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FLORAL BIOLOGY ANDFRUIT SET

OFMANGO,CITRUS AND

GRAPE

M.Vijayalaxmi

RHM/08-23

M.Sc(Hort)1st

yr

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BLOSSOM BIOLOGY

In many fruit crops the time of flower opening depends onthe many factors

Blossom biology constitutes

Blooming period Flower bud differentiation

Flower bud development

Inflorescence

Sex ratio

Anthesis Dehiscence

Pollen fertility

Stigma receptivity

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Mango

SN : Mangifera indica

Family : Anacardiaceae

Inflorescence : Panicle

Fruit : Drupe

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Blooming period

Factors

Physiological CHO and N reserves play a main role in fruit bud

differentiation. Environmental - optimum 20-25oC. vegetative shoots produced

in spring get sufficient time to grow and accumulate metabolites

necessary for fruit bud differentiation.

S I : January - February

N I : February March

2-3 weeks

Flower bud differentiation

October December

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Inflorescence:

the panicle consists of pefecthermophrodite and male flowers.

the percentage of perfect flowersranges from 1.25- 81.0% with astrong varietal difference.

800 9000 flowers / panicle

Male and Perfect flowers presenttowards apex

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Flower

6 8 mm in diameter

Calyx : 5 partite

Corolla : 5 (greenish yellow and

cream colour)

Androecium : 5 lobed disc

(stamens and staminoids)

Stamens and pistils may be either parallel or

oblique to each other

Ovary is sessile,one celled,oblique and slightly

compressed in its lateral aspects

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Sex ratio

Perfect to staminate

Less flowers in distal half

More perfect flowers in the distal half

1.25%Jahangir

3%Baneshan

6-11%Alphonso

16%Neelum

80%Dashehari

Percentage of perfect

flowers

Variety

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Factors affecting for more perfect flowers

Inflorescence emerging during middle and end of

flowering season (2-7 times)

Lateral inflorescence Older trees Grafted trees On year crop Ambient temperature

Mineral nutrition

Anthesis9.00AM - 10.00AM polyembryonic sps night

DehiscenceOccurs within 1 hr after anthesis after dehiscence anthers

become bluish due to pollen High RH delays dehiscence

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Pollination

Highly cross pollinated, perfect flowers are protogynous and

entemophilous

Pollen grains in mango changes shapes in different media

Possess oblong, oval and slightly broader in some varieties

3 types of pollinating agents

Melipona spp Syrphidae spp Musca domestica

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Pollen fertility

Growth and maturity reduced by cool

temperatures

Completely inhibits at below 15oc

Stigma receptivity

Up to 72 hours after opening of flower

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FRUIT SET

Development of ovary and theadjacent tissue following

blossom period

8-13% flowers setting Mango cv are usally self fruit ful

Ratio of fruit to flower is 1 :5000

fruits less than 1% reach maturity

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Factors for low fruit set

More male flowers

Un pollinated perfect flowers

Failure of pollen germination

Factors responsible for fruit set

Changes in temperature

Light intensity

Day length

Presence of functional leaves

Supply of nutrients and water

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Parthenocarpy

Not common but seen in Dashehari (5.44%)

due to low temperature during flowering andreduce the activity of pollinators

Fruit drop

Climatic conditions

Defective flowers

Self in compatibility

Lack of pollination

Zygote abortion

Pests and diseases

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Alternate bearingAlternate bearing refers to heavy fruiting In one year

Factors

5. Physiological

6. Genetical

7. Environmental8. Nutritional

Measures

Maintenance of orchard Deblossoming Ringing and girdling Smudging and chemical treatments

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Sn : Citrus spp.

Family : Rutaceae

Inflorescence : Terminal cyme

Fruit : Hesperidium

CITRUS

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Blooming period

March-april (early spring)

Sweet orange and mandrins - once in a year

(March) - NI

Sweet orange - First (Feb-Mar)

Second ( June-July ) - Bihar

Sathgudi - First (Dec-April) - SI

Second ( Sep-Dec)

Coorg mandrin - First (Mar-April)

Second ( Sep-Oct)

Thrice in central and western India June,Oct and Feb

Continuous bloom in Lemons, Lime and Citron

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Flowering in tropical regions

With no cool periods and enough soil moistures through out

the year, most of the citrus species produce some bloom on a

recurrent basis

Hence low temperature alone is not induced flowering but

dormancy induced by low moisture supply has been found

equally effective.

