水稲における根群の形態形成について, とくに窒素施用量を変更した場合の一例

抄録

The present study is an attempt to clarify the relation between the root system formation of rice plants and levels of nitrogen supply in paddy fields. The test material, the rice cultivar 'Mubo-Aikoku', was grown under different levels of nitrogen supply: N-nonsupply, N-8 kg level, N-16 kg level, and N-24 kg level; all levels are expressed in kilograms per ten ares. The results of observation on the root system in the longitudinal plane of the paddy were as follows: The soil depths of crown root distribution at N-nonsupply and N-8 kg level were 60 cm and 50 cm, and the depths at N-16 kg level and N-24 kg level were 40 cm and 35 cm. The fresh and dry weight of the roots grown at N-nonsupply was lighter than the others, and the weight of the roots grown at N-16 kg level was heavier than the others. The above facts seem to suggest that the shape of the root system is larger in depth and width in paddy fields with a low level of nitrogen supply and is smaller in one with a high level of nitrogen supply.