Pee Dee Research and Education Center, Route 1, Box 531, 29501, Florence, South Carolina, USA.
Photosynth Res. 1990 Jul;25(1):49-57. doi: 10.1007/BF00051735.
Soybean [Glycine max (L.) Merr. cv. Williams 82 and A3127] plants were grown in the field under long-term soil moisture deficit and irrigation to determine the effects of severe drought stress on the photosynthetic capacity of soybean leaves. Afternoon leaf water potentials, stomatal conductances, intercellular CO2 concentrations and CO2-assimilation rates for the two soil moisture treatments were compared during the pod elongation and seed enlargement stages of crop development. Leaf CO2-assimilation rates were measured with either ambient (340 μl CO2 l(-1)) or CO2-enriched (1800 μl CO2 l(-1)) air. Although seed yield and leaf area per plant were decreased an average of 48 and 31%, respectively, as a result of drought stress, leaf water potentials were reduced only an average of 0.27 MPa during the sampling period. Afternoon leaf CO2-assimilation rates measured with ambient air were decreased an average of 56 and 49% by soil moisture deficit for Williams 82 and A3127, respectively. The reductions in leaf photosynthesis of both cultivars were associated with similar decreases in leaf stomatal conductance and with small increases in leaf intercellular CO2 concentration. When the CO2-enriched air was used, similar afternoon leaf CO2-assimilation rates were found between the soil moisture treatments at each stage of crop development. These results suggest that photosynthetic capacity of soybean leaves is not reduced by severe soil moisture deficit when a stress develops gradually under field conditions.
大豆[ Glycine max (L.) Merr. cv. Williams 82 和 A3127]植株在田间长期受到土壤水分亏缺和灌溉的影响，以确定严重干旱胁迫对大豆叶片光合作用能力的影响。在作物发育的豆荚伸长和种子增大阶段，比较了两种土壤水分处理下下午叶片水势、气孔导度、胞间 CO2 浓度和 CO2 同化率。用环境（340 μl CO2 l(-1)) 或 CO2 富集（1800 μl CO2 l(-1)) 空气测量叶片 CO2 同化率。尽管由于干旱胁迫，种子产量和植株叶片面积分别平均减少了 48%和 31%，但在采样期间叶片水势仅平均降低了 0.27 MPa。用环境空气测量的下午叶片 CO2 同化率，由于土壤水分亏缺，Williams 82 和 A3127 分别平均降低了 56%和 49%。两种品种叶片光合作用的减少与叶片气孔导度的相似减少以及叶片胞间 CO2 浓度的微小增加有关。当使用 CO2 富集空气时，在作物发育的每个阶段，在两种土壤水分处理之间发现了类似的下午叶片 CO2 同化率。这些结果表明，当在田间条件下逐渐发展胁迫时，大豆叶片的光合作用能力不会因严重的土壤水分亏缺而降低。
