MINIMUM APPLIED ETHYLENE CONCENTRATION AS IT AFFECTS SEEDLING GROWTH IN SEVERAL LEGUMES

The minimum applied ethylene concentrations which have an influence on seedling growth were made clear in six epigeal leguminous species. Th e lowest ethylene concentration which inhibited hypocotyl elongation ( LCe) significantly at 5% level ranged from 0.04 ppm (mung bean) to 0.1 6 ppm (soybean). On the other hand, the lowest concentration which inc reased hypocotyl thickness (LCt) significantly at 5% level ranged from 0.04 ppm (mung bean) to 0.38 ppm (soybean). The response of seedling growth to ethylene seemed to be classified into 3 types: 1) LCt was lo wer than LCe in kidney bear, and hyacinth bean, 2) LCt was similar to LCe in mung bean, black gram and cowpea, and 3) LCt was higher than LC e in soybean. Neither LCe nor LCt correlated with seed weight or hypoc otyl thickness, However, each LCe and LCt correlated positively with t he endogenous ethylene production of a seedling (r=0.841 and 0.869, n= 9, P<0.01). The results suggested that, in the seedlings, the high end ogenous ethylene production may be discourage the response to applied ethylene.