Allelochemicals (1)

Allelochemicals (1)

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  ICAR-NDRI ALLELOCHEMICALS SUBMITTED TO: Dr.Hardev Ram sir Scientist (Agronomy) SUBMITTED BY: Pramod Kumar Tiwari M.Sc.(Agronomy)
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  INTRODUCTION Since the firstimplementation of synthetic herbicides in crop protection systems Weeds have continuously developed resistance. As a main reason of such evolution, Long –lasting exploi-tation of herbicieds with one target site in plants is considered. This has been the case with the FRIST widely – used triazine herbicides, PS INHIBITORS Which have effectively eliminated. WHAT IS ALLELOCHEMICALS? Allelochemicals are the product of secondary metabolism and are non nutritional primary metabolites. These compounds belong to numerous chemical groups. “ Allelochemicals also called as Allelopathy “ Molish (1937) coined the term stimulatory or inhibitory. (Allelopathy)  Greek word “Allelon” or “allelo” = mutual or each other “pathos” or “patho” = suffering or to suffer It is defined as the intraction between plants and micro-organism by a variety of compounds usually referred to as allelopathy, allelochemicals, or allelopathic compounds. All allelochemicals are secondary metabolites but all secondary metabolites are not allelochemicals ”
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  CLASIFICATION OF ALLELOCHEMICALS Allelochemicalscan be classified in to ten categories acc. to their different structures and properties.  water soluble organism acids , straight – chain alcohols , aliphatic. Simple latons. Long-chain fatty acids. Cuinines. Phenolics. Cinnamic acid and its derivatives. Counarins. Flavonoids. Tannins. Terpenoids.
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  ADVANTAGES OF ALLELOCHEMICALS Modeof action of some allelochemicals is similar to synthetic herbicides.  However, in the perspective of bioherbicides based on allelopathins, effects caused by these compounds on target plants are also classified as “phytotoxic”. Most of allelopathins are totally or partially water-soluble which makes them easier to apply without additional surfactants. Their chemical structure is more environmentally friendly than synthetic ones. The diversity of allelopathins makes them promising tools possessing specific properties in discovering novel, specific target sites in acceptor plants.
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  The pathway ofallelochemicals released into the environment.
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  PROBLEMS WHICH ISCREATED BY ALLELOPATHY IN AGRICULTURE Reduced nutrient uptake. Weed seed decomposition delayed/prevented. Poor success on replanting of tree crops. Failure of vegetative propagation. Suppression effect from tree. Soil sickness. Auto toxicity under same cropping system. Increased crop weed interference.  increased susceptibility to pest and diseases. Reduced nitrification and BNF.
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  Sources of allelochemicals- Plantresidues decomposition   Roots(exudates and decomposition )  Leaves  leaf leachates  leaf litter  Volatilization ( from leaves, flower ,whole plant)  Seed leachates
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  Allelopathic interactions betweenplants. Multi site action of allelochemicals.
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  Application of allelopathyin weed management Development of novel bio pesticides.  Bialaphos.  cinmethylin.  AAL toxins.  Adoption of crops or crop cultivars more allelopathic to weeds.  Utilizing a companion crop plant that is selectively to allelopathic to weeds.  Mulching.