Quantification of resistance among basmati rice genotypes to neck blast, Pyricularia oryzae Cavara

Abstract

Level of resistance to neck blast disease (Pyricularia oryzae) was assessed in 69 rice germplasm lines including susceptible checks (Pusa 1401 and Pusa Basmati 1121) and resistant check (Tetep) under both artificial inoculation and natural epiphytotic conditions. Based on susceptibility index (Sx) value, the level of resistance among the genotypes was classified into moderately resistant (MR), moderately susceptible (MS), susceptible (S) and highly susceptible (HS) categories in comparison with controls. Sx differed significantly among test genotypes ranging from 2.83 to 12.83. Four genotypes viz., Pusa Basmati 1637, INGR 15001, INGR 15002 and Tetep exhibited a moderate level of resistance with Sx value less than 3, AUDPC value between 70-140, lesion length between 2-5mm, respectively. Only one entry RYT 3672 showed a moderately susceptible reaction to the disease having Sx value of 5.98, AUDPC value of 169.8 and lesion length of 8.34 mm. AUDPC was positively correlated with lesion length. None of the test entry showed complete resistance to the disease. These entries can be used as donors for strengthening neck blast breeding programme in rice.