Effect of Water Supply and Defoliation on Photosynthesis, Transpiration and Yield of Soybean

Japanese Journal of Crop Science

Shigeo MATSUI¹  Shinji SHIMADA¹  Hideaki SHIBATA¹  Makie KOKUBUN¹ 

关键词: Defoliation;    気孔コンダクタンス;    Glycine max;    光合成速度;    Leaf water potential;    蒸散;    Photosynthesis;    ダイズ;    Stomatal conductance;    摘葉処理;    Transpiration;    水ストレス;    Water stress;    水ポテンシャル;   

DOI  :  10.1626/jcs.61.264

学科分类：农业科学（综合）

来源: Nihon Sakumotsu Gakkai / Crop Science Society of Japan

【 摘 要 】

While increasing leaf area increases CO2-fixing ability of plants, it also increases transpiration and may cause water deficit within a plant. This study was conducted in order to analyze the combined effects of leaf area and water-supply treatments on photosynthesis, water status, and yield of pot-grown soybeans (Glycine max [L.] Merr. cv. Tachinagaha). When plants reached the R4-R5 stage, the leaf area of a whole plant was altered by defoliating one, both; or none of the lateral leaflets of each trifoliate, and three levels of water-supply treatments (2100, 1000, 500 ml/day) were given until maturity. Transpiration per plant (Tr/P) was approximately equal to water supply regardless of leaf area under water-restricted conditions (1000, 500 ml/day). With sufficient water supply (2100 ml/day), Tr/P varied with leaf area. Across all the treatments, there was a clear linear relationship (r =0.994**) between apparent photosynthetic rate (AP) and stomatal conductance (gs) at one week after the initiation of water-supply treatment. Increasing water supply increased gs and AP. In water-restricted plants, decreasing leaf area by defoliation raised leaf water potential and caused higher gs and AP of the remaining leaves. Successive water stress of water-restricted plants decreased leaf chlorophyll content and AP at the late ripening stage. Grain yield was reduced by defoliation only under well-watered conditions but was not affected by defoliation in water-restricted plants. The data suggest that water supply proportionate to leaf area is essential to maximizing soybean yield.

【 授权许可】

Unknown