Morphological basis of resistance in rice against yellow stem borer, Scirpophaga incertulas (Walker)

For screening of 25 rice varieties with a view evaluate their relative resistance or susceptibility on morphological basis against yellow stem borer, Scirpophaga incertulas (Walker), a field experiment was conducted at the NARP Farm, Navsari Agricultural University, Navsari during kharif 2011 and 2012. The varieties GAR 13 and IR 22 were observed showing resistant reaction, while thirteen varieties viz., Narmada, NAUR 1, GR-6, GR-7, GR 12, GR-102, GR-103, Pawna, IR 28, IR-50, IR-66, PRH 10 and PR 116 were found to be moderately resistant. The varieties GR 4, GR 10, GR-101, GR-104, Dandi, GR-5 and Gurjari were moderately susceptible, while GR 11 and GR 9 were susceptible, and significantly higher infestation was recorded in the highly susceptible variety, Jaya.

The deadheart and white earhead symptoms exhibited direct positive relationship with leaf width, flag leaf length, flag leaf area, number of leaves, and stem diameter. Such relationship was negative with plant height, flag leaf width, number of internodes and internode length. The characters viz., leaf length, leaf area, number of productive tillers, length of panicle and culm length did not show any significant relationship. Thus, the rice varieties with more plant height having narrow leaf, minimum number of leaves, wide and short flag leaf, maximum number of internodes, higher internode length and lower stem diameter could be utilized in the breeding programme for developing new high yielding yellow stem borer resistant varieties.