Studies on ripening of rice varieties grown under low temperature. IV. Application of principal component analysis on some ripening characters.

Abstract

Thc ripening ability among 39 varieties was compared in order to select the breeding materials for raising new variety which has superior ripening ability. An ideotype for ripening ability was also investigated by using the principal component analyais. 1. The remarkable varietal differencies for ripening ability were found. 「Kitaake」, 「Kitahikari」, 「Kitakogane」and「Narukaze」will be useful as the mother plants for raising new superior ripening variety. 2. From the results of the principal component analysis, in the case of the first principal component, the dry matter production after the heading time was positively contributing, and the culm length, the plant type index and the dry weight at the heading time were negatively contributing to the principal component. In the case of the second principal component, the length fom flag leaf auricle to the neck node of panicle was positively contributing, and the percentage of primary rachis branch grains to total grains per head, flag leaf angle from the horizontal line and the ratoon weight were negatively contributing to the principal component. 3. There was a negative significant correlation (r=-0.70*** between the ripeneng ability at the early stage of ripening and the second principal component. The ripening ability at the late stage indicated positive significant correlation (r=0.69*** with the first principal component. These results suggest that the variety having both large first principal component and small second principal component is an ideotype for ripening.