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ALLELOPATHY BY HIMANSHU

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HIMANSHU BHATT HIMANSHU BHATT Id No.-39684 Id No.-39684 B.Sc. Ag Final YEAR B.Sc. Ag Final YEAR Group- C Group- C SUBMITTED TO : RAWE COORDINATORS
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Page 1: ALLELOPATHY BY HIMANSHU

HIMANSHU BHATTHIMANSHU BHATTId No.-39684Id No.-39684

B.Sc. Ag Final YEARB.Sc. Ag Final YEARGroup- CGroup- CSUBMITTED TO:

RAWE COORDINATORS

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INTRODUCTON• Allelopathy is derived from two greek words Allelopathy is derived from two greek words

“allelon or allele” means “mutual or each other” “allelon or allele” means “mutual or each other” and “pathos” means “suffering or to suffer.” and “pathos” means “suffering or to suffer.”

• Hans Molisch (1937)Hans Molisch (1937), plant physiologist, , plant physiologist, University of Vienna, Austria, coined the term University of Vienna, Austria, coined the term allelopathyallelopathy

• It was first reported in alfa-alfa, and the first It was first reported in alfa-alfa, and the first allelochemical was extracted from walnut.allelochemical was extracted from walnut.

• Actually, it is the process involving secondary Actually, it is the process involving secondary metabolites, produced by algae, bacteria, plants , metabolites, produced by algae, bacteria, plants , which influence the growth of the other or same which influence the growth of the other or same species.species.

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• The central principle in Allelopathy arises from the fact that plants The central principle in Allelopathy arises from the fact that plants and microorganisms collectively produce thousands of chemicals, and and microorganisms collectively produce thousands of chemicals, and many of these chemicals are released from the producing organism many of these chemicals are released from the producing organism by leaching, by leaching, exudationexudation, , volatilizationvolatilization, or decomposition processes. , or decomposition processes. Subsequently, some of these Subsequently, some of these compoundscompounds (known as allelochemicals) (known as allelochemicals) alter the growth or alter the growth or physiologicalphysiological functions of organisms that functions of organisms that encounter them during growth. encounter them during growth.

• For example, almost pure droplets of For example, almost pure droplets of sorgoleonesorgoleone (a quinone) are (a quinone) are exuded from the roots of Sorghum species, which inhibits growth in exuded from the roots of Sorghum species, which inhibits growth in plants that contact it by blocking photosynthesis and respiration.plants that contact it by blocking photosynthesis and respiration.

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Cinnamic and benzoic acids, flavonoids , and various terpenes are the most commonly found allelochemicals,. A few allelo-chemicals have been developed as herbicides and pesticides, and it may be possible to genetically engineer a crop to produce its own herbicides.

TYPES OF ALLELOPATHYa) Alloallelopathy and Autoallelopathyb) True allelopathy and Functional allelopathy

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Crop against other crops: • Examples:Examples:• Sunflower has been founSunflower has been foundd allelopathic to groundnut allelopathic to groundnut

under under intercropping intercropping situationsituation• Tree crops like Tree crops like EucalyptusEucalyptus also shows some also shows some

allelopathicallelopathic interactions to vegetables and some field interactions to vegetables and some field crops grown as intercrop with it.crops grown as intercrop with it.

• Crop residues of lentil are phytotoxic to wheat and of Crop residues of lentil are phytotoxic to wheat and of sunflower and mustard to several cropssunflower and mustard to several crops

• Sorghum is allelopathic to wheat and sweet potato to Sorghum is allelopathic to wheat and sweet potato to cowpea.cowpea.

• Mung/ green gram and cowpea are stimulatory to the Mung/ green gram and cowpea are stimulatory to the growth of wheat.growth of wheat.

FORMS OF ALLELOPATHIC INTERACTIONS

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• Crop against weeds: • Examples:Examples:• Sorghum releases hydrocynic acid (HCN) and suppresses many Sorghum releases hydrocynic acid (HCN) and suppresses many

weeds growing in vicinity. weeds growing in vicinity. • Barley produces “gramine” an alkaloid, which inhibits weed growth Barley produces “gramine” an alkaloid, which inhibits weed growth

S.No. Crops Weed species

1 Maize Chenopodium album, Amaranthus retroflexus

2 Sorghum Setaris viridis, Bromus pectinatus, Amaranthus hybridus

3 Cucumber Echinochloa crusgalli

4 Sweet potato Cyperus rotundus, Cyperus esculentus

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Weed against crops:S.No. Weeds Crops

1 Cyperus rotundus Sorghum , soybean

2 Imperata cylindrical Several crops

3 Chinopodium album Alfalfa, cucumber, oat, maize

4 Cirsium arvense Several crops

5 Avena fatua Several crops

Weed against other weedsCassi sericeaCassi sericea, has shown encouraging result to oust parthenium in , has shown encouraging result to oust parthenium in Karnataka stateKarnataka state.

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SOURCES OF ALLELOPATHY

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PLANT CHEMICALS REFERENCE

Secale cereal L.

(Rye)

 

Avena sativa L.

Sorghum bicolor L.

(Sorghum),Triticum aestivum L.

(wheat)

 

Barley

Mungbean

Medicago sativa L.

