Department of Plant Breeding, International Rice Research Institute, P.O. Box 933 Manila, Philippines.
* Present address: 4B, Santosh Apartments, No.2 Palm Grove Road, Bangalore 560047.
Direct and indirect effects of nine traits associated with cold tolerance at an early seedling, seedling and booting stages on per cent fertility were identified in rice using path coefficient analysis. Selection for increase in tolerance index 5 days after revival tolerance, based on 15 days of survival, and number of fertile spikelets, and decrease in tolerance index 10 days after revival treatment and based on final survival would be effective in increasing fertility. Tolerance index 5 days after revival treatment and based on 15 days of survival appear useful as selection criteria. As these traits were negatively correlated with fertility, a compromise would have tobe made for simultaneous selection for cold tolerance at vegetative and reproductive stages in rice.
Rice, path-coefficient analysis, cold tolerance
