水分胁迫下钙对大豆叶片光合作用的改善效应

Calcium Can Improve Photosynthesis of Soybean Leaves under Water Stress

本工作采用控制营养液中的钙量和叶片喷钙的方法来提高植株的钙水平,研究了钙对水分胁迫大豆光合作用的效应,结果表明:在水分胁迫下,经高钙处理（14mmol/L Ca^(2+)大豆叶片保持高的光合速率;中钙（5mmol/L Ca^(2+)）处理次之;低钙（营养液中不加Ca(NO_3)_2,而以NaNO_3代之）处理一周叶片光合作用速率最低,相对变化最大,在同样程度的水分胁迫下,高钙处理叶片具有较高的CO_2羧化效率,其光合作用由气孔限制向非气孔限制的转变亦较晚,田间喷钙,可以提高受旱大豆叶片的光合速率,高钙处理或喷钙增大了气孔对水分胁迫的反应能力,在水分胁迫下气孔阻力很快上升,抑制了水分过分消耗,而光合作用相对活性提高,高钙处理使细胞质膜和叶绿体膜系结构完整性提高,膜上酶活性增大。

The improvement on photosynthetic rates of soybean (Glycine max cv. Dongxie Xuan) leaves by calcium ions under water stress was studied with soybean seedings grown in three levels of Ca2+concentrations (high Ca2+: 14 mmol/L; medial Ca2+:5 mmol/L; and low Ca2+:0 mmol / L) for 7 days and with soybean seedlings grown in soil-medium pots whose leaves were sprayed with 0.132 mol/L Ca2+. Under osmotic stress (with PEG 6000, -0.5 MPa), the photosynthetic rate of high Ca2+ treatment leaves was the highest among three treatments and that of low Ca2+ treatments was the lowest; moreover, the photosynthetic rates of medial and low Ca2+ leaves had much sharper turn down than that of high Ca2+ leaves during early stress period (24 h), At the same degree of osmotic stress, high Ca2+ treatment leaves had the highest carboxylation efficiency, and its transferring of photosynthetic inhibition from stomatal to nonstomatal limitation took place later than that of medial and low Ca2+ treatments. The photosynthetic rate of soybean seedlings grown in soil-medium pots and sprayed with CaCl2 was improved during water stress period. Higher or Spraying-Ca2+ treatments increased the sensitivity of stpmatal regulation to water stress, while water stress took place, the stomatal resistance increased immediately, thus the water over-consumption was inhibited; however, the relative necessary for cells to maintain membrane system integration under water stress, especially for chloroplasts.