Abstract
The relationships between morphological characteristics and ripening ability of rice were investigated with Chinese varieties, Japanese varieties and high-yielding varieties bred in Asian countries. Multiple regression analysis was performed to examine whether the ripening ability of rice can be estimated by morphological characteristics. The results demonstrated that the percentage of ripened grains (R) was closely related to some characteristics associated with yield capacity and structure of spike. Specific gravity of winnowed rough rice (S) showed close correlations with characteristics associated with dry matter production. Morphological characteristics, e. g., number of grains per head (X1), length of neck internode (X2), ear number (X3), diameter of neck internode (X4), and, angle of flag leaf (X5) were selected as explanatory variables. Multiple correlation coefficients of the analysis with R as the dependent variable and X1 and X2 as explanatory variables, and S as the dependent variable and X3, X4 and X5 as explanatory variables were both significant. Thus, the results demonstrated that the varietal differences of ripening ability could be explained about 30—35% by morphological characteristics. These results suggest that morphological characteristics used as explanatory variables in this study may be useful as the selection index of ripening ability at the early ripening stage of rice.
