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Dr. Lalit Kumar, Senior Scientist , ICAR-Indian Institute of Pulses Research

posted Oct 2, 2015, 1:01 AM by IBM 2016   [ updated Oct 28, 2015, 4:08 AM ]
Title: Secondary metabolite of plants: role in survival of plants against biotic stresses and maintaining ecosystem biodiversity

Abstract: Animals, plants and microorganisms are important elements of every natural ecosystem. These living creatures interact continuously in a variety of complex relationships under fluctuating environmental conditions, in order to maintain or increase stability within the ecosystem. Plants are known to interact with other component of ecosystem by being release of certain chemicals via their secondary metabolic reactions which are known to involved in the environmental complex as a manager of natural ecosystems. Secondary metabolites are known to act as important defenses agents against predators, competitors and pathogens. Since, microorganism such as fungi, bacteria, viruses, and nematodes are integral parts of agro-ecosystems hence these organisms affect the agro-ecosystems with their harmfull, neutral or beneficial effects thus the pivotal roles of secondary metabolites in the determination of plant diversity, dominance, succession, and climax of natural vegetation and in the plant productivity of agro-ecosystems can not be ignored. For better agro-ecosystems productivity control of predators, weeds and disease-causing organisms is always remained an essential component in every crop production system. Since World War II, numerous synthetic pesticides have been developed and used for control of crop pests. But unfortunately most of the chemical pesticides killed not only the target species of pests but also other non-harmful or beneficial organisms. Apart from this the overuse of synthetic agrochemicals often causes environmental hazards, an imbalance of soil microorganisms, nutrient deficiency, and change of soil physicochemical properties, resulting not only in a decrease of crop productivity but also proved detrimental to the microbial biodiversity in agro-ecosystems. The incorporation of allelopathic substances into agricultural management may reduce the use of synthetic herbicides, fungicides, and insecticides and lessen environmental deterioration. Scientists in many different habitats around the world have demonstrated the role of secondary metabolites (Allelopathic compounds) of plants in mitigating biotic stresses such as weed infestation, predators and pathogen attack etc. It is known that most volatile compounds, such as terpenoids, are released from plants in drought areas. In contrast, water-borne phytotoxins, such as phenolics, flavonoids, or alkaloids, are released from plants in humid zone areas. Studies conducted at IIPR, Kanpur also revealed good control of fungal diseases of pulse crops by root exuded allelochemicals of sorghum plants whereas, the chemicals released via the root of sesame plant was found very active against purple nutsedge and other weeds. Thus, the allelopathic based approaches has immense applicability in plant biodiversity and Sustainable Agriculture. For future, better understanding about the diversity of secondary metabolites and what environmental factors trigger increased production of these compounds, novel and ecologically relevant methodologies are needed to develop and subsequently applied to studies of allelopathy, antipredation, anifouling, antimicrobial, and other possible functions of secondary metabolites. The assumption is that if we can understand the function of these molecules and how they can alter biodiversity at the genetic, species and ecosystem level, we can ultimately underpin the processes that underlie ecosystem functionality.