from sprouting before harvest. It can be detrimental when

dormancy reduces stand or hampers taking a second crop immediately

after harvest.

Lack of dormancy in bunch types has been described as an inherent

property of seed and does not primarily depend on soil conditions (Hull,

1937; Lin and Lin, 1971a and Weiss, 1983). Occurrence of seed

dormancy is reported on a few dormant Spanish bunch strains (Patil,

1973; Patil and Chandramouli, 1978) but periodical data on extent of

dormancy present during the storage period is lacking for most of the

varieties developed at various centres. Hence a first step towards

introducing dormancy into the recommended high yielding varieties, it

was considered useful to study the promising varieties of Spanish bunch

groundnuts to know the extent of dormancy present in them.

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The search for investigation of non-conventional methods of

inducing dormancy in bunch types to save the produce and to retain the

seed quality against the field sprouting are of greater importance. For

inducing seed dormancy in groundnut number of methods have been

developed. There are some chemicals which are capable of altering the

seed dormancy. Among those, treatment with foliar application of maleic

hydrazide at different stages of crop growth. Maleic hydrazide a growth

inhibitor has been successfully used to control sprouting of tubers, roots

and bulbs during storage. The key idea in the use of growth regulators is

to control some aspects of growth, regulate the balance between source

and sink, which is the final analysis results in the higher yield of desired

product. The information on the choice of proper concentrations of MH

and its time of application on the locally available groundnuts is lacking.

Keeping this in view an attempt has been made to study the

feasibility of inducing dormancy with various concentrations of maleic

hydrazide in groundnut genotypes viz., TG-26, TAG-24 and SB-XI, the

present investigation "Induction of seed dormancy in summer groundnut'

was undertaken with the following objectives.

1. Standardization of concentrations of maleic hydrazide for

induction of dormancy in summer groundnut.

2. Determination of dormancy period of groundnut varieties under

study.

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2. Review of Literature

Although groundnut (Arachis hypogaea L.) is an important oil seed

crop of summer season, it is being widely grown under irrigation during

summer season. The area under summer irrigated groundnut is fast

increasing though it's yields are very low as compared to USA and China.

Several reasons could be ascribed to its low productivity of which

nearly 20 per cent loss in the field is by the in situ germination due to lack

of dormancy (Anonymous, 1979). Hence, there is a need to identify

sources of short duration with certain period of dormancy to minimize

yield losses due to in situ germination (Ashok Kumar, 1989 and Patil et

al., 1991).

The Review of Literature pertaining to the aspects of induction of

seed dormancy in summer groundnut is very meager. However, an

attempt has been made to review the available literature on this aspect

and the same is presented in this chapter.

2.1 Types of dormancy

Basically seed dormancy indicates the inability of the seeds to

germinate even under favourable conditions. It is fairly obvious that

more than one cause might be responsible for the dormancy of a seed.

In a broad view, two types of dormancy can be distinguished i.e.

(1) "Innate' dormancy where the seeds will not germinate even under

favourable conditions and (2) Imposed dormancy where seeds will not

germinate when conditions are unfavourable. Several forms of innate

dormancy have been recognized. Seeds may fail to germinate because of

impermeable seed coat to water (Matthews, 1976).

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2.2 Factor influencing seed dormancy in groundnut

Seed dormancy in groundnut is controlled by many features.

Different causes of seed dormancy in groundnut have been reported by

many workers.

2.2.1 Presence of inhibitors and ratio between growth promoters to

inhibitor

In recent years the presence of naturally occurring growth

inhibitors have received increased attention which are supposed to play

an important role in induction and termination of dormancy. Amen

(1968) has developed a general model for seed dormancy based on the

assumption that the state of dormancy is determined by the balance

between growth inhibitors and growth promoters.

Nagarjun and Gopalkrishnan (1958) reported that non-dormant

seeds of TMV-2 groundnut contained a water soluble growth promoting

hormone and the seed extract induced root initiation in the dormant seeds

of TMV-3 groundnut. The physiological studies done by Sreeramulu and

Rao (1971) revealed that the water soluble hormone was indole acetic

acid which has root inducing activity. This auxin was noticed at high

levels in the embryonic axis and seed coat of non-dormant seed.

2.2.2 Genetic aspects of dormancy

Dormancy like most of the physiological phases in seed, is initially

determined by the genetic make up of the seed and varies largely among

species and even within a species. The variation may be expressed in the

strain which is used for the improvement of varieties.

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Hull (1937) reported that dormancy in groundnut is an inherited

character and the rest period extended even upto two years in some

varieties. John et al. (1950) pointed out that dormancy is an inherent

property of Virginia groundnut. The trait dormancy was found to be

partially dominant over the trait non-dormancy. Genetic differences in

seed dormancy between strains with different botanical groups have been

demonstrated for several investigators (Ramachandran et al., 1967 and

Lin and Lin, 1971b).

2.2.3 Mechanical restriction of the seed coat

Hardness or impermeability of seed coat is said to be one of the

many causes for dormancy. This causes physical restriction to the

exchange of gas and water which are essential for the initiation of

germination process. The inheritance of hard seed coat varies among and

within the species. This dormancy is also mediated by environment

prevailing during seed ripening period.

Significant morphological differences in the testa among the

different cultivars of groundnut were reported. The seeds of ‘starr’

variety showed relatively thin compact testa while that of Virginia type

was thicker (Gulek et al., 1977).

2.2.4 Presence of ethylene

Ethylene was involved in the normal regulation of seed dormancy

(Toole et al., 1964). Ketring and Morgan (1969) reported that the

embryonic axis of non-dormant seeds of peanut actively produced

ethylene during germination, where as ethylene production was low in

dormant seeds.

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2.3 Maleic hydrazide for inducing dormancy

Maleic hydrazide (diethanolamine salt of 1,2-dihydroxy-3,6

pyridazine-dione), a growth inhibitor has been successfully used to

induce dormancy and thus to reduce sprouting losses in potato, sugarbeat,

onion, carrot and rice. However, the information available on the effect

of MH in inducing seed dormancy in groundnut is meager and

inconclusive.

Schoene and Hoffmann (1949) reported the growth inhibiting and

herbicidal properties of maleic hydrazide. The effectiveness of MH in

preventing sprouting of potato tuber was first reported by Zukel (1950).

Naylor and Davis (1950) found that MH was uniformly effective as

a growth inhibitor both for dicotyledonous and monocotyledonous plants.

Pre-harvest foliar application of MH was found to be effective in

reducing the storage losses in sugarbeat (Wittwer and Hansen, 1951 and

Mikkelesen et al., 1952).

Wittwer and Paterson (1952) and Rao and Wittwer (1955) have

successfully used MH as pre-harvest foliar spray on potato to prevent

sprouting of tubers in the field before harvest.

Krishnamurthy (1969) reported that induction of seed dormancy in

two varieties of bunch groundnut (Spanish improved and TMV-2) with

the foliar application of MH. Karivaratharaju and Rao (1972) suggested

the use of MH-30 for pre-harvest foliar application to reduce the losses

due to viviparous germination in rice as the harvesting period coincides

with rainy season in coastal regions.

Vaithialingam and Rao (1973) reported that induction of dormancy

in TMV-2 bunch groundnut by the foliar application of MH-30, in a field

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trial conducted at Coimbatore. Nagarjun and Radder (1983) reported that

foliar application of MH could induce dormancy in bunch type of

groundnut variety in the field trials.

Gupta et al. (1985) reported that induction of dormancy in bunch

type of groundnut variety T-64 by the foliar spray of MH in the field

trials conducted at Allahabad. Appalanavidu and Murthy (1961) reported

that the maleic hydrazide (MH) was found to be successful in inducing

dormancy in tubers, bulbs and seeds and also in increasing the yield of

Ragi.

2.4 Maleic hydrazide concentrations for induction of seed

dormancy

The concentration of MH is important in obtaining the higher

degree of dormancy.

Wittwer et al. (1950) have suggested the use of 500 ppm MH to

induce dormancy in carrot and onion as 2500 ppm did not reduce

sprouting significantly than 500 ppm concentrations. Zukel (1950)

reported that a single foliar spray of 2500 ppm MH was effective in

inducing dormancy in potato tubers. Hansen (1949) stated that pre-

harvest foliar spray of MH at 2500 ppm concentration was effective in

reducing sprout growth in sugarbeet.

Paterson et al. (1952) revealed that a concentration of 500 or 1000

ppm MH was sufficient to reduce the sprouts in Irish cobbler and Pontiac

varieties of potato. But spraying MH at higher concentration (2500 ppm)

induced prolonged dormancy (four to seven weeks). Thus, they have

suggested that any degree of dormancy could be induced with adjustment

in spraying time and concentration of the chemical.

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Appalanaidu and Murthy (1961) reported that the percentage of

germination in ragi was reduced when MH sprayed to the crop at the rate

of 5 and 10 lb per acre after 30 and 45 days of sowing respectively.

According to Randhawa and Nandpuri (1966) reported that the

lower concentration of MH was less effective than higher concentration

in reducing the sprouts in onion bulbs during the storage. They have

noticed maximum dormancy in onion when MH was sprayed at 1000

ppm prior to harvest.

Krishnamurthy (1969) conducted the pot culture experiment and

revealed that foliar spray of 500 ppm MH at 15 and 25 days prior to

harvest induced dormancy in two varieties of bunch groundnut (Spanish

improved and TMV-2). The number of sprouts reduced from 13.3 to 1.8

in Spanish improved and 17.5 to 5.8 in TMV-2. In a field trial he

observed the induction of dormancy in Spanish improved with 200, 400

and 600 ppm concentrations of MH sprayed at 75, 81 and 106 days after

sowing. Sprouting was 10.3, 12.7 and 10.5 per cent due to 200, 400 and

600 ppm concentrations respectively as compared to that of unsprayed

control (25.6 %). On the basis of this he recommended to use 200 ppm,

as the higher concentrations further did not induce dormancy appreciably.

Vaithialingam and Rao (1973a) reported that foliar application of

MH induced dormancy irrespective of the stage of application. The MH

sprayed @ 5000 ppm at 70 DAS, 15000 ppm at 80 DAS and 10,000 ppm

at 90 DAS induced dormancy ranging from 30 to 40 per cent. At 30

DAH, the dormancy effect was greatly reduced.

Vaithialingam and Rao (1973b) studied the induction of seed

dormancy in non-dormant groundnut. The MH-30 application as foliar

spray was done at 0, 5000, 10000, 15000, 20000, 25000 and 30000 ppm

at 70, 80 and 90 DAS. Revealed that irrespective of stages of application,

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all the treatments reduced the germination of the non-dormant seeds

severely and increased the total free amino acid content while inducing

dormancy.

Nagarjun et al. (1980) conducted a field trial with bunch groundnut

to study the optimum stage and concentrations of MH for foliar spray on

the seed quantity and subsequent growth of seedlings. They reported that

there was a reduction in seed moisture content due to foliar spray of 250

ppm MH in the early stage of crop growth (60 days). However, the MH

application did not show any effect on seed purity, seed viability and seed

protein content and seedling growth, while MH at concentrations greater

than 500 ppm increased oil content significantly.

