Abstract
Pot experiments were conducted to observe the effects of incorporation timing and the amount of Chinese milk vetch (Astragalus sinicus L.) on the flowering and ripening of summer buckwheat (Fagopylum esculentum Moench, cv. Kitawasesoba). Chinese milk vetch as green manure was incorporated into the soil at rates of 50 g, 100 g, 200 g and 300 g fresh weight per pot of 5 liters in 1999, and at 50 g, 150 g and 300 g per pot in 2000. Early incorporation of larger amounts of Chinese milk vetch resulted in a higher seed yield in both years. A higher seed yield was obtained due to a larger number of flowers per plant. This early incorporation also increased the inorganic nitrogen content of the soil, promoting plant growth, and increasing the number of flowers. In addition, in spite of the greater number of flowers, the seed-setting rate did not decrease, possibly due to the high photosynthetic rate per plant brought by increase of leaf area during the middle ripening period. It is assumed that a sufficient amount of photosynthate was supplied to each flower under such conditions. It can be concluded that the early incorporation of 300g Chinese milk vetch into 5L pot was the best for the cultivation of summer buckwheat.
