1988 Volume 57 Issue 4 Pages 621-626
This investigation was conducted to clarify varietal differences of the ratio of stem weight to root weight (RSR) and to explain the relationship between RSR and some other characteristics by measuring dry matter weight of the stem and the root of a number of soybean cultivars. Due to the environmental factors during the growing season, stem weight and root weight varied greatly; in contrast RSR was rather stable. It was therefore, concluded that RSR is more stable than stem weight and root weight (Table 2, 3). The highest RSR measured was more than twice as large as the lowest RSR and marked varietal differences were recognized in the RSR (Table 1, 2, 5). A significant positive correlation was recognized between RSR and the length of growing period and also between RSR and seed yield, but except the effect of the length of growing period, no significant positive correlation was found between RSR and seed yield in early cultivars (Table 4, 5). It was also recognized that the stem weight and root weight of many new cultivars became greater year by year, but the increase of stem weight was less than that of root weight. Thus, RSR is gradually decreasing each year (Fig. 2, Table 6). In order to obtain higher seed yield, it is very important to develop a breeding method or cultivation method by which stem diameter and branching are increased.