Nagarjun and Radder (1983a) observed that foliar spray of maleic

hydrazide (MH) after 60 days of sowing was found to be superior in

inducing seed dormancy compared to later stages of MH application (75

and 90 days of crop growth). The concentrations ranging from 250 to

1000 ppm remarkably enhanced the seed dormancy to the extent of 60-80

per cent. However, application of MH in lower concentrations (250 ppm)

but at an early stage of crop growth (60 days) was found to be as good as

that of higher concentrations in inducing seed dormancy. Reduction in

moisture content and the rate of catalase enzyme activity were in

association with increase in the degree of induced seed dormancy.

Gupta et al. (1985) have reported that a foliar spray of MH @ 15 x

103 or 20 x 103 ppm applied to groundnut variety (T-64) at 90 days after

sowing induced the seed dormancy.

Bhapkar et al. (1986) revealed that a foliar application of MH-30 at

different concentrations viz., 5000 ppm at 70 DAS, 10000 ppm at 90 DAS

induced seed dormancy ranging from 30 to 40 per cent. Abrar and

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Jadhav (1991) reported that the seed dormancy period was increased from

5 to 25 days in cv. PI-139915 and PI-169292 by 200 ppm MH applied as

foliar spray one month before harvesting.

Jagatap (2000) studied the induction of seed dormancy in bunchy

groundnut genotypes viz., RHRG-12, TAG-24, RHRG-16 and SB-XI. He

revealed that seed dormancy could be induced upto 30, 10, 30 and 20

days, respectively by foliar application of MH @ 250 ppm than other

concentrations of MH applied viz., 500 and 750 ppm. He also noticed

that reduction in seedling vigour index and seedling dry weight due to

dormancy induction. The 100 kernel weight (g) was increased and seed

viability remains unaffected due to MH spray @ 250, 500, 750 ppm in all

the genotypes.

Nautiyal (2004) conducted an experiment at NRC, Junagarh

(Gujarat) in groundnut on induction of seed dormancy in non-dormant

groundnut cultivars using foliar spray of MH at various concentrations

and reported that foliar spray of malic hydrazide @ 1000 ppm, 60 days

after crop emergence was found to be superior in inducing dormancy in

Spanish groundnut cultivars.

2.5 Seed dormancy period in bunch groundnut varieties

Kramer and Kozlowski (1960) reported that the dormant nature of

seed appears to vary according to the geographic spread of species or

genera. Gavrielith (1962) reported that the dormancy period of a variety

changes from year to year.

Varisai and Dorairaj (1968) screened 206 groundnut varieties

under irrigated condition for dormancy. Only 6 bunch varieties had a

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dormancy period of about 15-20 days. None of the bunch varieties

studied was completely dormant.

Bailey et al. (1972) reported that the Spanish and Virginia

genotypes showed as much as 70 per cent seed dormancy and one

Virginia genotype as little as 3 per cent. Narasimha Reddy and Swamy

(1977) studied gibberellins and germination inhibitors in viable and non-

viable seeds of peanut and reported that the more acidic and basic

germination inhibitors were present in viable seeds. Loss of viability is

associated with presence of inhibitors and absence of gibberellin like

substances.

Reddy et al. (1985) studied 17 groundnut varieties belonging to

Spanish and Valencia botanical groups reported that the derivative of the

cross, J-11 x Robout-33-1 was found to possess seed dormancy for a

period of about 35 days.

Pandya and Patel (1986) studied seeds of 4 Virginia and 73

Spanish bunch varieties and 5 Spanish x Virginia hybrids for percentage

germination after 3-50 days of storage at room temperature. Virginia

types and their crosses, particularly G-201, ICGS-6, Robout-33-1 and

(TMV 10 x Robout-33-1)-2, were more dormant than most of the Spanish

types tested. Among the Spanish varieties, RSHY-6, ICGS-21, ICGS-30,

ICGS-57, TG-9 and TG-17 were identified as sources of dormancy for

breeding.

Kamala et al. (1987) reported that the germination percentage (pre-

harvest sprouting) was scored 105-140 days after sowing in 15 bunch

varieties of 105 days duration. TG-9, TG-17 and TG-15 showed the

lowest germination percentage (8-10 % after 140 days), followed by

CGS-1-19 and Dh-8. Reddy et al. (1987) observed that CGC-7, also

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known as CGS-1-19 possesses a seed dormancy period of 5 weeks. The

F8 of CGC-7 shows differential germination, indicating variation for

dormancy period.

Kumar et al. (1991) reported that the cultivars of subsp fastigiata

generally lacked dormancy while those of subsp hypogea were

characterized by long dormancy periods.

Varman and Raveendran (1991) observed that varieties of bunch

groundnut Arachis hypogaea subsp. Fastigiata, show little seed

dormancy, with a result that 20-50 per cent of pods germinate in situ due

to rains at the pod maturity stage. With a view of identifying seed

dormancy, some 55 high yielding genotypes of subsp. Fastigiata were

grown in the field during kharif 1988 at the agricultural research Station,

Aliyarnagar. Pods were collected at maturity and evaluated for seed

dormancy. ICGV-86011 possessed seed dormancy, with pods sprouting

18 days after harvest compared with 2-4 days for the other genotypes.

Seed dormancy was also observed in pods of ICGV-86011 subjected to

water stress at pod maturity.

Nautiyal et al. (1993) reported that the degree of maturity, position

of kernel in the pod and the storage period all had a confounding

influence on the seed dormancy.

Anonymous (1995) reported that relationship between dormancy

and viability, fourteen dormant and non-dormant groundnut genotypes

were raised during the rabi-summer 1995 and pods after through drying

were placed in cotton bags and stored inside the galvanized bins. The

viability of the seeds was monitored at different storage periods.

Dormant genotypes maintained higher germinability than the non-

dormant types. The germinability of the dormant genotypes viz.,

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ICGS011, ICGS-44, TG-22 was > 99 per cent even after eight months

storage.

Venu et al. (1995) studied that the relationship of seed moisture

content with dormancy and seedling vigour in Spanish and Virginia

genotypes of groundnut. It was observed that the whole seed dormancy

was higher in both Spanish and Virginia types as compared to embryo

dormancy. The genotype Dh-3-30 indicated dormancy period of 20-30

days with whole seeds but did not show embryo dormancy, indicating the

presence of dormancy factors in seed coat. On the contrary, the removal

of seed coat in ICGS-30, EDR, Bidar local and Mardur local improved

the germination but failed to release the dormancy completely, thereby

indicating that the factors responsible for dormancy might be residing

both in seed coat and embryo. The embryo of Dh-3-30 which had no

dormancy exhibited higher seedling vigour index values than the whole

seeds of the same genotype as well as whole seeds and embryo’s of the

other dormant genotypes.

Nautiyal et al. (1996) screened about 200 Spanish germplasm lines

for fresh seed dormancy during rabi/summer 1995. Revealed that

genotypes showed variation in germination percentage. During

rabi/summer 1995, the crop was harvested at 110 DAS and most of the

genotypes showed more than 60 per cent fresh seed dormancy, finally

they concluded that the dormancy period of most of the genotypes was

laid between 30-40 days.

Anonymous (1999) reported that three mutants of cv. Girnar-1

(non-dormant) namely PBS-30021, 30109 and 30163 were found to

possess fresh seed dormancy about 1-4 weeks.

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Joshi and Nautiyal (1999) conducted an experiment at NRC,

Junagarh (Gujarat) on groundnut to screen about 180 Spanish type

germplasm accessions alongwith the cultivars having fresh seed

dormancy viz., ICGS-11 and ICGS-44 as checks, were screened both

under field and laboratory conditions. They reported that the genotypes

NRCG-7197, NRCG-7186 and NRCG-835 had 23, 24 and 28 per cent

pods were sprouted, respectively in the field. They concluded that these

genotypes had 8, 1 and 5 per cent fresh seed dormancy.

Upadhyay and Nigam (1999) conducted an experiment to

determine the fresh seed dormancy index (FSDI) percentage in 200

groundnut germplasm accessions and 21 cultivars belonging to the

Spanish group and revealed that, large variation in pod loss due to in situ

sprouting of seed, the fresh seed dormancy was found among the

accessions and cultivars. Fresh seed dormancy index varied from 2 per

cent in chico to 88 per cent in ICGS-44 (check), concluded that cultivars

with an FSDI value of less than 10 per cent, showed more pod loss in situ

than the cultivars with high FSDI. Thus, pod loss due to in situ sprouting

increased with a decrease in FSDI. Cultivar SB-XI did not show any in

situ sprouting or pod loss.

Mathur et al. (2000) stated that two cultivars of groundnut viz.,

PBS-12115 and PBS-12126 were found to be higher yielder and PBS-

12115 possessed fresh seed dormancy of 21-28 days, while PBS-12126

possessed fresh seed dormancy of about 14-21 days and suggested to use

these two genotypes as donar parents for incorporation of fresh seed

dormancy in breeding programme.

Swain et al. (2001) studied 17 erect, 8 semi-spreading and 5

spreading varieties to analyse the nature of variation of seed dormancy in

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different varietal forms of groundnut and revealed that dormancy period

of the varieties ranged from 33 to 107 days. Finally they stated that TG-

26 had the longest dormancy period of 107 days.

Swain and Sahoo (2001) studied the duration of seed dormancy in

different bunch type groundnut cultivars and reported wide variation in

their duration ranging from 5.4 days to 106.6 days.

Manonmani (2002) studied both dormant and non-dormant

cultivars of groundnut, reported that dormant cultivars maintained higher

seed germinability in storage for a longer period than the non-dormant

cultivar of groundnut varieties.

Singh et al. (2002) screened 5 different cultivars of groundnut for

detection of dormancy periods, revealed that all the cultivars possess

dormancy period ranging from 4 to 5 months. Minimum dormancy of 4

months was observed in non-dormant bunch type groundnut cultivars viz.,

Chitra, Prakash and Kaushal whereas in spreading type groundnut

cultivars viz., Chandra and Amber possessed 5 months dormancy period.

The results indicated that bunch type varieties had less dormancy in

comparison to spreading type of cultivars.

Swain et al. (2002) studied a dormancy behaviour of different type

of cultivars of groundnut viz., 17 erect, 8 semi-spreading and 5 spreading

types, they reported that most erect varieties showed short to moderate

dormancy period and most semi-spreading and spreading varieties

possessed longer dormancy period coupled with strong intensity of

dormancy and seeds of kharif showed the highest degree of dormancy

followed by rabi and summer.

