Influences of Spacing (especially denser spacing) on the Growth and Function of Root of Paddy Rice Plant Sown Directly

[摘要] 1. The experiment was carried on the spacing (square of 50, 25, 12.5, 6.25 cm, respectively) combined with or without the restriction of root area (alike to the surface area and its 1/4, 1/16, 1/64) using bottomless frame-work (20cm depth) board plastic materials. The aim of experiment was to clarify the reaction of the plant to the restriction of growing sphere, and special emphasis was laid on the growth and function of root. Results obtained were as follows: 2. Under the condition of denser spacing, the plant increased in number of primary roots per stem, on the other hand, decreased in their weight per unit number. The rot system was distributed shallowly under those conditions. 3. The activity of root, in terms of the capacity to oxidize α-naphthylamine, was depressed either by denser spacing or by stronger restriction of root area. 4. The oxidation-reduction potential of soil in root area was also lowered by denser spacing. 5. The content of mineral nutrients in rice plant was decreased by denser spacing or stronger restriction of root area, especially, that of potassium in either top or root was remarkably decreased by these conditions at later stage of growth. 6. Root of rice plant grown under denser spacing is characterized to distribute shallowly and to be easily depressed in the activity through the deterioration of circumstantial conditions.

[学科分类] 农业科学（综合）