The flowering in citrus under Indian conditions is induced

through eitherlow temperature stress orsoil water deficit.

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In North-west India and North-East India low temperature isobserved for 10-15 days, which is sufficient to induce

dormancy.

In central and South India in the absence of low temperature,soil water deficit stress is adopted to induce flowering.

There are very few commercial citrus growing belts of global

level where soil water deficit is widely practiced to induce

flowering

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Flowering in tropical regions

Cessation of root growth, as well as low temperature,

water stress, weak root stocks and confined roots

were necessary for floral induction.

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Flower bud differentiation

Every vegetative bud in citrus is a potential flower

bud. Induction and differentiation are not seen outside

The vegetative bud in citrus is conical one withpointed apex

Cessation of vegetative growth is a pre-requisite for

induction

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It is generally observed that new flush precedes theflower bud differentiation, ordinarily in early spring

Temperature required is 16 -20o

c (Krajewski etal.,1995)

flower bud development Complete development ofbud lasts from less than 18 47 days (Inova,1990)

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Inflorescence

Inflorescence in citrus species is of cymose type.

Flowers in citrus are borne on two types of shoots

1. With leaves : new wood

2. With out leaves : old wood

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Flower

Calyx : 5 sepals, gamosepalous, inferior, quincunicial

aestivation

Corolla : 5 (white/purplish colour), polypetalous scented,

inferior, imbricate aestivation

Androecium : Indefinate, 20 - 40stamens, polydelphous,

compressed at base. Anthers oblong basifixes, introse, dithecous

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Gynoecium : Polycarpellary, syncarpous, superior

ovary, multi locular, nectar secreting, disc presentbelow ovary, axile placentation, style short, stigma

capitative7-15 celled pistils

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Flowering in Citrus:

In Israel, Eureka lemons sprayed five times with CCC at a

concentration of 1000 ppm, SADH at a concentration of 2500

ppm or BOA at a concentration of 25 ppm considerably

increased flowering and production of lemons (Monselise et al.,

1966).

Paclobutrazal (cultar) at the rate of 18 g tree-1, when applied at

the time of imposition of stress (Research Highlights of NRCC,

2005).

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SWEETORANGE

Rao(1961) observed that in Sathgudi Orange, IAA (15 ppm), 2, 4-D (10

ppm), NAA (5 and 15 ppm) and beta-naphthoxyacetic acid (10 and 15 ppm)

sprayed at bud stage significantly increased fruit set.

MANDARIN: GA 40 ppm and NAA 40 ppm have also been reported to

increase fruit set in Ladui mandarin (pastel and Soni, 1972).

Sweet orange (Cv. Washington Navel) plants were subjected to low

preflowering temperature (day/night, 15/10oC), which had resulted in delayed full

bloom by (28 days) and poor fruit set. A small increase in root temperature duringflower development to 16C (at 15/10oC) mitigated the adverse effect of low

day/night temperature on subsequent fruit set (Moss, 1974).

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For inducting of Hasta Bahar in acid lime in themonth of October- November, two sprays of

chloromequat chloride (CCC, Cycocel) at 15 days

interval or stem girdling at 0.3 cm width was

effective in giving good crop of acid lime in peaksummer months

(Research Highlights of NRCC, 2005).

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Anthesis

9.00AM - 12.00PMTerminal bud, leaf less flowers opens early

Flower exposed to sun opens early

Dehiscence

Dehiscence of anthers in citrus takes place at different times

Low humidity and high temperature are found to influence

dehiscence of anthers

High temperature accelerates the dehiscence of anthers

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Stigma receptivity

In general stigma receptivity in various citrusvarieties starts 2- 3 days earlier to anthesis withmaximum receptivity on the day of anthesis

Oozing of gummy substance on the stigmatic surfaceis the indication of stigma receptivity in citrus

Duration of stigma receptivity is influenced byprevailing weather conditions also in dry spring it isshorter than the moist spring

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Pollination

The citrus flowers are

hermaphrodite and homogamous.