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Asibuo James Yaw et al. (2008) conducted an experiment at Ghana

(Africa) to determine the heritability of fresh seed dormancy in groundnut

and to transfer this trait from dormant exotic lines (ICGV-86158 and

ICGV-87388) into two non-dormant groundnut varieties (Shitaochi and

Aprewa), they reported that seed dormancy is controlled by monogenic

inheritance with dormancy dominant over non-dormant, as the results

showed that more than 90 per cent of the freshly harvested seeds of the

non-dormant parents germinated before 14 days, whereas less than 10 per

cent of the seeds of the dormant parents germinated during the same

period.

2.6 Seed mycoflora

Javeed et al. (1998) reported that different strains of fungi in 36

seed samples of groundnut varieties collected from Faisalabad, Chadwad,

Rawalpindi and Attock districts of Punjab, Pakistan and observed that

Alternaria alternata, Aspergillus flavas, Aspergillus niger, Arthrobotry’s

spp., Cephalosporium spp., Fusarium equiseti, Fusarium moniliforme, F.

solani and Rhizopus spp. were recorded at different frequencies,

groundnut varieties BC-12, B-40, BC-21 and Valencia generally had less

pathogens present on the seeds.

Rasheed et al. (2004) reported different seed borne mycoflora of 12

groundnut seed samples collected from different localities of Pakistan by

using blotter test, agar plate and deep freezing method of the 14 genera

and 28 spp. of fungi isolated, 18 fungal sp. viz., Macrophomina

phaseolina, Rhizoctonia solani, Fusarium oxysporium, Aspergillus flavus,

Aspergillus niger, were found predominant. Higher number of fungi

were isolated where blotter method was used as compared to agar plate

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and deep freezing method. Surface sterilization of seeds reduced the

incidence of A. flavus and Aspergillus niger.

El-Maghraby et al. (2007) revealed that sixty-four species and 2

vareities which belong to 19 genera of fungi were identified from 40

peanut seed samples collected from different places in Egypt by using

dilution plate method on glucose-czapek’s medium. The most frequent

genera noticed were viz., Aspergillus (21 species and 2 varieties),

Penicillium (16 species) and Fusarium (6 species) and they finally

concluded that A. flavus, A. niger, Fusarium oxysporium and Penicillium

chrysogencem were the most common fungal species associated with

groundnut seeds.

20

3. MATERIAL AND METHODS

The present investigation entitled, “Induction of seed dormancy in

summer groundnut (Arachis hypogaea L.)” was conducted during

summer 2007 season at Seed Technology Research Unit Farm,

Department of Agricultural Botany, Mahatma Phule Krishi Vidyapeeth,

Rahuri.

The details of materials used and methods adopted for these

investigations, are described in this chapter.

3.1 Preparation of land

A piece of fairly well leveled land with uniform fertility was

selected for conducting the experiment. Before laying out the

experiment, the field was brought to good tilth by ploughing once and

harrowing twice and by collecting stubbles and debris of the previous

crop.

3.2 Climatic conditions

The Mahatma Phule Krishi Vidyapeeth, Rahuri is situated between

19°47’ and 19°57’ north latitude and between 74°82’ and 74°19’ east

longitude. It is situated at about 525 meters above the mean sea level.

This tract is laying on the eastern side of the Western Ghat, falls under

rain shadow area. Climatically, this area falls in semi-arid, subtropical

zone with an annual rainfall varying from 307 to 619 mm with an average

of 525 mm which is generally received through south-west monsoon.

21

3.3 Experimental design

A separate experiment was laid out in a Factorial Randomized

Block Design with three replications. The gross plot size was 4.00 x 3.00

m2, while the net plot size was 3.8 x 2.4 m2. The row to row spacing was

30 cm, while plant to plant spacing was 10 cm (Fig. 1).

3.4 Seeds and sowing

Three groundnut (Arachis hypogaea L.) varieties viz., TG-26,

TAG-24 and SB-XI were selected for study.

Pure seeds of all these cultivars were obtained from the Groundnut

Breeders, Groundnut Research Scheme, MPKV, Rahuri (Maharashtra).

The seeds were hand dibbled at 30 x 10 cm with one seed per hill for all

varieties.

3.5 Manures and fertilizers

Farm yard manure @ 10 tonnes per hectare was uniformly spread

in the field before harrowing. The fertilizers in the form of urea, single

super phosphate were applied @ 25:50:00 kg ha-1, respectively and

gypsum was applied @ 250 kg ha-1 at the time of sowing.

3.6 Irrigations

First pre-sowing irrigation followed by second irrigation was given

immediately after sowing. Thereafter the uniform irrigation given to all

the plots as when required till harvest of the crop.

22

3.7 After care

Usual agronomic practices of groundnut cultivation including those

of its seed production were timely carried out during the growth period to

raise a good crop.

3.8 Treatment details

A) Genotypes

The pedigree and salient features of three genotypes evaluated are

as below.

Sr. No.

Genotypes Pedigree Salient features

1. TG-26 (TGS-2 x TAG-1) Spanish bunch, semi-dwarf, high harvest index

2. TAG-24 (TG-18A x M-13) x TAG-1 Spanish bunch, semi-dwarf, high yielding

3. SB-XI Ah-4218 x Ah-4354 Spanish bunch, kharif and summer base, early

B) Foliar application of maleic hydrazide (MH)

A 100 per cent maleic hydrazide in the form of powder was used

for the foliar spray. Initially 15000 ppm of MH spray solution was

prepared by adding 33.75 g of MH powder in 2.25 litre of distilled water.

Then mixture was solubalized by using KOH pellets with the help of

magnetic stirrer. The spray solution of 150, 300, 450, 600 and 750 ml for

250, 500, 750, 1000 and 1250 ppm respectively was taken, then the

volume was made upto 9 litres. The spray mixture was applied @ 500

litres per ha so as to wet the completely foliage. Care was taken while

spraying to prevent the carry over of the drift of solution to the adjoining

plots. Maleic hydrazide was sprayed at two stages of crop growth i.e. 60

23

DAS and 90 DAS with five concentrations viz., 250, 500, 750, 1000 and

1250 ppm and absolute control were given.

3.9 Harvesting

The plants were uprooted from plot area of each treatment and in

each replication separately. All dirt, impurities and immature pods were

removed and pods were taken immediately into the laboratory for further

post harvest observations.

3.10 Observations recorded

The following post harvest observations were recorded.

3.10.1 Germination percentage

For testing dormancy, the germination percentage was determined

at 5 days interval immediately after harvest. Initial germination was

recorded on very first day after harvest. Four replications of 100 seeds

from each treatment were kept for germination at 25°C temperature for

10 days using between paper method (BP). The germination percentage

was expressed on the basis of normal seedlings only as described in ISTA

rules (Anonymous, 1999).

3.10.2 Seedling vigour index - I

Ten normal seedlings from each treatment and in each replication

were selected randomly immediately after germination test. The total

root and shoot length was measured in centimeter. The average of ten

seedling was worked out for calculating the seedling vigour index.

24

The seedling vigour index I was determined by using the formula

given by Abdul Baki and Anderson (1973) as below.

Vigour index I = Average root + Average shoot x Germinationlength in cm length in cm percentage

3.10.3 Seedling vigour index – II (SDW)

The seedlings selected for calculating the seedling vigour index-I

were oven dried and the oven dry weight of these seedlings was used for

calculating the seedling vigour index - II.

Seedling vigour index II was determined by using the formula

given by Abdul Baki and Anderson (1973) as below.

Vigour index II = Seedling dry matter x Germination percentage

3.10.4 Moisture content (%)

Moisture content of seeds was determined by drying 10 gm seeds

at 103±2°C for 17 hours in hot air oven (Anonymous, 1999). The

percentage of moisture content was calculated on the wet weight basis by

following formula given by Roberts and Roberts (1972).

M2 – M3

Moisture content (%) = ----------------- x 100M2 – M1

Where,

M1 = weight of container (g)

M2 = weight of container + seed before drying (g)

M3 = weight of container + seed after drying (g)

25

3.10.5 Electrical conductivity (mmhos/cm)

Three replications each of 25 seeds were randomly selected from

each treatment and soaked in 75 ml of distilled water at 25°C for 24

hours. The solution and seeds were gently swirled for 10 to 15 seconds

prior to evaluation. The electrical conductivity of the solution was

measured by using conductivity meter having cell constant one and

expressed as mmhos/cm/g (Loeffler et al., 1988).

3.10.6 Seed mycoflora (%)

The seed health was determined by blotter test to detect the

presence of seed borne fungi of groundnut seed (Anonymous, 1999).

Three layers of blotters (size fitting to the size of petridish) soaked in

sterilized distilled water were placed in petridish. Ten seeds were placed

in each petridish at equidistance and the petridishes were kept in an

incubator 20±2°C for 7 days beneath near ultra violet light (NUV) with a

cycle of 12 hrs light and 12 hrs darkness. Three replications were

maintained. The seeds were then examined on 8 th day under stereoscopic

binocular microscope. The fungi were identified on the basis of

sporulation and their fruiting structures.

3.10.7 100 Kernel weight (g)

The observation on 100 kernel weight was taken at every 5 days

interval. One hundred seeds were randomly selected from each treatment

and in three replications. The weight of 100 kernel (g) were recorded

(Anonymous, 1999).

3.10.8 Shelling percentage

The observation on shelling percentage was taken at 0 and 65

DAH. Two hundred fifty grams of cleaned and completely dried pods

26

were weighed from each treatment in three replications and shelled.

Weight of the kernels was recorded and the shelling percentage was

worked out by using the following formula.

Weight of kernelShelling percentage = ---------------------------- x 100

Weight of the pods

3.10.9 Oil content (%)

The oil content (%) was determined by Near Infrared

Transmittance (NIT) instrument. The 250 g of groundnut seeds were

placed in an NIT inlet in three replications in each treatment. The oil

content was then expressed in percentage by weight.

3.10.10 Protein content (%)

The nitrogen percentage in the seed was estimated by modified

Kjeldhal’s method (Jackson, 1967). The gram groundnut seed sample

from each treatment in three replications was digested in digestion tubes

using 0.02 N concentration H2SO4 and 2 % Boric acid. After digestion of

sample, 10 ml of an aliquot of digested acid extract was placed in

distillation apparatus with 40 % NaOH solution. Then distillation was

carried out till all the ammonia is evolved. The distillate was titrated with

standard H2SO4 alongwith blank till the colour changes from green to red.

The nitrogen percent was worked out by using the following formula.

ml of H2SO4 ml of H2SO4 Normality Acid extract volume 100% N = for sample – for blank x of H2SO4 x 0.014 x --------------------------- x ----------------------

Aliquot taken (ml) wt. of sample (g)

The protein in the seeds was calculated by multiplying the nitrogen per

cent with a factor 5.46 (Tai and Young, 1974).

27

3.10.11 Tetrazolium test (TZ test)

Viability of groundnut seeds were determined at 0 DAH by

tetrazolium test as described by Lakon, 1949. The 100 seeds from all the

treatments were conditioned over night in distilled water in four

replications. The seed coats were removed by using forceps and needles

by lifting up at the pointed end and tearing in a spiral manner. The

prepared seeds were deeped in 1.0 per cent aqueous solution of 2,3,5-

triphenyl tetrazolium chloride and placed in a small beakers covered with

lid. The beakers were placed in a dark, warm place (20°C) for three

hours. The seeds were evaluated as viable or dead on the basis of

staining pattern in embryo followed by cotyledons.