Chenopodium

 

Cucumis sativus L. (Cucumber)

2,4-dihydroxy-1,4(2H)benzoxazin-3-

one (DIBOA) 2(3H)-

benzoxazolinone (BOA)

Ferulic acid

P-cumaric acid

2,4- Dihydroxy- 7- methoxy-1, 4-

benzoxazin-3-one (DIMBOA)

Hordenine

Hydroxamic acid

Saponins

Ascaridole, alpha-terpinene

Gamma-linolenic acid,

Alpha-asarone

Benzoic and Cinnamic acids

Barnes & Putnam (1987)

 

 

Rice (1984)

 

 

Perez ( 1990)

 

Liu and Lovett (1993)

Corcurea et al. (1992)

Krol et al. (1995)

Corcurea et al. (1992)

 

Yu and Matsui, 1994

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The The Glucoside Glucoside which is present which is present inin wheat, ricewheat, rice, , maize can maize can have many aspects:have many aspects:

• Influence growth of weedInfluence growth of weed• Involve in detoxification of pesticides, Involve in detoxification of pesticides, • Increase the resistance of insects, fungi and Increase the resistance of insects, fungi and

bacteria, in cereals.bacteria, in cereals.• Trigger the reproduction of grass-feeding Trigger the reproduction of grass-feeding

mammals,mammals,• Are mutagenic agentsAre mutagenic agents

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ALLELOPATHIC PROBLEMS IN AGRICULTURE, HORTICULTURE AND FORESTRY

1)1) Soil sicknessSoil sickness2)2) Auto toxicity under same crop monocropping.Auto toxicity under same crop monocropping.3)3) Increased crop- weed interferenceIncreased crop- weed interference4)4) Growing susceptibility of plants to disease/ pestsGrowing susceptibility of plants to disease/ pests5)5) Reduced nitrification and biological nitrogen fixationReduced nitrification and biological nitrogen fixation6)6) Reduced nutrient uptakeReduced nutrient uptake7)7) Weed seed decomposition delayed/ preventedWeed seed decomposition delayed/ prevented8)8) Poor success on replanting of tree cropsPoor success on replanting of tree crops9)9) Failure of vegetative propagation (e.g. grafting, Failure of vegetative propagation (e.g. grafting,

budding)budding)10)10)Suppression effect from treesSuppression effect from trees

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 11. . Modern crops have been selected by breeders for Modern crops have been selected by breeders for desirable agricultural characteristics, which have desirable agricultural characteristics, which have removed allelopathic properties.removed allelopathic properties.

a) Rapid seed germination achieved by selecting a) Rapid seed germination achieved by selecting lines with reduced seed coat inhibitors. Some lines with reduced seed coat inhibitors. Some germination inhibitors also act as germination inhibitors also act as antibiotics/fungicides.antibiotics/fungicides.

b) Increase production of edible parts, allelopathic b) Increase production of edible parts, allelopathic compounds and all other secondary (defensive compounds and all other secondary (defensive metabolites) require energy. Cultivated crops are metabolites) require energy. Cultivated crops are developed for either high sugar content or larger developed for either high sugar content or larger heads of grain or bigger storage roots. heads of grain or bigger storage roots.

INFLUENCES OF ALLELOPATHY IN CONTROLLED OR AGRICULTURAL ECOSYSTEMS

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• c) Other numerous selections for desirable c) Other numerous selections for desirable plant virtues must of necessity reduced plant virtues must of necessity reduced levels of bitterness or other chemical levels of bitterness or other chemical which wild forms make use of for defense.which wild forms make use of for defense.

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2. Using allelopathy in agriculture.2. Using allelopathy in agriculture.• a) In new forests or in reforestation make use a) In new forests or in reforestation make use

of allelopathy by planting a mix of species of allelopathy by planting a mix of species that speed up succession thus preparing the that speed up succession thus preparing the soil for long term support of tree crops.soil for long term support of tree crops.

• b) For nematode and soil born disease control b) For nematode and soil born disease control use rotations with ground covers shown to use rotations with ground covers shown to strongly reduce these problems. strongly reduce these problems.

• Rhodes grass useful for reniform nematodes Rhodes grass useful for reniform nematodes and soybeans for potato scab.and soybeans for potato scab.

POSITIVE ASPECTS

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Helianthus tuberosus, Helianthus tuberosus, a staple food crop in Europe a staple food crop in Europe in past, which has now become a weed, can be in past, which has now become a weed, can be used as method to control weeds, especially used as method to control weeds, especially monocot weeds.monocot weeds.

• Soil+HT @ 25 tonne/ha,Soil+HT @ 25 tonne/ha,• Soil+HT @ 50 tonne/ha.Soil+HT @ 50 tonne/ha.• After 25 days, there is severe impact on weeds After 25 days, there is severe impact on weeds

both during growth period and germination period., both during growth period and germination period., e.g., e.g., Oxalis spp., Phalaris minor, Avena sppOxalis spp., Phalaris minor, Avena spp..

POSITIVE ASPECTS

Chopped radish along with manure have also Chopped radish along with manure have also controlling effect on weeds up to 60% in crops like controlling effect on weeds up to 60% in crops like cotton, soybean.cotton, soybean.

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THE END


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