Abstract
For breeding rice with a high root-lodging resistance, which is important for direct seeding in subnerged paddy fields, selection of cultivars at the seedling stage is preferable. Twenty typical Indica and Japonica rice varieties were tested for root-lodging resistance and breaking resistance of the basal stem. Breaking resistance at the basal part of the seedling in the 20 varieties was measured using a push pull gauge at 23 days after sowing. It varied from 12.9 N to 27.9 N and lodging resistance highly correlated with the breaking resistance. Next, we selected eight varieties and examined the change in pushing resistance and breaking resistance of basal stem after heading. None of the varieties showed any significant change pushing resistance. Breaking resistance was significantly reduced in three varieties, but it did not change in five varieties. Pushing resistance at any time after heading was highly correlated with breaking resistance of the basal stem in eight varieties. Thus, it is concluded that the lodging resistance at the ripening stage of the rice varieties can be evaluated by the breaking resistance at the basal part of the seedlings.