3.10.12 Sound mature kernel (%)

The observation on sound mature kernel (%) was taken at 65 DAH.

The groundnut kernels were drawn randomly and weighed about 250 g in

three replications in each treatment. The fully matured, uniform sized

seeds were separated by discarding undersized, broken, immature and

shriveled seeds with the use of purity test board. The sound mature

kernel percentage was worked out by using the following formula.

Mature dry kernelSound mature kernel percentage = ------------------------------ x 100

Total weight of kernel

3.11 Statistical analysis

The data on laboratory determination were analysed by using

FCRD method as described by Snedecor and Cochran (1967).

28

4. EXPERIMENTAL RESULTS

An experiment was conducted at Seed Technology Research Unit,

MPKV, Rahuri, to study the effect of spraying of different concentrations

of Maleic Hydrazide (MH) on induction of dormancy in bunchy

groundnut during summer, 2007. The varieties used were TG-26, TAG-

24 and SB-XI. The MH concentrations used were 250 ppm, 500 ppm,

750 ppm, 1000 ppm and 1250 ppm. The spraying was done at 60 and 90

days after sowing. The induction of dormancy was tested by testing the

groundnut seed germination and other seed quality parameters every after

5 days interval after harvest upto 65 days. The dormancy was supposed

to be broken down by considering the Minimum Seed Certification

Standards (MSCS) for germination (70 %) in groundnut. The results

obtained from the study are presented in this chapter.

4.1 Germination percentage

4.1.1 Effect of maleic hydrazide

The data on effect of MH concentrations on induction of dormancy

are presented in Table 1 and Fig. 2.

The significantly highest germination was recorded in control seed

sample (without MH spraying) during all the periods of testing,

irrespective of genotypes. The MH sprayed @ 250 ppm recorded the

mean germination of 43, 61, 65 and 67 per cent at 0, 5, 10 and 15 DAH,

respectively, irrespective of genotypes. At 20 DAH the germination was

74 per cent which is above the MSCS. The MH sprayed @ 500 ppm

recorded the mean germination of 38, 54, 58, 58 and 66 per cent at 0, 5,

29

10, 15 and 20 DAH, respectively, irrespective of genotypes. At 25 DAH

the germination recorded was 70 per cent which is above the MSCS. The

MH sprayed @ 750 ppm recorded the mean germination of 27, 50, 54,

56, 63 and 69 per cent at 0, 5, 10, 15, 20 and 25 DAH, respectively,

irrespective of genotypes. At 30 DAH the germination recorded was 72

per cent, which is above the MSCS. The MH sprayed @ 1000 ppm

recorded the mean germination of 13, 39, 47, 48, 57, 64, 65, 69 and 69

per cent at 0, 10, 15, 20, 25, 30, 35 and 40 DAH, respectively,

irrespective of genotypes. At 45 DAH the germination recorded was 72

per cent which is above the MSCS. The MH sprayed @ 1250 ppm

recorded the mean germination of 27, 50, 53, 55, 64 and 69 per cent at 0,

5, 10, 15, 20, 25 and 25 DAH, respectively, irrespective of genotypes. At

30 DAH the germination recorded was 73 per cent which is above the

MSCS.

4.1.2 Effect of genotype

The data on effect of genotype on germination percentage of

bunchy groundnut after harvest as influenced by different concentrations

of MH are presented in Table 1 and Fig. 3.

From the data, it is seen that genotypes differed significantly in

respect of germination percentage during all the periods of testing. At 0

DAH, the genotype TG-26 recorded significantly the least mean

germination (34 %) followed by TAG-24 (39 %) and SB-XI (41 %),

irrespective of concentrations. At 5 DAH, the genotype SB-XI recorded

least mean germination (43 %) followed by TG-26 (49 %) and TAG-24

(81 %). The genotype SB-XI recorded significantly the least mean

germination of 45, 52, 56, 61 and 67 per cent at 10, 15, 20, 25 and 30

DAH, respectively, irrespective of concentrations. At 35 DAH the

30

germination was 72 per cent, which is above the MSCS. The genotype

TG-26 recorded the mean germination of 49, 52, 56, 60, 67 and 69 per

cent at 5, 10, 15, 20, 25 and 30 DAH, respectively, irrespective of

concentrations. At 35 DAH the germination was 74 per cent, which is

above the MSCS. The germination of the genotype TAG-24 recorded the

germination of above the MSCS during all the periods of testing, except

at 0 DAH (39 %), irrespective of concentrations.

4.1.3 Effect of interaction

The data on effect of interaction of genotype and concentration of

MH on induction of dormancy are presented in Table 1a.

From the data, it is seen that, the germination percentage of

varieties viz., TG-26, TAG-24 and SB-XI were significantly influenced

by the interaction effect between genotypes and concentrations of MH

during all the periods of testing (0 to 65 DAH).

4.1.3.1 Spray of water (control)

The variety TG-26 sprayed with water (control) recorded the mean

germination of 79, 94, 92, 92, 93, 93, 94, 94, 93, 93, 95, 95, 96 and 96 per

cent at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65 DAH,

respectively. The variety TAG-24 sprayed with water (control) recorded

the germination of 85, 92, 95, 95, 95, 94, 93, 94, 94, 96, 94, 94, 97 and 95

per cent at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65 DAH,

respectively. The variety SB-XI sprayed with water (control) recorded

the germination of 80, 92, 93, 91, 91, 92, 92, 90, 91, 95, 93, 96, 96 and 96

per cent at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65 DAH,

respectively.

31

4.1.3.2 MH @ 250 ppm and genotypes

The genotype TG-26 sprayed with MH @ 250 ppm recorded the

germination of 35, 51, 57 and 57 per cent at 0, 5, 10 and 15 DAH,

respectively. At 20 DAH the germination recorded was 70 per cent. The

genotype TAG-24 sprayed with MH @ 250 ppm recorded the

germination of 49 per cent at 0 DAH. At 5 DAH the germination

recorded was 91 per cent. The genotype SB-XI sprayed with MH @ 250

ppm recorded the germination of 41, 41, 44, 54, 56 and 61 per cent at 0,

5, 10, 15, 20 and 25 DAH, respectively. At 30 DAH, the germination

recorded was 71 per cent.


The genotype TG-26 sprayed with MH @ 500 ppm, recorded the

germination of 30, 42, 45, 51, 58, 66, 67 and 69 per cent at 0, 5, 10, 15,

20, 25, 30 and 35 DAH, respectively. At 40 DAH, the germination

recorded was 77 per cent. The genotype TAG-24 sprayed with MH @

500 ppm recorded the germination of 41 per cent at 0 DAH. At 5 DAH

the germination recorded was 84 per cent. The genotype SB-XI sprayed

with MH @ 500 ppm recorded the germination of 30, 35, 40, 47, 53, 56,

68 and 68 per cent at 0, 5, 10, 15, 20, 25, 30 and 35 DAH, respectively.

At 40 DAH the germination recorded was 77 per cent.




20, 25, 30 and 35 DAH, respectively. AT 40 DAH the germination



32







germination of 12, 27, 33, 39, 43, 54, 55, 61, 66 and 68 per cent at 0, 5,

10, 15, 20, 25, 30, 35, 40 and 45 DAH, respectively. At 50 DAH the

germination recorded was 80 per cent. The genotype TAG-24, sprayed

with MH @ 1000 ppm recorded the germination of 14 and 65 per cent at

0 and 5 DAH, respectively. At 10 DAH, the germination recorded was

81 per cent. The genotype SB-XI sprayed with MH @ 1000 ppm

recorded the germination of 14, 24, 29, 37, 40, 46, 52, 55, 56 and 59 per

cent at 0, 5, 10, 15, 20, 25, 30, 35, 40 and 45 DAH, respectively. At 50

DAH the germination recorded was 81 per cent.




20, 25, 30 and 35 DAH, respectively. At 40 DAH the germination







33

4.2 Seedling vigour index I

4.2.1 Effect of maleic hydrazide concentrations

The data on effect of concentrations of MH on seedling vigour

index (SVI) are presented in Table 2.

From the data, it is seen that the seedling vigour index differed

significantly due to spraying of various concentrations of maleic

hydrazide. The highest (2561, 2749, 2746, 2824, 2821, 2802, 2866,

2915, 2998, 3007, 3001, 3053 and 3060) SVI-I during all periods of

testing (0 to 65 DAH) was recorded in control seed sample i.e. without

MH spraying (water) irrespective of genotypes followed by the MH

sprayed @ 250 ppm, 500 ppm, 1250 ppm and 750 ppm during all the

periods of testing (0 to 65 DAH). While the MH sprayed @ 1000 ppm

recorded significantly the lowest (367, 1061, 1308, 1401, 1530, 1717,

1854, 2228, 2288, 2517, 2557, 2608, 2736 and 2787) SVI-I during all the

periods of testing (0 to 65 DAH).

4.2.2 Effect of genotypes

The data on effect of genotype on seedling vigour index of bunchy

groundnut after harvest as influenced by different concentrations of MH

are presented in Table 2.


respect of seedling vigour index I. The genotype TAG-24 recorded

significantly the highest (1166, 2248, 2543, 2545, 2623, 2645, 2685,

2761, 2795, 2832, 2856, 2863, 2946 and 2960) vigour index followed by

the genotype TG-26 (1116, 1347, 1363, 1589, 1690, 1876, 1911, 2289,

2384, 2695, 2723, 2795, 2884 and 2910). The genotype SB-XI recorded

the lowest (1007, 1245, 1287, 1503, 1593, 1789, 1840, 2204, 2290, 2590,

2652, 2712, 2810 and 2808) seedling vigour index during all the periods

of testing (0 to 65 DAH), irrespective of concentrations.

34



MH on SVI-I are presented in Table 2a.

