Weisz P R, Denison R F, Sinclair T R
Agronomy Department, University of Florida, Gainesville, Florida 32611.
Plant Physiol. 1985 Jul;78(3):525-30. doi: 10.1104/pp.78.3.525.
The effects of drought stress on soybean nodule conductance and the maximum rate of acetylene reduction were studied with in situ experiments performed during two seasons and under differing field conditions. In both years drought resulted in decreased nodule conductances which could be detected as early as three days after water was withheld. The maximum rate of acetylene reduction was also decreased by drought and was highly correlated with nodule conductance (r = 0.95). Since nodule conductance is equal to the nodule surface area times the permeability, the relationship of these variables to both whole-plant and unit-nodule nitrogenase activity was explored. Drought stress resulted in a decrease in nodule gas permeability followed by decreases in nodule surface area when drought was prolonged. Under all conditions studied acetylene reduction on a unit-nodule surface area basis was highly correlated with nodule gas permeability (r = 0.92). A short-term oxygen enrichment study demonstrated nodule gas permeability may limit oxygen flux into both drought-stressed and well-watered nodules of these field-grown soybeans.
通过在两个季节和不同田间条件下进行的原位实验，研究了干旱胁迫对大豆根瘤导度和乙炔还原最大速率的影响。在这两年中，干旱均导致根瘤导度降低，早在停水三天后就可检测到。干旱还降低了乙炔还原最大速率，且与根瘤导度高度相关（r = 0.95）。由于根瘤导度等于根瘤表面积乘以渗透率，因此探讨了这些变量与整株植物和单位根瘤固氮酶活性的关系。干旱胁迫导致根瘤气体渗透率降低，当干旱持续时，根瘤表面积随后也减小。在所有研究条件下，基于单位根瘤表面积的乙炔还原与根瘤气体渗透率高度相关（r = 0.92）。一项短期氧气富集研究表明，根瘤气体渗透率可能会限制氧气流入这些田间种植大豆的干旱胁迫根瘤和水分充足的根瘤。
