INTERNODE ELONGATION CHARACTERISTICS OF I NDETERMINATE TYPE PLANTS OFSOYBEAN

The purpose of this study was to clarify the internode elongation patt ern and growth habits of indeterminate type cultivars of soybean. Inte rnode elongation of the main stem was continuously observed for indete rminate type cultivars. Indeterminate type cultivars continued to elon gate their stems for about one month after the beginning of flowering, while determinate ones stopped their elongation after 10 days. So, in determinate type cultivars had much more internodes and the main stems were longer than those of determinate cultivars. Elongation of intern odes on the main stems of indeterminate type cultivars began slowly at the early phase, followed by a rapid elongation during the mid-phase and again slowing down in the final phase. The final length of the fir st internode between the cotyledonary and primary nodes was rather lon g, while the 3rd internode was very short. Those of the internodes abo ve the 3rd one became longer gradually, but some of the uppermost inte rnodes were shorter in length. When the Nth leaf on the main stem bega n emerging, the (N-2) th internode elongated most rapidly, while the ( N-4) th internode stopped elongation in indeterminate type cultivars. These patterns of internode elongation and synchronization were the sa me as those of determinate cultivars. This seems useful to control pla nt type in soybean.