From the data, it is seen that the interaction effect between

groundnut genotypes and concentrations of MH on SVI-I was significant

during all the periods of testing (0 to 65 DAH). The genotype TG-26

sprayed with water (control) recorded significantly the highest (2591,

2691, 2755, 2758, 2830, 2848, 2878, 2878, 2924, 2939, 2953, 2997,

3017, 3059 and 3075) SVI-I followed by the MH sprayed @ 250 ppm,

500 ppm, 120 ppm and 750 ppm during all the periods of testing (0 to 65

DAH), while the MH sprayed @ 1000 ppm recorded significantly the

lowest (380, 785, 839, 1086, 1115, 1413, 1422, 2032, 2153, 2504, 2524,

2584, 2824 and 2830) SVI-I. The genotype TAG-24 sprayed with water

(control) recorded highest (2348, 2768, 2885, 2924, 2973, 2940, 2961,

2971, 3037, 3103, 3172, 3188, 3222 and 3155) SVI-I, followed by the

MH sprayed @ 250 ppm, 500 ppm, 1250 ppm and 750 ppm during all the

periods of testing (0 to 65 DAH). While the MH sprayed @ 1000 ppm

recorded the lowest (379, 1690, 2138, 2163, 2393, 2485, 2500, 2580,

2670, 2690, 2698, 2718, 2841 and 2852) SVI-I. The genotype SB-XI

sprayed with water (control) significantly recorded the highest (2630,

2694, 2735, 2750, 2757, 2783, 2810, 2821, 2890, 2908, 2925, 2930, 2938

and 2970) SVI-I followed by MH sprayed @ 250 ppm, 500 ppm, 1250

ppm and 750 ppm during all the periods of testing (0 to 65 DAH), while

the MH sprayed @ 1000 ppm recorded significantly the lowest (343, 900,

945, 1060, 1210, 1430, 1518, 1530, 2237, 2351, 2416, 2559, 2740 and

2780) SVI-I during all the periods of testing (0 to 65 DAH).

35

4.3 Seedling Vigour Index - II


The data on effect of concentrations of MH on seedling vigour

index (SVI-II) are presented in Table 3.

From the data, it is seen that the seedling vigour index II differed

significantly due to spraying of various concentrations of maleic

hydrazide. The highest (483, 484, 486, 491, 503, 508, 514, 516, 520,

524, 530, 530, 535 and 540) SVI-II was recorded in control seed sample

i.e. spraying with water in all three genotypes during all periods of testing

(0 to 65 DAH), followed by the MH sprayed @ 250 ppm, 500 ppm, 1250

ppm and 750 ppm. The MH sprayed @ 1000 ppm recorded significantly

the lowest (36, 110, 122, 205, 230, 251, 279, 295, 320, 332, 364, 385,

395 and 399) SVI-II during all the periods of testing (0 to 65 DAH),

irrespective of genotypes.


The data on effect of genotype on seedling vigour index – II of

bunchy groundnut after harvest as influenced by different concentrations

of MH are presented in Table 3.


respect of SVI-II. The genotype TAG-24 recorded significantly the

highest (172, 281, 301, 414, 431, 433, 442, 468, 474, 479, 483, 489, 492

and 497) seedling vigour index II followed by the genotype TG-26 (132,

149, 165, 242, 250, 282, 296, 311, 348, 366, 416, 417, 423 and 433). The

genotype SB-XI recorded significantly the lowest (118, 124, 146, 224,

260, 289, 301, 310, 317, 344, 369, 379 and 379) seedling vigour index II

during all the periods of testing (0 to 65 DAH), irrespective of

concentrations.

36


The data on effect of interaction between genotypes and

concentrations of MH on SVI-II are presented in Table 3a.


groundnut genotypes and concentrations of MH on SVI-II were

significant during all the periods of testing (0 to 65 DAH). The genotype

TG-26 sprayed with water (control) recorded significantly the highest

(473, 480, 481, 486, 486, 501, 506, 516, 518, 520, 521, 534 and 543)

SVI-II, followed by the MH sprayed @ 250 ppm, 500 ppm, 1250 ppm

and 750 ppm during all the periods of testing (0 to 65 DAH), while the

MH sprayed @ 1000 ppm recorded significantly the lowest (23, 68, 78,

161, 167, 200, 211, 222, 287, 304, 374, 376, 459 and 466) SVI-II during

all the periods of testing (0 to 65 DAH). The genotype TAG-24 sprayed

with water (control) recorded significantly the highest (508, 514, 516,

522, 524, 526, 527, 528, 534, 535, 538, 546, 548 and 557) SVI-II

followed by the MH sprayed @ 250 ppm, 500 ppm, 1250 ppm and 750

ppm during all the periods of testing (0 to 65 DAH), while the MH

sprayed @ 1000 ppm recorded significantly the lowest (61, 219, 224,

319, 384, 385, 400, 418, 425, 425, 430, 472, 476 and 476) SVI-II during

all the periods of testing (0 to 65 DAH). The genotype SB-XI sprayed

with water recorded significantly the highest (394, 455, 462, 474, 484,

484, 490, 491, 493, 494, 496, 496, 503 and 510) SVI-II, followed by the

MH sprayed @ 250 ppm, 500 ppm, 1250 ppm and 750 ppm during all the

periods of testing. The MH sprayed @ 1000 ppm recorded significantly

the lowest (25, 42, 65, 134, 138, 159, 226, 244, 247, 263, 284, 323, 343

and 347) SVI-II during all the periods of testing (0 to 65 DAH).

37

4.4 Seedling dry weight (g)


The data on effect of concentrations of MH on SDW of genotypes


From the data, it is seen that seedling dry weight of genotypes

differed significantly due to spraying of MH at various concentrations.

The highest (3.9, 4.5, 5.1, 5.2, 5.2, 5.2, 5.3, 5.3, 5.4, 5.4, 5.4, 5.4, 5.5 and

5.6 g) SDW during all periods of testing (0 to 65 DAH) was recorded in

control seed sample i.e. water spraying irrespective of genotypes, while

the MH sprayed @ 1000 ppm recorded significantly the lowest (2.5, 2.5,

2.8, 3.7, 3.7, 3.9, 4.0, 4.0, 4.1, 4.1, 4.1, 4.1, 4.2 and 4.3 g) SDW,

irrespective of genotypes as compared to other concentrations i.e. MH

sprayed @ 250 ppm, 500 ppm, 750 ppm and 1250 ppm, during all the



The data on effect of genotypes on seedling dry weight of bunchy



From the data, it is seen that seedling dry weight of all the

genotypes differed significantly due to spraying of MH irrespective of

concentrations. The genotype TAG-24 recorded significantly the highest

(4.0, 4.1, 4.3, 4.4, 4.6, 4.6, 4.7, 4.8, 4.8, 4.9, 4.9, 4.9, 4.9 and 5.0 g) SDW

followed by TG-26 (2.6, 2.8, 3.6, 4.1, 4.1, 4.3, 4.5, 4.6, 4.6, 4.6, 4.6, 4.7,

4.7 and 4.8 g), while the genotype SB-XI recorded significantly the

lowest (1.9, 2.3, 3.0, 3.4, 3.7, 4.0, 4.0, 4.0, 4.2, 4.3, 4.3, 4.3, 4.3 and 4.5

g) SDW, irrespective of concentration during all the periods of testing (0

to 65 DAH).

38



MH on SDW of genotypes are presented in Table 4a.


groundnut genotypes and concentrations of MH on SDW of genotypes

were significant during all the periods of testing (0 to 65 DAH). The

genotype TG-26 sprayed with water recorded significantly the highest

(3.8, 4.5, 5.2, 5.4, 5.4, 5.4, 5.4, 5.5, 5.5, 5.5, 5.5, 5.6, 5.6 and 5.7 g) SDW,

while the MH sprayed @ 1000 ppm recorded the lowest (2.1, 2.2, 2.3,

3.3, 3.8, 3.9, 3.9, 4.0, 4.0, 4.1, 4.1, 4.1, 4.2 and 4.3 g) SDW, as compared

to other concentrations i.e. MH sprayed @ 250 ppm, 500 ppm, 750 ppm

and 1250 ppm during all the periods of testing (0 to 65 DAH). The

genotype TAG-24 sprayed with water recorded significantly the highest

(4.7, 4.8, 5.6, 5.7, 5.7, 5.7, 5.8, 5.8, 5.8, 5.9, 5.9, 5.9, 6.0 and 6.0 g) SDW,

while the MH sprayed @ 1000 ppm recorded significantly the lowest

(3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.2, 4.3, 4.4, 4.4, 4.5, 4.5, 4.5 and 4.6 g) SDW

as compared to other treatments i.e. the MH sprayed @ 250 ppm, 500

ppm, 750 ppm and 1250 ppm during all the periods of testing (0 to 65

DAH). The genotype SB-XI sprayed with water (control) recorded

significantly the highest (3.2, 4.2, 4.3, 4.6, 4.7, 4.8, 4.8, 4.8, 4.9, 4.9, 4.9,

5.0, 5.0 and 5.1 g) SDW, while the MH sprayed @ 1000 ppm

significantly recorded the lowest (1.4, 1.9, 2.1, 3.0, 3.3, 3.5, 3.6, 3.6, 3.8,

3.8, 3.9, 4.0, 4.1 and 4.2 g) SDW as compared to other concentrations i.e.

the MH sprayed @ 250 ppm, 500 ppm, 750 ppm and 1250 ppm during all

the periods of testing (0 to 65 DAH).

39

4.5 Moisture content (%)


The data on effect of concentration of MH on moisture content as

influenced by foliar spray of MH with various concentrations are

presented in Table 5.

From the data, it is seen that there was no significant difference in

moisture content of bunchy groundnut due to the various concentrations

of MH sprayed. However, numerically higher moisture content due to

water spray (32, 30, 29, 27, 25, 21, 18, 16, 11, 10, 9, 7, 7 and 7 per cent)

was recorded at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65

DAH, respectively, irrespective of genotypes as compared to various

concentrations of MH sprayed.


The data on effect of genotypes on moisture content of bunchy

groundnut as influenced by foliar spray of MH with various

concentrations are presented in Table 5.


respect of moisture content due to spraying of MH irrespective of


moisture content (33, 32, 29, 27, 24, 23, 19, 17, 12, 11, 9, 7, 7 and 7 per

cent) followed by the genotype TG-26 (32, 31, 29, 24, 22, 21, 17, 14, 10,

10, 9, 7, 7 and 7 per cent). The genotype SB-XI recorded significantly

the lowest moisture content (30, 29, 27, 24, 22, 20, 17, 14, 10, 10, 9, 7, 7

and 7 per cent) at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65

DAH, respectively irrespective of concentrations.

40

4.5.3 Interaction effect


concentrations of MH on moisture content of groundnut seeds are

presented in Table 5a.


moisture content of groundnut seeds due to the interaction between

groundnut genotypes and various concentrations of MH sprayed.

However, numerically higher moisture content was recorded due to

interaction between the genotypes TAG-24 sprayed with water (control)

(33, 33, 30, 27, 23, 23, 20, 18, 12, 11, 10, 8, 8 and 7 per cent) at 0, 5, 10,

15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65 DAH as compared to other

genotypes and various concentrations of MH sprayed.

4.6 Electrical conductivity (mmhos/cm)


The data on effect of concentrations of MH on EC of bunchy

groundnut seeds are presented in Table 6.

From the data, it is seen that significantly the highest EC (0.468,

0.448, 0.445, 0.440, 0.428, 0.416, 0.393, 0.361, 0.320, 0.317, 0.298,

0.286, 0.258 and 0.244 mm hos/cm) was recorded due to MH sprayed @

1000 ppm in comparison to MH sprayed @ 250 ppm, 500 ppm, 750 ppm

and 1250 ppm, while the lowest EC (0.409, 0.406, 0.402, 0.393, 0.386,

0.380, 0.349, 0.328, 0.290, 0.280, 0.272, 0.263, 0.231 and 0.224 mm

hos/cm) was recorded due to water spray (control) at 0, 5, 10, 15, 20, 25,

30, 35, 40, 45, 50, 55, 60 and 65 DAH, respectively, irrespective of

genotypes.

