Photosynthetic Responses of Four Legume Crops to Fluctuations of Evaporative Demand Following the Rainy Season
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概要
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In the typical climate of East Asia, summer crops develop large shoots with relatively poor root systems during the rainy season, leading to restricted photosynthetic activity in the following summer months. The objectives of the present study were 1) to determinate if there are specific differences in the photosynthetic responses of four legume crops to daily fluctuations of evaporative demand and 2) to identify physiological attributes responsible for the differences. Soybean, azuki bean, cowpea and peanut were grown in a field, and apparent leaf photosynthetic rate (AP) and gas exchange parameters as well as water potential and transpiration rate were measured at midday on three consecutive summer days. When leaf-to-air vapor pressure deficit (VPD_<1a>) varied from 1.72 to 3.44 kPa during the experimental period, the four species responded differently. The AP of soybean and that of azuki bean decreased with increasing VPD_<1a> over a range of 1.72 to 3.44 kPa, whereas the activities of cowpea and peanut were greatest at VPD_<1a> around 2.53 kPa. The leaf water potentials of soybean, azuki bean and cowpea reached minima at VPD_<1a> around 2.53 kPa, while that of peanut was fairly constant over the VPD_<1a> range of 1.72 to 3.44 kPa. The transpiration rates of soybean, azuki bean and cowpea were greatest at VPD_<1a> around 2.53 kPa and decreased beyond that range of VPD_<1a>, while peanut transpired actively with increasing VPD_<1a>. AP of soybean was correlated with leaf water potential, whereas that of cowpea and peanut was correlated with transpiration rate. With respect to water relation, peanut was most tolerant to increasing VPD_<1a> among the four species tested, presumably because it maintained higher water potential and transpiration rate than the other species under the condition of high VPD_<1a>.
- 東北大学の論文
- 2004-03-25
著者
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Kokubun Makie
Laboratory Of Crop Science Graduate School Of Agricultural Science Tohoku University
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Matsunami Toshinori
Laboratory Of Crop Science Graduate School Of Agricultural Science Tohoku University