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Sesame and Sesame and Sesame and Sesame and SSSSorghumorghumorghumorghum: : : : BioBioBioBio----componentcomponentcomponentcomponentssss of of of of Organic FOrganic FOrganic FOrganic Farming arming arming arming EEEEvadingvadingvadingvading Weeds and Weeds and Weeds and Weeds and

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Lalit KumarLalit KumarLalit KumarLalit Kumar, , , , Ummed SinghUmmed SinghUmmed SinghUmmed Singh****, , , , P.P.P.P. S. BasuS. BasuS. BasuS. Basu,,,, M. Senthil KumarM. Senthil KumarM. Senthil KumarM. Senthil Kumar and G.and G.and G.and G. K. SrivastavaK. SrivastavaK. SrivastavaK. Srivastava

Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India-208 024 *Email of corresponding author: *Email of corresponding author: *Email of corresponding author: *Email of corresponding author: drummedsingh@gmail.comdrummedsingh@gmail.comdrummedsingh@gmail.comdrummedsingh@gmail.com

Introduction Introduction Introduction Introduction

According to International Federation of Organic Agriculture Movements "Organic agriculture is

a production system that sustains the health of soils, ecosystems and people. It relies on ecological

processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with

adverse effects. Organic agriculture combines tradition, innovation and science to benefit the

shared environment and promote fair relationships and a good quality of life for all involved".

Therefore, Organic farming is a form of agriculture that relies on techniques such as crop

rotation, green manure, compost and biological pest control. Organic farming uses fertilizers and

pesticides but excludes or strictly limits the use of synthetic fertilizers, pesticides (which include

herbicides, insecticides and fungicides), plant growth regulators such as hormones, livestock

antibiotics, food additives, genetically modified organisms, human sewage sludge, and nano-

materials which do not only endangered the ecosystem but also encouraged resistance in weeds

and pests. Thus, for minimizing the weed and pest infestation, organic standards require rotation

of annual crops that means a single crop cannot be grown in the same location without a

different intervening crop. Organic crop rotations frequently include weed and pathogen

suppressive cover crops and crops with dissimilar life cycles to discourage weeds and pathogens

associated with a particular crop. Now days it is very well recognized that certain plant species

discourage insects and pathogens and even the weeds through the release of organic chemicals

Many crops have been reported for showing their allelopathic properties at one time or

another. In this series sorghum (Sorghum bicolor L) and sesame (Sesamum indicum) are

known for interference on other plants and on disease causing organisms. Including

these crops in crop sequence are immensely required to maintain sustained productivity

and discouraging weeds, pathogens and insect.

Popular Kheti Volume -1, Issue-4 (October-December), 2013

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ISSN:2321-0001 1(4) 2013

Special on

Organic Farming

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generally known as allelochemicals. These chemicals can be directly and continuously released

by the donor plants in their immediate environment as water leachates volatiles in the air or root

exudates in soil - or they can be the microbial degradation products of plant residues. In this

context, many crops have been reported for showing their allelopathic properties at one time or

another and farmers report that some crops such as oat (Avena sativa L) seem to clean fields of

weeds better than other whereas the other important crop in this series includes: wheat

(Triticum aestivum L.), barley (Hordeum vulgare L.), cereal rye (Secale cereale ), brassicas

(Brassica spp.), red clover (Trifolium spp)., yellow sweet clover (Trifolium spp)., trefoil (Lotus

corniculatus), vetch (Vicia ervilia), buck wheat (Fagopyrium esculentum L.), lucerne (Medicago

sativa), rice (Oryza sativa L), beet (Beta vulgaris L.), lupin (Lupinus lutens L.), sorghum

(Sorghum bicolor L) and sesame (Sesamum indicum). Knowledge of this form of plant

interference on other plants and on disease causing organisms has also been known by the

farmers since prehistoric time. Thus in balanced agriculture settings, manipulation of cropping

pattern and sequence through mixed cropping or crop rotation by including the strong

allelopathic crops such as sesame and sorghum are immensely required frequently after a certain

period of time. This kind of crop sequence manipulation would not only be able to maintain

sustained productivity but also be helpful in discouraging weeds, pathogens and insect. As per

our opinion this kind of approach bears more fruit since achievement of 100% control of weeds

probably is an unrealistic objective hence this aspiration can be considered as a blamed

ecosystem. However, resistance, allelopathic potential, and other noxious characteristics of weeds

are to be avoided and a less polluted environment should be our final and ultimate goal.