41


The data on effect of genotype on electrical conductivity of bunchy

groundnut after harvest are presented in Table 6.

From the data, it is seen that the genotypes differed significantly in

respect of electrical conductivity due to spraying of MH. The genotype

SB-XI recorded significantly the highest EC (0.448, 0.437, 0.426, 0.421,

0.411, 0.403, 0.370, 0.339, 0.300, 0.292, 0.282, 0.277, 0.243 and 0.236

mm hos/cm) followed by the genotype TG-26 (0.423, 0.420, 0.408,

0.403, 0.397, 0.390, 0.367, 0.340, 0.306, 0.297, 0.291, 0.271, 0.241 and

0.233 mm hos/cm). The genotype TAG-24 recorded significantly the

lowest EC (0.418, 0.408, 0.407, 0.401, 0.395, 0.387, 0.362, 0.342, 0.294,

0.287, 0.278, 0.267, 0.235 and 0.228 mm hos/cm) at 0, 5, 10, 15, 20, 25,

30, 35, 40, 45, 50, 55, 60 and 65 DAH, respectively, irrespective of




concentrations of MH on EC of bunchy groundnut seed are presented in

Table 6a.


groundnut genotypes and concentrations of MH were significant on EC of

bunchy groundnut seeds during all the periods of testing (0 to 65 DAH).

The genotype TAG-24 sprayed with MH @ 1000 ppm recorded the

highest EC (0.466, 0.459, 0.457, 0.443, 0.438, 0.416, 0.397, 0.368, 0.320,

0.323, 0.298, 0.289, 0.264 and 0.251 mm hos/cm) in comparison to MH

sprayed @ 250 ppm, 500 ppm, 750 ppm and 1250 ppm, while the control

42

recorded the lowest EC (0.404, 0.396, 0.397, 0.388, 0.386, 0.374, 0.342,

0.328, 0.279, 0.270, 0.263, 0.257, 0.232 and 0.225 mm hos/cm) during all

the periods of testing (0 to 65 DAH). The genotype TG-26 sprayed with

MH @ 1000 ppm recorded the highest EC (0.433, 0.442, 0.440, 0.428,

0.423, 0.415, 0.394, 0.355, 0.320, 0.310, 0.298, 0.288, 0.256 and 0.240

mm hos/cm) in comparison to MH sprayed @ 250 ppm, 500 ppm, 750

ppm and 1250 ppm, while the control recorded the lowest EC (0.404,

0.400, 0.400, 0.394, 0.386, 0.378, 0.353, 0.323, 0.290, 0.283, 0.280,

0.271, 0.234 and 0.227 mm hos/cm) during all the periods of testing. The

genotype SB-XI sprayed with MH @ 1000 ppm recorded significantly

the highest EC (0.464, 0.458, 0.457, 0.442, 0.427, 0.415, 0.397, 0.361,

0.313, 0.317, 0.298, 0.280, 0.255 and 0.242 mm hos/cm) in comparison

to MH sprayed @ 250 ppm, 500 ppm, 750 ppm and 1250 ppm, while the

control recorded significantly the lowest EC (0.417, 0.412, 0.403, 0.401,

0.386, 0.388, 0.352, 0.333, 0.290, 0.282, 0.275, 0.260, 0.226 and 0.219

mm hos/cm) during all the periods of testing (0 to 65 DAH).

4.7 Seed mycoflora (%)


The data on effect of concentrations of MH on per cent seed

mycoflora of bunchy groundnut genotypes are presented in Table 7.


seed mycoflora per cent of groundnut seeds due to the various

concentrations of MH sprayed ,during all the periods of testing (0 to 65

DAH).

43


The data on effect of genotypes on seed mycoflora of bunchy



respect of seed mycoflora irrespective of MH concentrations. The

genotype TG-26 recorded significantly the highest seed mycoflora (11,

13, 13, 14, 15, 15, 16, 18, 19, 20, 22, 25, 27 and 32 %) followed by the

genotype TAG-24 (6, 9, 9, 10, 11, 11, 12, 12, 14, 14, 15, 17, 18 and 26

%). The genotype SB-XI significantly recorded the lowest seed

mycoflora (7, 7, 7, 7, 8, 8, 8, 10, 10, 12, 12, 14, 15 and 23 %) at 0, 5, 10,

15, 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65 DAH, respectively,

irrespective of concentrations. However, the important predominant

pathogens recorded were Aspergillus flavus, Aspergillus niger, Fusarium

moniliforme, Rhizophus spp. and Penicillium spp.



concentrations of MH on per cent seed mycoflora are presented in

Table 7a.


per cent seed mycoflora of bunchy groundnut due to the interaction

between groundnut genotypes and various concentrations of MH sprayed,


44

4.8 100 kernel weight (g)


The data on effect of concentrations of MH on 100 kernel weight



100 kernel weight of bunchy groundnut due to the various concentrations

of MH. However, numerically higher 100 kernel weight was recorded

due to spraying of MH @ 1000 ppm during all the periods of testing.


The data on effect of genotypes on 100 kernel weight of bunchy

groundnut after harvest as influenced by foliar spray of MH at various

concentrations are presented in Table 8.


respect of 100 kernel weight due to spraying of MH irrespective of


100 kernel weight (51, 49, 48, 48, 48, 47, 46, 45, 45, 44, 44, 44, 43 and

43 g) followed by the genotype TG-26 (48, 45, 45, 44, 42, 42, 41, 41, 40,

40, 40, 40, 40 and 39 g) while the genotype SB-XI significantly recorded

the lowest 100 kernel weight (47, 44, 43, 42, 41, 40, 39, 39, 39, 38, 38,

37, 37 and 36 g) irrespective of concentrations of MH, during all the




concentrations of MH on 100 kernel weight of groundnut seeds are


45


100 kernel weight of groundnut seed due to the interaction between


However, numerically higher 100 kernel weight was recorded due to

interaction between the genotype TAG-24 sprayed with MH @ 1000 ppm


4.9 Shelling percentage


The data on effect of concentrations of MH on shelling percentage

of bunchy groundnut genotypes are presented in Table 9.


shelling percentage of groundnut genotypes due to the various

concentrations of MH sprayed. However, numerically higher shelling

(80.64 and 69.63 %) was recorded due to spraying of MH @1000ppm at

0 and 65 DAH, respectively, irrespective of genotypes.


The data on effect of genotypes on shelling percentage of bunchy



respect of shelling percentage irrespective of MH concentrations. The

genotype TAG-24 recorded significantly the highest shelling percentage

of 82.24 % and 70.55 % followed by the genotype TG-26 80.38 % and

69.31 %. The genotype SB-XI recorded significantly the lowest shelling

percentage of 78.76 % and 68.74 % at 0 and 65 DAH, respectively,

irrespective of concentrations.

46



concentrations of MH on shelling percentage are presented in Table 9a.

From the data, it is seen that there was no significant difference on

shelling percentage of bunchy groundnut due to the interaction between


However, numerically higher shelling per cent of 82.64 % and 70.90 %

was recorded due to the interaction between genotype TAG-24 and the

MH sprayed@1000ppm at 0 and 65 DAH, respectively in comparison to

other genotypes and concentrations of MH sprayed.

4.10 Oil content (%)

4.10.1Effect of maleic hydrazide concentrations

The data on effect of concentrations of MH on oil content of

bunchy groundnut seeds as influenced by foliar spray of MH are

presented in Table 9.


oil content of groundnut seed due to the various concentrations of MH

sprayed. However, numerically higher oil content of 43.96 and 48.12 per

cent was recorded due to spraying of MH @ 1000 ppm at 0 and 65 DAH,

respectively, irrespective of genotypes.

4.10.2Effect of genotypes

The data on effect of genotypes on oil content of bunchy groundnut

seed after harvest are presented in Table 9.

47


respect of oil content, irrespective of MH concentrations. The genotype

TAG-24 recorded significantly the highest oil content of 45.12 and 48.93

per cent followed by the genotype SB-XI as it was 44.00 and 47.33 per

cent at 0 and 65 DAH, respectively, irrespective of concentrations of MH

sprayed while the genotype TG-26 recorded significantly the lowest oil

content of 43.85 and 46.09 per cent.

4.10.3Effect of interaction


concentrations of MH on oil content are presented in Table 9a.


oil content of bunchy groundnut seeds due to the interaction between


However, numerically higher oil content of 45.47 and 49.23 per cent was

recorded due to the interaction between the genotype TAG-24 sprayed

and MH @ 1000 ppm as compared to other genotypes and concentrations

of MH sprayed, respectively at 0 and 65 DAH.

4.11 Protein content (%)


The data on effect of concentrations of MH on protein content of

bunchy groundnut seeds are presented in Table 9.


protein content of groundnut seed due to the various concentrations of

MH. However, numerically higher protein content of 24.87 and 24.98

48

per cent was recorded due to spraying of water at 0 and 65 DAH,

respectively, irrespective of genotypes.


The data on effect of genotype on protein content of bunchy




respect of protein content irrespective of MH concentrations. The

genotype TAG-24 recorded significantly the highest protein content of

25.36 and 25.58 per cent followed by the genotype TG-26 as it was 24.46

and 24.53 per cent at 0 and 65 DAH, respectively, irrespective of

concentrations of MH. While the genotype SB-XI recorded significantly

the lowest protein content of 23.87 and 24.08 per cent.

4.11.3Interaction effect


concentrations of MH on protein content are presented in Table 9a.


protein content of bunchy groundnut seeds due to the interaction between


However, numerically higher protein content of 26.03 and 25.66 per cent

was recorded due to the interaction between the genotype TAG-24

sprayed with water at 0 and 65 DAH, as compared to other genotypes and


49

4.12 Tetrazolium test


The data on effect of concentrations of MH on per cent viable

seeds are presented in Table 9.


groundnut seed viability as tested by TZ test due to the various

concentrations of MH. However, there was numerically higher (93.89 %)

seed viability was recorded due to spraying of MH @ 1000 ppm.


The data on effect of genotype on seed viability as tested by TZ

test of bunchy groundnut after harvest as influenced by different

concentrations of MH are presented in Table 9.

From the data, it is seen that genotypes shown non-significant

difference in respect of per cent viable seeds as tested by TZ test.

4.12.3Interaction effect


concentrations of MH on per cent viable seeds as tested by TZ test are



groundnut seed viability as tested by TZ test due to the interaction

between groundnut genotypes and various concentrations of MH sprayed.

However, numerically higher seed viability (94.67 %) was recorded due

to interaction between the genotype TG-26 sprayed with MH @ 1000

ppm as compared to other genotypes and concentrations of MH sprayed.

