Studies on the varietal difference in the characters of high-yielding rice- Relation between character of seedling and early growth after transplanting

The relationships between the early growth after transplanting and several seedling characteristics of 10 high-yielding varieties bred in Asian countr ies (H group) were compared with those of 10 Japanese varieties (J group). There were significant differences between the seedlings of the two groups in plant length, root dry weight and the percentage of endosperm consumptio n. 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. Th e seedling character index (SCI) shown by (the seedling age in leaf number) x (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 day s after sowing (X) and the leaf number of seedling (Y-1) was shown by Y-1=a (1)+b(1)X and the relationship between X and the percentage of endosperm co nsumption (Y-2) by Y-2=100-a(2).exp (-b(2)X). There was no significant diff erence between the H and J groups in the constant b(1) (leaf number increas e coefficient, LNC), but the constant b(2) (endosperm consumption coefficie nt, 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 gro up than in the J group. Significant positive correlations were found betwee n SCI and TW, LA. From these results, it was considered that the high yield ing varieties with higher SCI have: large LA and superior early growth afte r transplanting.