A number of citrus cultivars areself incompatable and some are

cross incompatable. Under such

conditions for regular and consist ant

production of an adequate source of

pollen in addition to the pollinating

agents are very essential ( Syam

singh et al.,2001)

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FRUIT SET

1,00,000 2,00,000 flowers on maturetree

Only 1-2% of these flowers will produce

fruits

Time of anthesis is also linked to

percentage initial fruit set. Flowers open

early in the bloom period have muchlower fruit set than those open latter.

Citrus fruits develop very slowly it takes

6 13 months

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Size and number of leaves related to size of fruit

Petal fall off, drying stigma and green ovary indicate

the success of fruit set

Washington navel - sterile pollen

Lemons - more imperfect flowers

Pumellos - self incompatability

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Factors responsible for poor fruit set are pollen sterility, seedlessness,

embryosac sterility and self incompatability

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SN : Vitis vinefera

Family : Vitaceae

Inflorescence : Panicle

Fruit : Berry

GRAPE

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Flowering period

SI : 1. Apr - May

2. Oct - Nov

NI : Mar Apr

Flowering on current season growth during warmseason in NI were as the cold season in SI

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Flowering habit

Fruit buds in grape

vine are lateral,

unfolding to

produce leafy shootsthat terminate in

flower clusters

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Inflorescence

Much branchedcluster,each branchending in a terminal

flower.The inflorescence is

borne on opposite to theleaf and emerge with the

leaves when the shootsstart growing.

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Flower

Calyx :5 sepals, green,soon after

bunches appear the sepals stop

growth and dries up.

Corolla :called as calyptra 5

(greenish petals which are united

at tip therefore flower opens from

base, gets detached and drops off as

a small cap at the time ofblooming)

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Androecium :5 stamens with introse anther. At the base and between filaments

there are pad like nectaries. which produce sweet and odorous nectar. Stamens are

pollen bearing organ of flowers, stamens are opposite the petals in the arrangement

of the floral parts, small filament is present to the stamen,at the tip anther present

Gynoecium :stigma is coated with a sweet and sticky solution secreted from it to

hold the pollen grains falling on it. Ovary is bilocular with 2 ovules in each locules

Perfect Pistillate Staminate

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Anthesis

The time between leafing out and bloom is usually after 8weeks

8.00AM - 9.00AM (SI)

7.00AM - 8.00AM (NI)

Anthesis decreases during

high temperatures

Time taken for completion of anthesis varied

from half a minute to one day depending upon

the variety

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Dehiscence

5 minutes more or less same as anthesis

The walls of each lateral pair of loculi break away by their

inner and thin walled margins throwing pollen grains of the

both together toward the stigma

Stigma receptivity

This is a varietal character in grape

Stigma receptive one day before and after anthesis anddisappears on the third day

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FRUIT SET

Grape cultivar varies markedly in the extent to the fruit setting

The ratio of set berries to the number of flowers in a flower

cluster is the real measure of fruit set

Fruit set is directly proportional to theno.of mature leavesand is

reduced by the presence of immature leaves and shoot tip mainly

because the developing leaves and shoot tips are much stronger

sink for the movement of photosynthates during flower

development

The stage at which the unfertilized ovaries (small berries)

abscise is called theshatter stage

P th

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Parthenocarpy

Stimulative parthenocarpy :Black corinth

There is no ovule development beyond the time of bloom, due to

nutritional stimulous parthenocarpy may occurs.

Stenospermocarpy: Sultania

Munakka

Thompson seedless

Fertilization occurs but the embryo subsequently aborts

Empty seededness :ChaouchEndosperm shrrivelled and degenarated and leaving seeds more or

less shallow

Stages of development

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Stages of development

Bud swelling, doeskin stage with

brownish wool clearly visible

First leaf unfolded and spread

away from shoot

Five to six leaves

unfolded,

inflorescence

clearly visible 3

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Inflorescence fully

developed

Early flowering: 25% of caps

fallen

Late flowering: 80% of

caps fallen

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Fruit set: young fruits begin to swell Beginning of berry touch

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Noticeable loss of green colour also

called "Veraison" Berries ripe for harvest

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