Excess moisture injury of buckwheat (Fagopylum esculentum Moench) cultivated in a drained paddy field

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Upland crops grown in a drained paddy field are apt to be damaged by excess moisture. Recently, in Japan 80% of buckwheat (Fagopylum esculentum Moench) are cultivated in a drained paddy field. The purpose of this study is to investigate whether there is varietal difference for excess moisture resistance in buckwheat, to clarify the mechanism of excess moisture injury and to find out some countermeasures for it.1. Test for excess moisture resistanceForty-six cultivars (lines) of common buckwheat and two lines of tartary buckwheat (Fagopylum tataricum Gaertn.) were tested for excess moisture resistance. It was observed that there was varietal difference in excess moisture resistance in buckwheat seedlings. Difference in excess moisture resistance was attributed to the difference in leaf area and photosynthetic rate per unit leaf area Simple test on excess moisture resistance was also possible only by the measurement of the plant length.2. Countermeasure against excess moisture injuryBuckwheat (cv. Kitawasesoba) was grown in a drained paddy field and flooding treatment was made at the flower-bud differentiation stage. For reducing excess moisture injury, ridging before sowing or molding before flooding treatment was done. The photosynthetic rate, bleeding, leaf nitrogen content and seed yield were decreased by the flooding treatment. However, these decrease in either rigging or molding plots were lower than those in non-ridging or non- molding plots.As a result, it was found that ridging before sowing and molding before encountering the excess moisture were proved to be effective for reducing excess moisture injury in a drained paddy field.