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The present investigation was carried out to evaluate the potential of chitosan alone and in combination with various agricultural wastes for the management of rootknot nematode, Meloidogyne incognita on eggplant cv. ‘BR-112’ under greenhouse conditions. The results showed that chitosan as a single or joint treatment with agricultural wastes significantly (p ≤ 0.05) reduced root-knot indices, and the nematode population in soil. As a result, of this, the growth and growth yielding attributes of eggplant were remarkably augmented. Chitosan as an elicitor induced plant mediated systemic resistance against M. incognita in eggplant. The results of the study demonstrated that maximum reduction in eggmass/root, eggs/eggmasses, nematode population and root-knot indices, was acquired by the treatments: chitosan + onion and chitosan + mentha. It was followed by chitosan + Brassica, chitosan + urad and chitosan + coconut whereas, chitosan combined with corn cob waste was found to be the least effective when compared to the control. The application of chitosan alone was effective but not very satisfactory. Compared to the control applications of all the treatments significantly increased plant growth in terms of length, fresh and dry weights, pollen fertility, yield and biochemical parameters such as chlorophyll, carotenoid content and antioxidant enzymes. This may have been due to the eliciting activity of chitosan, causing systemic resistance in the plant and the release of various toxic chemical compounds during decomposition which have lethal effects against the second stage juveniles of M. incognita and nematode multiplication.

This review deals with the mechanism of antagonistic action of bacterial and fungal biocontrol agents such as the production of antibiotics, siderophores, enzyme secretion, competition for nutrition, plant growth promotion by rhizosphere microorganism. The utilisation of synthetic pesticides has been the predominant control processor for diseases brought about by phytopathogenic microorganisms. Notwithstanding, their open and improper application in intensive agriculture has realised issues that have prompted ecological contamination, considerable residues in agricultural products and phytopathogen resistance. They are likewise disrupting the quantity of beneficial microorganism which is available in the soil and capable of expanding soil fertility. Along these lines, there is a need to look through the option of synthetic pesticides that are safe, environmental and monetarily feasible to confront this problem. Biocontrol agent's utilisation is the best alternative method to control the different kinds of diseases, such as nematode infestation, fungal pathogen and bacterial pathogen. Nowadays, biocontrol agents assume a significant role in the field of agriculture. It is a financially savvy, environment-friendly and inhibits the advancement of pathogenic microorganism sustainably. This review emphasises the role of biocontrol agents against different pathogenic microorganisms and their significance potentiality to improve plant growth and enhance defence system of plants. [ABSTRACT FROM AUTHOR]