Impact of seaweeds on fluorescent Pseudomonas and their role in suppressing the root diseases of soybean and pepper

Abstract

Incorporation of organic matter in soil before sowing of seeds or transplanting the seedlings has been reported to increase microbial activity in soil specially fluorescent Pseudomonas that play a vital role in suppressing the root rotting fungi and parasitic nematodes invading plant roots. In this study dry powder of seaweeds Sargassum binderi, S. tenerrimum, Halimeda tuna, Stoechospermum marginatum, Padina tetrastromatica, Stokeyia indica and Solieria robusta were applied as soil amendment two weeks before the? sowing of soybean seeds or transplanting of pepper seedlings in screen house and or in field experiments. Application of some seaweeds and Topsin-M (fungicide) and carbofuran (nematicide) showed more or less similar suppressive effect on root rotting fungi Macrophomina phaseolina, Rhizoctonia solani, Fusarium solani and root knot nematode Meloidogyne javanica on soybean and pepper plants. Seaweed also showed a positive effect on plant growth by enhancing fresh shoot weight and plant height. Incorporation of seaweeds in soil increased population of fluorescent Pseudomonas around the roots of soybean and pepper as compared to non-seaweed control. However the increased population of fluorescent Pseudomonas around the roots did not correlate with disease suppression.