Submergence Tolerance of Transplanted Rice Seedlings with Several Plant Ages in Leaf Number : Relationship between the growth during submergence and survival

[摘要] The adverse effect of elongation growth and the beneficial effect of carbohydrate supply on tolerance to complete submergence for 10 days were evaluated in five kinds of transplanted rice seedlings, with plant ages of 2.0, 2.3, 2.5, 2.7, and 3.4 in leaf number in 1993 and 1994. The percent survival of seedlings with a plant age of 3.4 was lowest, and seedlings with a plant age of 2.5 showed the highest level of submergence tolerance among the seedlings in both years. The percent survival of seedlings positively correlated (r=0.951*) with the increase in shoot dry weight during submergence. In contrast, a negative correlation berween elongation growth (% of nonsubmerged seedlings) and percent survival was observed in each year. When the length of leaf sheath was longer than that of the leaf blade under submergence, the percent survival decreased and the percent survival in both years was reflected by a regression line (r=0.757*). Furthermore, a strong positive correlation (r=0.998***) was found between the ratio of increase in shoot dry weight to length of leaf sheath at the end of submergence and the percent survival. These findings suggest that the difference in submedrgence tolerance among seedlings is due to the difference of elongation growth, depending on the developmental stage of a leaf and the supplied carbohydrates to the growth zone of elongating leaves.

[学科分类] 农业科学（综合）

[关键词] Carbohydrate;移植;Elongation;イネ;Plant age in leaf number;冠水;Rice;伸長;Seedling;炭水化物;Submergence;è‹—;Transplanting;葉齢