Physio-Ecological Characteristics in Roots of Rice Plants Grown under Different Soil Temperature Conditions : (1) Their ecological characteristics

[摘要] Rice plants (var. Norin No. 29), of which roots were treated in water tanks kept at 33°, 28°and 23°C constantly, were grown from July to September 1960. During the course of the growth, they were sampled three times to examine ecological characteristics of their roots. Main results obtained were as follows: (1) In view of values such as R/T and k=log R/logT (Fig. 3, 4), the growth of roots was always larger in contrast to that of top throughout the whole growth, when plants were placed under lower temperature conditions. In the 28°C plot (medium temperature), the growths of top and roots were in the most balanced proportion among plots examined. Moreover in that plot, the largest growth of top were recognized (Fig.1). (2) The higher the temperature, the larger in number of primary roots per plant and tiller (Fig. 5, 6) and the shorter the length of primary roots (Fig. 10). Root diameter was however independent upon conditions, but was somewhat larger in lower temperatures (Fig. 12). In the 28°C plot, lateral roots emerged from primaries were in the largest number (Fig. 7, 8). In consequence the largest of the total number, total length and total surface area of roots per plant were estimated in that plot (Fig. 9, 11, 13). These results reflected to the largest dry weight of top in that plot. Roots under lower temperature conditions appeared to be less aged, because they had less iron coatings and more fresh appearance than those treated by higher temperatures. Dry weight per unit volume of roots suggested these phenomena mentioned above (Fig. 14).

[学科分类] 农业科学（综合）