Studies on the Late Season Culture of Paddy Rice in Hokuriku District. : II. The unusual elongation of leaf-sheath in the late season culture of paddy rice.

摘要

It is a troublesome problems that the seedlings are very soft and show remarkable withering when transplanted in the late season culture of paddy rice. Besides, these seedlings have a low "dry weight/plant height" ratio and are low in the dry matter percentage as reported in the previous paper. The authers found in this study that they were characterized by the over-growth, especially by the unusual elongation and the low dry matter content in the leaf-sheath. The lowland seedlings compared with the upland seedlings, as a rule, show more severe withering and in addition over-growth of the leaf-sheath, the dry matter content of its leaf-sheath being lower than that of the upland seedlings. These phenomena are considered to be the cause of the withering. The relation between the over-growth of leaf-sheath and the withering can be attributable to the following points; firstly the decrease in the latent recovering capacity from withering owing to decreased nutrition amount in leaf-sheath caused by over-growth, secondly lowered physical resistance to withering and finally the disturbance of water balance in seedlings, because the tall seedlings resulted in the greater aerial parts of plant, above water surface in the paddy field.