Efficacy of T harzianum isolates in plant growth promotion and BLB management in rice

Rice crop is highly vulnerable at all stages of growth to different pathogens that affect the quality and quantity of its yield. Among the different diseases, Bacterial blight of rice (Xanthomonas oryzae pv. oryzae), a deadly bacterial disease is among the most destructive affliction of cultivated rice (Oryza sativa and O. glaberrima). In severe epidemics, crop loss may be as high as 75 percent, and millions of hectares of rice are infected annually. Biological control based on antagonism is a potential, non-chemical and eco-friendly approach for managing plant diseases. Biocontrol agents like Trichoderma spp. are acclaimed as effective, eco-friendly and cheap, nullifying the ill effects of chemicals. The present study involved five different isolates of Trichoderma harzianum viz. IRRI-2, IRRI-3, IRRI-4, IRRI-5, IRRI-6 obtained from International Rice Research Institute. Variations were observed while comparing the efficacy of different Trichoderma harzianum isolates, IRRI-5 and IRRI-2 isolates exhibited superior anti-bacterial activities in vitro. Rice crop was raised from Trichoderma treated seeds and further challenge inoculates with Xoo to induce disease in plants. All the T. harzianum treated plants had lower incidence of diseases and higher yield than the untreated plant. Yield attributing characters like plant height, days of active tillering, panicle initiation and maturity, total number of grains per panicle, number of filled grains per panicle was positively influenced by Trichoderma harzianum application. However, there were variations among the treatment, isolate IRRI-5 was found most effective followed by IRRI-2, IRRI-4, IRRI-3 and IRRI-6 respectively.