Studies on the varietal difference in the characters of high-yielding rice - Varietal difference in bleeding rate

The varietal difference in bleeding rate was investigated using 10 Japanese varieties (J group) and 10 high-yielding varieties of rice bred in Asian countries (H group). The relationship between bleeding rate and yield characters was examined. Bleeding rate at the heading time (BR1) and maturing time (BR2) ranged from 2.20 to 3.92, and from 1.50 to 2.62 (g h(-1) hill(-1)), respectively. There were no significant differences in BR1 and BR2 between the two groups. The reduction rate of bleeding rate (RRB) during the ripening period shown by 1-BR2/BR1 was significantly higher in the W group than in the J group. BR1 was not significantly correlated with the number of the phytomers (TPN), but showed a significant positive correlation with BR1/TPN. BR1 also showed a significant positive correItion with the shoot dry weight at the heading lime. There was a significant positive correlation between RRB and the decline of leaf color (DLC) during the ripening period. Moreover, a significant negative correlation was found between RRB and the percentage of ripened grain. These results imply that the variety with a higher RRB and DLC has a lower ripening ability.