Studies on the Emergence of Rice Seedlings in the Direct-Sowing Culture. : 3. Strength of elongation of coleoptile and foliage leaves of rice plants.

Abstract

Recently direct-sowing culture of paddy rice has been put into practice and it has given rise to a problem in seedling-emergence. This experiment was made on the strength of elongation of coleoptile using strain meter. The measurement of the strength was made in darkness at 30°C. In this experiment about 15-30 mm length of coleoptile was used as material. In some cases, strength of elongation of foliage leaves was measured. Results were as follows: 1. Strength of elongation of coleoptile of paddy rice plants decreased with the increase of soil moisture content. The strength of "Ariake" was about 15 g in 15 percent moisture plot, 12 g in 20 percent moisture plot and only 0.6 g in 25 percent moisture plot. The strength was more vigorous in coleoptile of well ripened seed than that of poorly ripened seed. 2. Strength of elongation of coleoptile differed in each type of rice plants, i.e., in 15 percent moisture plot, 15.9 g-11.8 g of paddy rice plants and 11.7 g-10.3 g of upland rice plants in japonica type, and 18.9 g-9.9 g of rice plants in indica type. 3. As regards the coleoptile of paddy rice plants, no positive relationship between the strength of elongation of coleoptile and the height or maturity was observed. 4. Strength of elongation of imperfect leaf was about 22 g and that of the 1st leaf was about 4 g in 15 percent moisture plot.