Abstract

Aerobic rice cultivation is an efficient water saving strategy which maintains a significantly higher yield than traditional upland varieties. The upland rice in South East Asia is largely affected by parasitic rice root knot nematode, Meloidogyne graminicolacausing severe yield losses. In the present investigation 14 widely cultivated traditional upland varieties and 45 breeding genotypes improved for aerobic adaptation belonging to Oryza sativa species were evaluated against M. graminicola. Experiment in indoor growth chamber revealed a wide variability among and within the two rice ecotype in terms of nematode population and fresh root weight. Average of final and initial population ratio (RF value) for second stage juveniles (J2) in aerobic rice genotypes (6.5) was significantly lower than upland cultivars (87.1). O. glaberrima accessions CG 14 and TOG 5674 behaved as true resistant references (RF=1). Among traditional cultivars WAB 638-1 and IRAT 216 and among aerobic rice genotypes IR 81426-B-B-186-4 and IR81449-B-B-51-4 showed significant resistant reaction against M. graminicola. Moreover, heritability analysis showed resistance among evaluated rice genotypes is heritable. Our study concluded that newly emerged aerobic rice genotypes were superior to traditional upland cultivars in terms of resistance to rice root knot nematode and improvement of these genotypes for resistance is feasible.

Key words: Aerobic rice, traditional upland rice, Oryza sativa, Meloidogyne graminicola, heritability analysis.