50

4.13 Sound mature kernel percentage (SMK %)


The data on effect of concentrations of MH on SMK percentage of

bunchy groundnut seeds are presented in Table 9.


SMK percentage of groundnut seeds due to the various concentrations of

MH sprayed. However, numerically higher SMK per cent of 92.09 %

was recorded due to spraying of MH @ 1000ppm at 65 DAH,

irrespective of genotypes.


The data on effect of genotype on sound mature kernel percentage

of bunchy groundnut seeds are presented in Table 9.

From the data, it is seen that the genotypes differed significantly in

sound mature kernel percent, irrespective of MH concentrations. The

genotype SB-XI recorded significantly the highest SMK per cent of 93.62

% followed by the genotype TG-26 as it was SMK per cent of 92.49 %.

The genotype TAG-24 recorded significantly the lowest SMK per cent of

91.05 % at 65 DAH, irrespective of concentrations.

4.13.3Effect of interaction


concentrations of MH on SMK percentage are presented in Table 9a.


SMK percentage of bunchy groundnut seeds due to the interaction

between groundnut genotypes and various concentrations of MH sprayed.

However, numerically higher of 94.03 % SMK was recorded due to the

interaction between genotype SB-XI and MH sprayed @ 1000 ppm at 65

DAH, as compared to other genotypes and the concentrations of MH

sprayed.

51

52

5. DISCUSSION

A field trial was conducted to study the induction of seed

dormancy in bunchy groundnut varieties viz., TG-26, TAG-24 and SB-XI

by various concentrations viz., 250, 500, 750, 1000 and 1250 ppm of MH

sprayed at 60 and 90 DAS alongwith control during the summer 2007.

The results obtained are discussed in this chapter.

5.1 Induction of dormancy due to MH spray

In current investigation, the comparison between different

genotypes in respect of per cent germination when sprayed with various

concentrations of MH at 60 and 90 DAS revealed that the genotypes

differed significantly, at 0 to 65 DAH. The genotype SB-XI recorded the

lowest (41, 43, 45, 52, 56, 61, 68, 71, 75, 77, 88, 89, 92 and 92 %)

germination during all the periods of testing than the genotype TG-26,

while the genotype TAG-24 recorded the highest (39, 81, 91, 91, 91, 92,

92, 93, 90, 92, 91, 91, 92 and 93 %) germination during all the periods of

testing. Among the three genotypes SB-XI and TG-26 responded well for

induction of dormancy by MH spray, as the dormancy was induced upto

30 days in these genotypes, irrespective of concentrations. While the

genotype TAG-24 didn’t respond well for dormancy induction by MH

spray, as the dormancy induced was only for 5 days. After 5 days

dormancy was broken down, as the germination recorded after 5 days was

above the MSCS. Among the foliar application of MH at different

concentrations reduced the subsequent germination of seeds due to

induction of dormancy as compared to control (water spray). Spraying of

MH @ 1000 ppm concentration was most effective in inducing dormancy

53

as the germination recorded (13, 39, 47, 48, 57, 64, 65, 69, 69, 72, 83, 86,

88 and 89 %) to a greater extent, it might be due to lethal inhibitory effect

of MH. All the genotypes had non-dormant nature it could be seen from

the control sample (water spray) and recorded the highest (82, 93, 92, 93,

91, 93, 92, 92, 92, 95, 94, 94, 95 and 94 %) germination percentage,

followed by the MH sprayed @ 250, 500, 1250 and 750 ppm

concentrations during all the periods of testing. The genotype SB-XI

sprayed with MH @ 1000 ppm, had given the minimum (14, 24, 29, 37,

40, 46, 52, 55, 56, 59, 81, 85, 88 and 91 %) germination percentage

during all the periods of testing than the genotype TG-26 and TAG-24

stating that maximum dormancy was induced in SB-XI @ 1000 ppm

concentration of maleic hydrazide. The MH application on lower

concentration at 60 and 90 DAS of crop growth failed to induce

dormancy, as the lower concentration might have limited penetration and

translocation of the chemical to the growing meristem.

Dormancy may block any of the sequential processes involved in

the germinations. The work of earlier scientists revealed that the

application of an inhibitor (MH) could bring about certain changes in the

physiological and biochemical processes like alteration in promoter to

inhibitor ratio, moisture content of the seed, water absorption capacity of

the seeds, protein content and oil content of the seed, which are

responsible to make the seed dormant by way of arresting the growth of

the embryo. Another important conception was that, dormant and non-

dormant state of the seed was dependent on relative levels of inhibitors

and promoters present in the seed (Khan, 1977 and Bewley and Black,

1982). The non-dormant nature of bunch groundnut was due to increase

in the level of growth promoting auxin during the seed development and

maturity (Sreeramulu and Rao, 1971a).

54

The non-dormant nature of bunchy groundnut is due to the

presence of growth promoting water soluble auxin (Nagarjun and

Gopalkrishnan, 1958 and Ketring, 1977). Since, MH is an auxin-

antagonist, the primary effect of MH on inducing dormancy seems to be

through interference in the trypotophan metabolism, as the tryptophan is

the precursor in the synthesis of auxins (Karivaratharaju and Rao, 1972).

Besides this, MH is found to increase the content of another amino acid,

hydroxyproline (Karivaratharaju and Rao, 1972 and Vaithialingam and

Rao, 1973a); which inhibits the auxin induced cell elongation (Cleland,

1963).

The introduction of antiauxins to the seed by means of foliar

application at the time of kernel development may suppress the auxin

formation and induce dormancy (Leopold, 1958). Maleic hydrazide a

growth and respiratory inhibitor, possesses the characteristics of antiauxin

and has been found to be capable of inducing dormancy by antagonizing

with auxin in groundnut, potato, sugarbeet, carrot and rice by interfering

in root growth and water absorption (Ellison and Smith, 1948; Patterson

et al., 1952; Wittwar and Hansen, 1951; Krishnamurthy, 1967). Maleic

hydrazide application on onion plant prolongs its dormancy via its effects

on nucleic acid synthesis and cell division rather than a direct effect on

the level of natural growth inhibitor and promoters in the bulbs (Abdel-

Rahaman and Issenberg, 1974).

The results obtained in present investigation are in confirmation

with the results reported by Nautiyal (2004), who reported that MH

sprayed @ 1000 ppm concentration induced dormancy much better in

non-dormant groundnut varieties. Gupta et al. (1985) stated that effect of

MH in inducing dormancy in groundnut varieties was found to be

55

increased with increase in the concentration and reported MH sprayed @

20 x 103 ppm had induced more dormancy than 5 x 103, 10 x 103 and 15 x

103 ppm. Randhawa and Nandapuri (1986) reported that MH sprayed @

1000 ppm concentrations reduced the sprouting per cent in onion bulbs.

Nagarjun et al. (1980) and Abrar and Jadhav (1991) reported that 250

ppm and 200 ppm, respectively could induce dormancy in bunch

groundnut seeds for a period of 3-4 weeks.

Table 10. Dormancy (days) induced by different concentrations of

Maleic hydrazide in different varieties of groundnut

Genotypes

Concentrations

Number of days

TG-26 TAG-24 SB-XI Irrespective of genotypes

Control No dormancy No dormancy No dormancy No dormancy

250 ppm 15 5 25 15

500 ppm 35 5 35 20

750 ppm 35 5 35 25

1000 ppm 45 5 45 40

1250 ppm 35 5 35 25

Irrespective of concentrations

30 5 30 -

5.2 Seedling vigour index I, II and seedling dry weight (g)

The comparison between seedling vigour index I, II and SDW as

influenced by different treatments revealed that the genotypes differed

significantly in respect of seedling vigour I, II and SDW due to their

genetic make up and inhibitory effect of MH. The variety TAG-24

recorded significantly the highest seedling viour index I, II and seedling

dry weight followed by the genotype TG-26, irrespective of

concentrations of MH during all the periods of testing. The genotype SB-

56

XI recorded the least seedling vigour index I, II and seedling dry weight.

The control (water spray) recorded significantly the highest seedling

vigour index I, II and seedling dry weight, respectively, followed by MH

sprayed @ 250, 500, 1250 and 750 ppm, irrespective of genotypes. The

MH sprayed @ 1000 ppm concentration recorded significantly lowest

seedling vigour index I, II and seedling dry weight during all the periods

of testing. The variety SB-XI and the MH sprayed @ 1000 ppm

concentration had recorded the lowest seedling vigour index I, II and

seedling dry weight, followed by the genotype TG-26 and TAG-24. The

genotypes sprayed with water (control) had given the more seedling

vigour index I, II and SDW during all the periods of testing (0 to 65

DAH).

Among the various concentrations of maleic hydrazide, the MH @

1000 ppm worked effectively as growth retardant irrespective of

genotypes whereas among the genotypes, SB-XI responded well to MH

irrespective of its concentrations for reducing its vigour which might be

sign for induction of dormancy. The decline in seedling vigour index I

and II could be due to less germination as result of MH spray. The

reduction in seedling dry weight due to various concentrations of MH

sprayed, might be due to inhibitory effect of growth retardants on

seedling growth by affecting the shoot length, root length and often also

the stem elongation (Pandey and Sinha, 2006). The amount of growth

retardants decreases during the active growth period of plants and

increases during the period of growth suppression. Thus, reducing the

biomass resulting in low dry weight as compared to control. MH

application at all the concentrations reduced the dry matter content of

seedlings compared to control. These results are in accordance with

Nagarjun and Radder (1983a).

57

5.3 Moisture content (%)

The moisture content as influenced by different treatments revealed

that the genotypes differed significantly in respect of seed moisture

content. The genotype TAG-24 recorded significantly the highest

moisture content, followed by the genotype TG-26. The genotype SB-XI

recorded significantly the lowest moisture content during all the periods

of testing. The moisture content as influenced by various concentrations

of MH sprayed, showed non-significant difference on moisture content of

seed during all the periods of testing. The interaction effect was non-

significant.

However, Jagatap (2000), Nagarjun et al. (1980) and Nagarjun and

Rudder (1983) reported that reduction in moisture content due to MH

spray at various concentrations as compare to control.

5.4 Electrical conductivity (mmhos/cm)

The electrical conductivity as influenced by different treatments

revealed that, the genotypes differed significantly in respect of electrical

conductivity of groundnut seeds. The genotype SB-XI recorded the

highest EC, followed by the genotypes TG-26 and the genotype TAG-24

during all the periods of testing. The electrical conductivity as influenced

by the MH sprayed @ 1000 ppm and control (water spray) recorded the

highest and lowest EC, respectively, than other concentrations of MH

applied. All the three genotypes sprayed with MH @ 1000 ppm recorded

the highest EC while the control (water spray) recorded the lowest EC, as

compare to other concentrations of MH sprayed.

