Studies on the Varietal Difference in the Characters of High-yielding Rice.

Abstract

The relationships between the early growth after transplanting and several seedling characteristics of 10 high-yielding varieties bred in Asian countries(H group)were compared with those of 10 Japanese varieties(J group). There were sighnificant differences between the seedlings of the two groups in plant length, root dry weight and the percentage of endosperm consumption. Plant length was shorter, root dry weight was heavier and the percentage of endosperm consumption was higher in the H group than in the J group. The seedling character index(SCI)shown by(the seedling age in leaf number)×(the ratio of top dry matter weight to plant length)of the H group was higher than that of the J group. The relationship between the number of days affer sowing(X)and the leaf number of seedling(Y1)was shown by Y1=a1+b1X and the relationship between X and the percentage of endosperm consumption(Y2)by Y2=100-a2·exp(-b2X). There was no significant difference between the H and J groups in the constant b1(leaf number increase coefficient, LNG), but the constant b2(endosperm consumption coefficient, ECC) of the H group was significantly higher than that of the J group. SCI was positively correlated with LNC and ECC. Top dry matter weight(TW)and leaf area(LA)at 28 days after transplanting were greater in the H group than in the J group. Significant positive corrlations were found between SCI and TW, LA, From these results, it was considered that the high yielding varieties with higher SCI have large LA and superior early growth affer transplanting.