Abstract
Patterns of starch accumulation and ethylene evolution during the course of regrowth in different types of alfalfa, cultivars from tropical and temperate areas, were examined. Results were discussed in relation to the differences between cultivars and seasonal changes. 1. No changes were detected in plant hight in varieties of extremely non-hardy, non-hardy and intermediate type, however in the extremely hardy type, the plant height was less than the others (Fig. 2). 2. Stem number of the tropical and the extremely hardy types were larger than those of the others, and the former showed rapid increase but the latter did not (Fig. 3). 3. After cutting, regrowth in the top took precedence to that in the root, and when there were not enough assimilation products, starch was retranslocated from the root to the top. So starch accumulation in the root arose from surplus assimilation products ln the top. The differences in starch accumulation in the root might be brought about by differences in the top (Figs. 4, 6). 4. The decrease in starch accumulation in the root was brought about mainly by growth in the top ; when growth in the top was high in activity, the changes in starch accumulation were less (Figs. 5, 7). 5. The cause of the differences in ethylene evolution was thought to arise from differences in growth activity. These differences may be mainly caused by aging of plants at the beginning of the flowering stage. Ethylene evolution rates changed at each growth stage. After flowering, ethylene evolution was decreased (Figs. 8, 9). 6. Starch accumulation and ethylene evolution during the regrowth period accompanied with each other ; therefore, ethylene may promote the increase and decrease of starch accumulation. So, in the future, it is necessary to clarify the relationship between starch accumulation and ethylene evolution.