The seeds which give high EC have been found to be correlated

with low field emergence. Seeds with very high EC may not be suitable

58

for sowing (Agarwal, 1995). The highest EC might be due to inhibitory

effect of MH, as it was inhibited the germination of groundnut seeds in

the genotypes SB-XI and TG-26. It could be the reason that, these

varieties recorded the highest EC value. The genotype TAG-24 recorded

comparatively lower EC value, as it was recorded more germination

percentage. Among the various concentrations of MH sprayed the MH

sprayed @ 1000 ppm recorded higher EC, it could be attributed to

inhibition of germination of seeds. The seed from control recorded the

lowest EC as it gave more germination percentage.

5.5 Seed mycoflora (%)

The per cent seed mycoflora as influenced by different treatments

revealed that, the genotypes differed significantly in respect of per cent

seed mycoflora. The genotype TAG-24 recorded the highest per cent

seed mycoflora followed by the genotype TG-26 and the genotype SB-XI

during all the periods of testing. The per cent seed mycoflora as

influenced by various concentrations of MH sprayed, showed non-

significant difference during all the periods of testing. The freshly

harvested crop showed less per cent seed mycoflora at initial period of

testing which increased at later periods of testing. Observation taken on

per cent seed mycoflora was every 5 days interval upto two months from

the date of harvesting. The important pre-dominant seed pathogens

noticed during the periods of testing were Aspergillus flavus, Aspergillus

niger, Fusarium moniliforme, Rhizophus spp. and Penicillium spp. The

present results obtained are in conformity with the work of Javeed et al.

(1998), Rasheed et al. (2004) and El-Magharaby et al. (2007) who

reported the same seed pathogens in their experiment, who analysed the

seed samples after every month upto one year.

59

5.6 100 kernel weight (g), Shelling percentage and Sound mature

kernel (%)

The 100 kernel weight as influenced by different treatments

revealed that, the genotypes differed significantly in respect of 100 kernel

weight. The genotype TAG-24 recorded the highest 100 kernel weight

followed by the genotypes TG-26 and SB-XI during all the periods of

testing (0 to 65 DAH). It might be due to their genetic makeup. There

was no significant difference in 100 kernel weight as influenced by

various concentrations of MH sprayed. Non-significant effect on 100

kernel weight could be attributed to unaffected yield contributing

characters due to MH spray. The present results are in accordance with

the work of Gupta et al. (1985) who reported non-significant difference

on seed index (gm) due to MH spray at various concentrations.

The shelling percentage as influenced by different treatments

revealed that, the genotypes differed significantly in respect of shelling

percentage. The genotype TAG-24 recorded highest (82.24 and 70.55 %)

shelling percentage followed by the genotype TG-26 (80.38 and 69.39 %)

and the SB-XI (78.76 and 68.74 %) at 0 and 65 DAH, respectively. At 0

DAH all three genotypes recorded more shelling percentage due to more

moisture content. At 65 DAH, shelling percentage was reduced due to

reduction in moisture content. The difference in shelling percentage

among the genotypes is due to their genetic makeup. The shelling

percentage as influenced by various concentrations of MH sprayed was

non-significant. Non-significant effect on shelling percentage might be

due to unaffected yield contributing characters due to MH spray. The

present results obtained are not in accordance with the results reported by

60

Gupta et al. (1985) who observed reduction in shelling percentage due to

MH spray.

The sound mature kernel percentage as influenced by different

treatments revealed that, the genotypes differed significantly in respect of

sound mature kernel percentage. The genotype SB-XI recorded highest

(93.62 %) SMK percentage, followed by the genotype TG-26 (92.49 %)

and TAG-24 (91.05 %) at 65 DAH. Though the genotype SB-XI

recorded lowest shelling percentage but it recorded highest sound mature

kernel percentage. The genotype TAG-24 recorded highest shelling

percentage, but it recorded lowest sound mature kernel percentage. It

could be attributed more number of uniform and fully matured seeds in

genotype SB-XI. It can also be correlate with highest induction of

dormancy, due to spraying of MH, which might have reduced the

vegetative growth and diverted all the food material towards sink i.e.

pods. The present results are in conformity with the work of Nagarjun et

al. (1980) who studied purity of seed (per cent uniform sized and matured

seed) and reported that change in the concentration of MH application did

not show any significant adverse or beneficial effect on the seed purity.

5.7 Oil and Protein content (%)

The oil content as influenced by different treatments revealed that,

the genotypes differed significantly in respect of oil content. The

genotype TAG-24 recorded the highest (45.12 and 48.93 %) oil content,

followed by the genotype SB-XI (44.00 and 47.73 %) and TG-26 (43.35

and 46.09 %) at 0 and 65 DAH, respectively. The difference in oil

content among the genotypes might be due to their genetic makeup. The

slight increase in the oil content due to MH spray, might be due to the

61

greater availability and translocation of mineral elements, especially

sulphur which was directly involved in biosynthesis of oil (Nagarjun and

Rudder, 1983 and Suryanarayana et al., 1976) who also found increased

oil content due to the foliar spray of MH.

The protein content as influenced by different treatments revealed

that, the genotypes differed significantly in respect of protein content.

The genotype TAG-24 recorded significantly the highest (25.36 and

25.58 %) protein content, followed by the genotype TG-26 (24.46 and

24.53 %) and SB-XI (23.87 and 24.08 %) at 0 and 65 DAH, respectively.

The difference in protein content among the genotypes might be due to

their genetic make up. There was slight reduction in the protein content

due to MH application at different concentrations.

The present results obtained are in accordance with the work of

Nagarjun and Rudder (1983a) who also did not find greater reduction in

protein content in Spanish improved peanut due to foliar spray of MH and

Paterson et al. (1952) who did not observe any change in the nitrogen

content of potato tubers due to foliar spray of MH to the crop, as there is

no degradation of protein with the MH application. However,

Karivartharaju and Rao (1972) reported increase in protein content.

5.8 Tetrazolium test (TZ test) (%)

The seed viability as tested by TZ test as influenced by different

treatments revealed that, the viability of different genotypes and

concentrations as tested by TZ test had shown non-significant difference.

The present results of the study indicated that the viability of seed

from foliar spray of MH at concentrations ranging from 250 ppm to 1250

ppm successfully induced the dormancy in the genotypes which is shown

62

by viability test indicating that, there was a viability, however

germination was inhibited due to MH spray. Hence, it can be stated that

the MH is safe to induce dormancy in groundnut.

Maleic hydrazide known to act as respiration inhibitor (Paterson et

al., 1952). Loss of viability occurs due to an irreversible physiological

and biochemical changes in seed (Narasimha Reddy and Swamy, 1977).

Viability of a seed is lost due to inactivation of enzymes, proteins and

loss of reserved food material due to respiration (Pandey and Sinha,

2006). In this context maleic hydrazide inhibits respiration and arrests

loss of reserved food and inactivation of proteins and enzymes. Hence

maleic hydrazide does not cause a detrimental effect, as there was no loss

of seed viability. The present results are in conformity with the

(Nagarjun et al., 1980) reported that the change in the concentration of

MH application did not show any significant adverse effect on the seed

viability as tested by TZ test.

63

6. SUMMARY AND CONCLUSIONS

A field experiment was conducted to study the induction of seed

dormancy as influenced by various concentrations of MH in bunchy type

groundnut (Arachis hypogaea) genotypes at Seed Technology Research

Unit (STRU) farm, MPKV, Rahuri. Three genotypes viz., TG-26, TAG-

24 and SB-XI were used. The MH sprayed with various concentrations

viz., 250 ppm, 500 ppm, 750 ppm, 1000 ppm and 1250 ppm alongwith

control at 60 and 90 DAS. The various observations like germination

(%), seedling vigour index I and II, seedling dry weight (g), moisture

content (%), electrical conductivity (mmhos/cm), seed mycoflora (%) and

100 kernel weight (g) were recorded at every 5 days interval, starting

immediately after harvest, while shelling percentage, oil content (%),

protein content (%) were recorded at 0 and 65 DAH and seed viability

(TZ test %) and sound mature kernel (%) were recorded at 0 and 65

DAH, respectively.

The following conclusions are drawn from this study.

1. The spraying of MH at 60 and 90 days after sowing could

induced dormancy upto 30 days in the genotypes SB-XI and

TG-26 whereas only 5 days of dormancy could be induced in

the genotype TAG-24, irrespective of concentrations.

2. The MH sprayed @ 250 ppm, 500 ppm, 1250 ppm, 750 ppm

and 1000 ppm could induced dormancy of 15, 20, 25, 25 and

40 days, respectively, irrespective of genotypes.

3. The spraying of Maleic hydrazide @ 1000 ppm reduced the

seedling vigour index I and II, seedling dry weight, electrical

conductivity and seed moisture content as compared to

64

control and other concentrations viz., 250, 500, 750 and 1250

ppm applied which shows the effectiveness of MH @ 1000

ppm for induction of dormancy.

4. The seed quality parameters viz., seed viability (%), 100

kernel weight (g), shelling percentage, sound mature kernel

(%), per cent seed mycoflora, oil content (%) and protein

content (%) remain unaffected in all the varieties due to

spraying of maleic hydrazide.

It is concluded that foliar application of Maleic hydrazide @

1000 ppm at 60 and 90 days after sowing could induce seed

dormancy upto 45 days in the genotypes SB-XI and TG-26

whereas, only 5 days dormancy could induce in the variety

TAG-24.

Table 10. Dormancy (days) induced by different concentrations of

Maleic hydrazide in different varieties of groundnut

Genotypes

Concentrations

Number of days

TG-26 TAG-24 SB-XI Irrespective of genotypes

Control No dormancy No dormancy No dormancy No dormancy

250 ppm 15 5 25 15

500 ppm 35 5 35 20

750 ppm 35 5 35 25

1000 ppm 45 5 45 40

1250 ppm 35 5 35 25

Irrespective of concentrations

30 5 30 -

65

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76

8. VITA

Mr. JAYADEVA B.

A candidate for the degree

of

MASTER OF SCIENCE (AGRICULTURE)

in

SEED SCIENCE AND TECHNOLOGY

Title of thesis : “Induction of seed dormancy in summer groundnut (Arachis hypogaea L.) ”

Major field : Seed Science and Technology

Biographical information :

Personal : Born at Megalahatti, Tal. Molakalmuru, Dist. Chitradurga (Karnataka) on 7th July, 1983. Son of Shri. Boranayaka P. and Smt. Obamma.

Educational : Passed S.S.L.C. examination from SNS High School, Hanagal, Dist. Chitradurga in 2000 and P.U.C. examination from ST Rural Composite PU College, Nayakanahatti, Dist. Chitradurga in 2002 with First Class.

Received Bachelor of Science (Agriculture) degree from College of Agriculture, Dharwad,UAS, Dharwad in 2006 with First Class.

Achievements : Awarded JRF for PG degree programme by ICAR, New Delhi.

Passed N.C.C. ‘B’ and ‘C’ certificates

Elected as Vice-President of Students’ Association, College of Agriculture, Dharwad during 2003-04.

Permanent Address

: At – Megalahatti, Tal. Molakalmuru, Dist. Chitradurga-577 535 (Karnataka)Phone No. (08198) 229019

77

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