Bacillus spp. for seed biopriming to enhance growth in transplants of Solanaceous vegetable crops

Abstract

The experimental work entitled “Bacillus spp. for seed biopriming to enhance growth in transplants of solanaceous vegetable crops” was done at Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram during academic year 2019-21. Objective of study was to assess the effectiveness of biopriming with spore forming bacilli for plant growth promotion in transplants of solanaceous vegetable crops such as tomato, brinjal and chilli. In vitro as well as in vivo experiments were conducted in this study. In vitro studies included characterization of the bioagents viz, B. pumilus VLY17, B. amyloliquefaciens VLY24 and B. velezensis PCSE10 for plant growth promoting parameters. IAA production was assessed in presence and absence of tryptophan and it was found that B. pumilus VLY17 produced maximum IAA (23.344μgmL1 ) in presence of tryptophan whereas in the absence of tryptophan, B. amyloliquefaciens VLY24 produced maximum IAA (15.072 μgmL-1 ). Ammonia production was observed in B. amyloliquefaciens VLY24 and B. velezensis PCSE10. Direct and indirect antagonism against Pythium sp. was done by dual culture plate assay and agar well diffusion assay respectively. All three bioagents showed inhibitory effects. In agar well diffusion assay, unmeasurable inhibitory zone was observed in case of B. velezensis PCSE10. Roll towel technique was performed to assess seedling vigour of tomato, brinjal and chilli seeds bioprimed with bacterial bioagents and their consortium against hydroprimed and untreated control. In tomato, maximum seedling vigour was observed in seeds treated with B. pumilus VLY17 (556.75). In brinjal, B. amyloliquefaciens VLY24 treated seeds showed maximum vigour (860.5) followed by consortium treatment (828). In chilli, consortial treatment (970) followed by B. pumilus VLY17 (951.25) treatment showed maximum vigour index. In vivo studies were done by raising treated seeds of tomato, brinjal and chilli in protrays. In tomato, three of the treatments showed superior results in growth promotion viz, consortium treatment followed by B. pumilus VLY17 and B. amyloliquefaciens VLY24. In brinjal, B. velezensis PCSE10 showed best results in majority of plant growth promoting traits. In chilli, B. pumilus VLY17 and B. amyloliquefaciens VLY24 showed superior results. Root colonization studies were also done and all the three bioagents were found to be effective root colonizers in all the three crops studied. Results of this study lead to the conclusion that the three endospore formers are highly effective as biopriming agents for enhancing plant growth promotion and development in solanaceous vegetable crops under nursery conditions.