EVALUATION OF WHEAT GENOTYPES FOR SPOT BLOTCH (Bipolaris sorokiniana Sacc.) RESISTANCE AT KHAIRAHANI, CHITWAN

Abstract

Wheat (Triticum aestivum L.) is the third most important cereal crop of Nepal in terms of area and production. Spot blotch caused by Bipolaris sorokiniana Sacc. is one of the major diseases reducing the productivity and quality of wheat in Nepal, which is favored by high temperature and relative humidity. The experiment was conducted at research farm of Rampur Campus, Khairahani, Chitwan from 18th Nov 2021 to 29th Mar 2022, to identify the genotypes resistance against spot blotch. It was laid out in Randomized complete block design (RCBD) with twelve genotypes as treatments and three replications. Double digit scoring method was used to assess the disease five times from 90 DAS at the interval of 7 days and Area under disease progress curve (AUDPC) was calculated. Statistically, significant difference was obtained in all the observed traits except for plant height, spike weight, harvest index, and straw yield. The highest AUDPC value was recorded in RR-21 (2074) yielding 4.0 tonha-1 whereas the lowest AUDPC value was recorded in NL 1437 (781) yielding 6.1 tonha-1, suggesting it to be more resistant than other genotypes. NL 1447 was the highest yielder (6.5tonha-1) with a 985.185 mean AUDPC value followed by NL1437 (6.1 tonha-1) while RR-21 was the lowest yielder (4.0 tonha-1). The lowest apparent infection rate was detected for BL 4951 (0.018). Correlation studies indicated that total grains and grain weight per spike as well as the grain yield were negatively and significantly correlated with AUDPC.