Seed treatments and seedling root soaking in biological agents improved plant growth and reduced bacterial leaf blight disease incidence in rice

Abstract

Bacterial leaf blight (BLB) is caused by Xanthomonas oryzae pv. oryzae (Xoo), a seed-soil-air-borne pathogen that can reduce 60% of rice yield. The primary study intended to investigate the effect of seed treatments and root soaking with biological agents (a mixture of Pseudomonas diminuta and Bacillus subtilis) on plant growth and the severity of BLB in a greenhouse. A split-plot experimental design was used with seed treatments as the main plot: negative control, positive control (Xoo inoculated), bactericide (streptomycin sulfate 20%) 0.2%, biopriming with biological agents 108 CFU ml−1, matriconditioning plus bactericide 0.2%, biomatriconditioning with biological agents 108 CFU ml−1. The subplots were root soaking: untreated, bactericide 0.1%, 0.2%, 0.4%, 0.6%; biological agents 106 CFU ml−1, 108 CFU ml−1, and 1010 CFU ml−1. Biomatriconditioning reduced the BLB incidence three weeks after sowing from 10.6% to 1.7% and increased plant height four weeks after transplanting (WAT). Biomatriconditioning followed by root soaking in the biological agents or 0.4 % bactericide increased plant dry weight 3 WAT. Biomatriconditioning or root soaking in the biological agents (106 CFU ml−1) provided the most significant number of tillers 4 WAT.