Comparative efficacy of fungicide and gamma radiation for controlling blast of wheat

Abstract

This research is conducted for comparison of an eco-friendly gamma radiation method and chemical fungicidal spray in reducing wheat blast incidence and severity in BINA under both artificial and natural conditions during 2019-2022. Wheat blast infection occurred on the leaves, spikes and newly emerged heads contained typical eye shaped blast symptoms. Magnaporthe oryzae Triticum (MoT), a causal agent of wheat blast was isolated by tissue panting method, cultured on OAT medium at 30 ±10C, confirmed by PCR amplified with universal MoT3 primer pairs that resulted 361 bp. The MoT inoculated (@ 5x106 CFU/mL) wheat plants successfully developed blast symptoms after 16 days in four tested wheat varieties/germplasm. An in vitro evaluation of five chemical fungicides was done against MoT where Nativo and Filia completely inhibited (100%) its radial mycelial growth. A total three spray, combination of half doses of Nativo + Filia [(0.3g + 1mL)/L] at 10 days intervals starting from one week of pre-heading or critical stage significantly reduced wheat blast incidence and severity in both artificially inoculated and natural conditions. Gamma radiated M3 population of wheat vars. also showed better performance in reduction of blast severity. Among the four doses of gamma radiation, 300 Gy significantly showed the better performance in reducing blast disease incidence and severity on wheat var. BG 26. Although combined fungicidal spray treatment (TF) significantly reduced 93.1% DI and 94.3 % DS in var. BG26 over control, but the highest percent reduction of wheat blast incidence (97.7%) and severity (98.4%) was observed on gamma irradiated (300 Gy) M3 line (BG26M3L4) under natural condition indicating gamma radiation brought a change in the genetic level positive for developing source of resistance against wheat blast. Moreover, gamma irradiated M3 line BG26M3L4 increased higher vegetative traits / yield than the combined fungicidal spray indicating gamma radiation might be a good replacement of chemical fungicides for management of blast of wheat.