Sesame and Sesame and Sesame and Sesame and WeedWeedWeedWeed

Sesame (Sesamum indicum) is native to the Old World tropics and is one of the oldest cultivated

plants in the world. In India, sesame is commonly known as Til (Hindi) and also entered into the

category of most ancient cultivated crops. Except high hills, sesame can be cultivated throughout

the country. The major recognized states of its cultivation are Uttar Pradesh, Rajasthan, Madhya

Pradesh, Tamil Nadu, Maharashtra, Andhra Pradesh, Karnataka and Gujarat. In our country it is

mainly grown to extract edible oil used in cooking, salad and manufacturing of marginarine. In

India about 80% seeds of total production being use for oil extraction, 2% is retained for planting

purposes and nearly 18 percent are utilized for direct edible purposes. Apart from several

culinary values this plant is also known as a good source of various secondary metabolites mainly,

polyphenols, alkaloids, flavanoids, terpenoids, glycosides and various amino acids out of those

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many of them are observed to be herbicidal active against a variety weeds. Though the farmers,

in India, were not aware of its chemical based mechanism of herbicidal action but were well

verse, since ancient, with the weed suppression ability of this crop observed by them especially

against the Purple nutsedge (Cyprus rotundus). Subsequently, the allelopathic effect of this crop

against various weeds with special emphasis to Purple nutsedge was also evaluated scientifically

in several field experiments. Fractionated extracts and purified chemical components of root

exudates of intact live plant of sesame were also identified for their strong herbicidal action

against Cyprus rotundus and several other weeds. Against Cyprus rotundus, the exuded chemicals

were not only found tremendously active as germination inhibitor and growth suppressant but

also observed to pose comparatively predominant impact on the roots and new tuber

development tendencies of the weed. About 90-99% reduction in all the vegetative and root

growth concern parameters viz., germination, total biomass, root biomass, new tuber

development and their biomass and viability etc. in treatments of some of the lipophilic nature of

the chemical fractions confirmed that the chemicals release via roots of sesame as exudates not

only have their adverse effect on the germination of tubers and vegetative growth of survived

plants but also possess tremendous ability to destroy the weed via degrading their roots and not

allowing the survived roots to form many tubers on them. Therefore, the finding confirmed that

the allelochemical of sesame put an effective barrier against propagation of this weed since the

weed propagates in agricultural fields by continuously forming the tubers and hence can play a

key role in effective management of this weed. Apart from this approximately 60-80% reduction

in germinations and vegetative growth of certain other weeds viz., lambsquarters (Chenopodium

album, L.), scarlet pimpernel (Anagalis arvensis, L.),white sweet clover (Melilotus alba, L.

Medik.), corn flurry (Spergula arvensis, L.), fumitory (Fumaria parviflora, Lam.), and common

vetch (Vicia sativa, L.) too indicates that root exuded chemicals of sesame are not only diverse in

chemical nature but also differ in their modus-operandi which in turn helps in minimizing the

weed population in agricultural fields. Thus, owing to be of its great weed suppression

potentiality this crop can be advocated as a good component of organic farming in relation to

curtail weed population below threshold level. Since, organic weed management promotes weed

suppression, rather than weed elimination therefore, the weed minimization goal can simply be

achieved if we include the sesame crop in crop rotations frequently over a certain period of time.

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Allelopathic influences of crops and other plants that influence the weed vigor and populations

have been shown in the figures below.

Sorghum and Sorghum and Sorghum and Sorghum and WeedWeedWeedWeed

Sorghum has been, for centuries, one of the most important staple foods for millions of poor rural

people in the semiarid tropics of Asia and Africa. Presently it is the fifth most important cereal

crop grown in the world. In India, sorghum is popularly known as jowar and is the most

important food and fodder crop of dry land agriculture. In India, sorghum grain is eaten either by

breaking the grain and cooking it in the same way as rice or by grinding it into flour and

preparing ‘chapattis’. Sorghum can be grown under a variety of soils and a wide range of climatic

conditions although ideally it requires warm climate. This crop, in general, is a very competitive

Effect of root exuded lipophilic chemical fraction of sesame on C. Rotundas vegetative growth. Root exudates were collected by growing the sesame plants in root exudate trapping system. Collected exudates were fractionated and lipophilic fraction was removed. In treatments the soil of pots was treated with 90 &75 µg ml-1 concentrations of the isolated fraction.

C. rotundus growth in sesame and rose pots. Since the root exudates of rose were found beneficial to the weed therefore 10 days old weed plants in rose pots are very vigor. But the height of one month old weed in sesame pot is very meager that confirm the antagonist effect of sesame root exudates on C. rotundus.

Control Treatments

90 µg ml-1 concentration of the lipophilic compounds of sesame root exudates was found to reduce root biomass and their new tuber development tendencies up to the extent of 90-95%.

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crop, and does well in competition with weeds in narrow rows. It produces various major and

minor benzoquinone derivatives the important one of them is sorgoleone {2- hydroxy- 5-

methoxy- 3- [(8'Z, ll'Z)- 8' ,1l' ,14' -pentadecatriene]- p- benzoquinon}, which the plant uses to

combat weeds. The chemical is so effective in preventing the growth of weeds that it sometime

prohibits the growth of other crops harvested on the same field. Apart from the sorgoleone, other

water soluble allelochemicals of this crop which are phytotoxic to the growth of certain weeds

like Phalaris minor Retz., Chenopodium album L., Rumex dentatus L. and Convolvulus arvensis

L. has also been reported. Further, incorporation of sorghum roots into soil suppressed the weed

biomass by 25–50% and increased wheat yields by 7–8%. Reports also indicate that the

application of 5% sorgaab (water extract of mature stalk of Sorghum plants obtained after soaking

in water for 24 hour and sprayed as a natural herbicide) increase wheat yields by 14% and

suppressed weed biomass by 20–40% when applied 30 days after sowing. Under semiarid region

of Punjab, the allelopathic effect of sorghum against weeds of irrigated wheat was also reported

and the concern report indicates that soil incorporation of sorghum stalks at 2, 4 and 6 Mg ha−1

reduced weed dry weight by 42, 48 and 56%, respectively. Experiments conducted at IIPR,

Kanpur also showed a very good impact of root exuded chemicals, taken by growing the sorghum

plants in root exudate trapping system, against a variety of weeds viz, purple nut sedge,

lambsquarters, scarlet pimpernel, white sweet clover, corn flurry, fumitory and common vetch.

