三平, 東作

野島, 博

MIHIRA, Tosaku

NOJIMA, Hiroshi

TAKASAKI, Yasuo

Drought after seeding in forage crops is considered to bring poor stand probably resulted from the inhibition of the germination and the early growth of seedling. However, the effects of drought in germinating seeds have been studied little. The authors (1979) suggested that the germination and the early seedling growth of grass are greatly affected by the period and duration of the drought. The object of the present experiment was to clarify the effect of water stress in germinating seeds of 7 legume species; soybeans, vetch, milk vetch, alfalfa, red clover, alsike clover and white clover. The seeds were placed on moist paper upon glass small tubes in a Petrie dish and kept in a germinator at 30℃. After 6, 18 or 30 hours of incubation, the seeds were transferred to a desiccator controlled at 40-50 percent relative humidity, then dried for 3 or 6 days. After this temporary water stress, seeds were grown in the germinator for 5 days. The species tested were grouped into three types according to the degree of the tolerance to the temporary water stress: the first group, alfalfa and red clover, is easily injured by the water stress; the second one, alsike clover and white clover, is moderately damaged and the third one, soybean, vetch and milk vetch, is highly tolerant to the water stress. Seeds were more susceptible in the advanced stage than in the early stage of germination. The temporary water stress in the third type species, soybean, vetch and milk vetch, increased the germination percent and promoted subsequent growth of seedlings probably owing to breaking the dormancy.