Studies on the Index of Drought- Resistance in Some Rice Varieties

Eighteen varieties (or combinations) of typical Japonica-type and hybrid rice were grown in paddy and rainfed cultivations, physiological and economical drought resistance and the relationship between drought-resistance indices and the yield were discussed. In this report, two physiological indices at different growth stages were closely related to ther yield under water stress. Percentage of seed setting in dryland was the most direct index of drought-resistance of rice. K-value grading as a basis for rice resistance to drought was also evaluated.