Inheritance studies on spot blotch of wheat caused by Bipolaris sorokiniana

Abstract

Spot blotch of wheat caused by Bipolaris sorokiniana (Sacc.) Shoem, is one of the most important disease constraints to wheat cultivation in the north-eastern and eastern plain zones of India. Genetics of resistance to spot blotch was studied in seven resistant wheat lines viz., Chirya-3, Mayoor, Shanghai-4, Suzhoe 128-OY, Suzhoe 1- 58, Longmai and Chuanmai #18, by crossing them with two susceptible varieties Sonalika and HD-2329. Studies under both artificial inoculation and natural epiphytic condition in F1, F2 and backcross generations indicated that resistance in Chirya-3 and Mayoor is governed by two dominant genes. The test of allelism showed that the resistance genes in the Chirya-3 and Mayoor are allelic. The continuous nature of frequency distribution for AUDPC of spot blotch reaction in F2 generation involving resistant parents of Chinese origin did not suggest any simple Mendelian inheritance. The type of resistance among the resistant parents of Chinese origin Shanghai- 4, Suzhoe 128-OY, Suzhoe 1-58, Longmai and Chuanmai #18 appears to be additive with polygenic control as the F2 populations of the susceptible x resistant crosses exhibited different degrees of disease reaction of all categories, viz., resistant, moderately resistant, susceptible and highly susceptible.