Studies on Growing Behavior of Sugar Beet Plant in the Warmer Districts of Japan : II. Effect of nitrogen fertilizer on growing behavior

[摘要] In a previous part we had already reported that the whole cycle of sugar beet plant sown in summer in the warmer districts of Japan would be distinguished into four different and successive stages. However, such growing behavior would be fairly varied with environmental and cultural factors; especially, it is a wellkown fact that nutritional state is easy to effect upon the root yield and its chemical quality of sugar root root. Here, we carried out this experiment to know how nitrogen fertilizer effects to the growing behavior. The variety used was D0-nyu No. 2 sown on August 16, and three nitrogen levels were set up as seen in Table 1. The results can be summarized as follows: The growth of top part is more vigorous in order of high, intermediate, and low nitrogen levels (fig. 1, 2), but the development of storing root is hot always the more vigorous under the higher levels, i. e. there is no difference between high and intermediate (fig. 3). These results show us that too much growth of top does not contribute to development of storing root. The turning times from rapid growth stage to root ripening one are clearly retarded under higher level, and winter-kill of leaves is less, but the initial times of regrowth under three levels is nearly simultaneous, perhaps inducing by rising of air temperature over about 10°C (fig. 1, 2). Sugar content in root is pretty higher under high level than under low one, though there is no principal difference in varing trend (fig. 5). On the other hand, we could find an noticeable phenomenon about variation of sugar purity, that is, the purity under high level drops temporarily for a while after beginning of regrowth, after which it is rising again, and it is also closely associated with reverse variation of root nitrogen compositions (fig. 6). This phenomenon is probably due to accumulation of excessive nitrogen taken up out of soil into the storing roots. On the seasonal variation of reducing sugar, raffinose, ash and unsoluble solid in root there is no principal difference with nitrogen levels. From the results described above, the growing behaviors under higher and lower nitrogen levels could be illustrated schematically as shown in fig, 10.

[学科分类] 农业科学（综合）