Therefore, it is clear that this crop also possess good potentiality against weeds and inclusion of

this crop in any form in agricultural settings would certainly be helpful in reducing the weed

population.

Sorghum and Sorghum and Sorghum and Sorghum and PathogensPathogensPathogensPathogens

Besides constituting of the herbicidal nature of the allelocompounds the sorghum plant are also

found to contain a variety of secondary metabolites which are highly toxic to numerous

pathogens. This series of secondary metabolites comprises of several classes of water soluble

compounds particularly phenolic acids (ferulic, p-coumaric, syringic and p-hydroxybenzoic acids

etc.) in decomposing residues of sorghum. Besides phenolics, recently several derivatives of 3-

deoxyanthocyanidins viz., apigeniidin, 7-methoxyapigeninidin, 5, 7-dimethoxyapigeninidin,

luteolinidin etc. are also identified as effective chemicals which provide defense mechanism to

sorghum plant against pathogens attack. Germinated seedlings of sorghum are also observed to

accumulate a high level of 3-deoxyanthocyanidins phytoalexins. Certain new phytoalexins

closely mimic in their chemical structures with the already reported 3-deoxyanthocyanidines

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were also observed by authors in root exudates of sorghum plants collected via root exudate

trapping system. These newly isolated chemical compounds were observed very toxic (LD50 17-

240 µg-1) to seven pathogens viz., Fusarium. udum, F. oxysporum f. sp. Ciceri (wilt), R. bataticola

(dry root), S. rolfsii (collar rot), Sclerotinia sclerotiorum (stem rot), A. alternata (leaf spot) and

Choenephora cucurbitarum generally attack on pulse crops and cause heavy economic losses to

the farmers. The fungicidal effect of this crop was not only observed in laboratory experiments

but the measurable impact of this crop against wilt and other diseases of pulse also visualized in

several field experiments especially in those if either the sorghum was grown as a mixture of

crops or as a preceding crop in same field. In laboratory experiments, the isolated chemicals were

found so effective that they do not only degenerate the morphology of the mycelium of treated

fungus but also causes heavy reduction in number and size of conidia /sclerotia and their

viability. Therefore, this kind of action indicates that the sorghum plant have capacity to destroy

the pathogens completely since fungus survived by making these resting bodies under adverse

environmental situations. Hence, besides the control of weeds the crop is also efficient in

completely destroying the variety of plant pathogenic pathogens.

Impact of sorghum chemicals on colony growth and mycelium morphology of S. rolfsii pathogen

Chemical Treated: S, sclerotiorum conodia are not germinated

Untreated: S. sclerotiorum conodia are germinated

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ConclusionConclusionConclusionConclusion

Organic farming system in India is not new and is being followed since ancient. It is a method of

farming system which primarily aimed at cultivating the land and raising crops in such a way, as

to keep the soil alive and in good health. Since intensive cropping has now become a very

common practice in various parts of the world therefore, selection of suitable crops and crop

sequences can successfully play a key role to get rid of weed and pathogens infestation to a

greater extent without much using of the environmental hazardous synthetic chemicals which

are directly or indirectly causing negative impact on quality of the produce, environment and

overall human health. At the same time achieving the food security to feed the burgeoning

population of the world, has now become a challenge to mankind and to accomplish this, yield

maximization and simultaneously to chock out the environmental friendly tactics to prevent the

losses caused by weed and pathogens infestations are only the solutions. As it is clear from the

above discussion that there are immense prospects of allelopathic mechanism in relation to

manage weeds and pathogens infestation effectively in agricultural fields. In present scenario

Allelochemicals and allelopathic interactions of several plants and crop sequences have not only

been identified but the activities of the chemicals produced by the plants/crops have also been

established. In this respect sorghum and sesame crops can be considered as ideal materials to

fulfill the requirements of weeds and diseases control. Compared with other crops, these two

crops (Sorghum and Sesame) are well known for their tolerance power against various abiotic

factors such as drought tolerance, water logging etc. Both are also tolerant to salinity and can be

grown successfully in soils with salt concentration up to 10,000 ppm and the pH ranges from 5.5

to 8.5. Moreover, both can fit well in various prevalent crop rotations in our country. Therefore,

taking all these attributes in view inclusion of sorghum and sesame in the cropping system not

only suppress weeds but also minimizes disease infestation to some extent. Hence, farmers can

harness the extra benefits lies with them in terms of weed and diseases suppression qualities.