Studies on Internode Elongation in Soybean Plants : I. Internode elongation patterns of the main stem in four late soybean cultivars

[摘要] Control of internode elongation is important to avoid seed yield reduction caused by the lodging and competition for photosynthate between stem and pods after flowering in soybean (Glycine max Merr.). The internode elongation of the main stem was continuously observed with pot-grown plants of four late soybean cultivars, Fukuyutaka, Himedaizu, Tanbaguro and Akiyoshi. Consideration was also taken on the relationship between the internode elongation and development stage of the main stem expressed by the number of emerged leaves (≥8mm long) on the main stem (1=cotyledon, 2=primary leaves, 3=the first trifoliolate leaf……, N=(N-2)th trifoliolate leaf). Elongation of internodes on the main stem began slowly at the early phase, followed by rapid rate during the mid-phase and again slowed down at the cease phase. This elongation speed pattern is similar to that of the main stem growth. Final length of the first internode between cotyledonary and primary nodes was the longest, while the 3rd or 4th internode was the shortest among all the internodes. Those of the internodes above the shortest one became longer gradually, but uppermost two or three internodes reduced their length again. When the development stage of the main stem reached the N leaves, the (N-2) th internode elongated the most rapidly, while the (N-4) th internode stopped its elongation. The similar pattern of internode elongation and synchronization were observed in all cultivars used. These results will be helpful information in controling soybean internode elongation.

[学科分类] 农业科学（综合）

[关键词] Elongation pattern;出葉;Internode;伸長経過;Internode elongation;節間;Leaf emergence;節間伸長;Soybean;ダイズ;Synchronism;同伸性;Synchronization in elongation;同調性