Assessment and impact of spot blotch resistance on grain discolouration in wheat

Abstract

Ninety four numbers of released varieties and genotypes of wheat and Triticale were evaluated against spot blotch caused by Bipolaris sorokiniana to assess the their levels of resistance under artificially inoculated conditions as well as to see the impact of resistance on grain colour. The seeds were analyzed for the presence of discolouration and black point after harvest. Based on spot blotch score, the genotypes were categorized in to resistant (R), moderately resistant (MR), moderately susceptible (MS) and susceptible (S) categories. The per cent black point and discoloured seeds were counted in one hundred seed sample per genotype. A total numbers of 43, 16, 18 and 17 genotypes were in the category of R, MR, MS and S, respectively against spot blotch. The most promising released varieties and genotypes showing high per cent of healthy looking seeds (99.5% or more) were, HS 375, K 65, Milan/Sha-7, NI 5439, VL 616, VL 804, VL 907, and genotype UP 2691 in T. aestivum (bread wheat), HI 8627 in durum wheat variety, and Triticale variety, TL 2942 and were in first significant group. Amongst different varieties and genotypes having significantly high total diseased seeds, were 7.0, 18.8, 27.8 and 58.8%, in case of R, MR, MS and S categories, respectively (Fig. 1). In statistical terms, the range of entries showing significantly high per cent discoloured, black point and total infected seeds were, 0.0-14.4, 2.3-18.8 and 7.0-18.8% respectively in R-MR types of varieties and genotypes, which was much lower than MS-S types showing 16.7.1-52.9, 16.7-47.1 and 27.8-58.8%, respectively.