2019 Volume 88 Issue 4 Pages 268-272
In order to obtain fundamental information on petiole elongation for improving soybean plant type, the petiole elongation on the main stem was continuously observed in detail using pot-grown plants. The determinate growth type Fukuyutaka was used in this experiment. The elongation of petiole on the main stem was slow at the early phase, rapid during the mid-phase and again at the late phase. Concerning the final length of petiole on the main stem, the first trifoliolate leaf was the shortest and longer at upper position, while uppermost 2nd or 3rd petiole was the longest of the petioles. This pattern was similar to the final internode length on the main stem. A positive correlation was found between the Nth petiole length and the (N-1)th internode length in the same phytomer. This relationship suggests that the effects of various factors on the petioles would be similar to those on the internodes. When the Nth leaf emerged, the (N-2)th petiole elongated the most rapidly, the (N-6)th or (N-5)th petiole stopped elongation. The late phase of petiole elongation was considered to be more susceptible to the effects of environmental stress than that of internode elongation. These results would be useful for controlling soybean petiole elongation to improve the plant type.
