不同耐盐性花生品种对NaCl胁迫的光合和抗逆生理响应特征

以较耐盐花生品种‘花育25’、‘鲁花12’和盐敏感品种‘海花1’、‘花育20’为材料，采用盆栽试验，设置0、1.0、2.0、3.0 g/kg土壤NaCl胁迫浓度梯度，测定其净光合速率、表观量子效率、气孔导度等光合特性，以及抗氧化酶活性和渗透调节物质含量等指标，明确NaCl胁迫条件下不同耐盐性花生品种光合和生理生化特性的适应特征。结果表明：(1)NaCl胁迫明显抑制各品种花生叶片光合作用，净光合速率随盐胁迫浓度的升高呈明显降低的趋势。(2)各品种花生叶片净光合速率均先随光照强度的增强而升高，当光强达到一定数值时趋于平稳；光补偿点和光饱点因品种和盐胁迫浓度差异较大，较高的盐胁迫浓度使叶片光补偿点升高，盐敏感品种的光饱和点降低。(3)盐胁迫条件下，各品种叶片表观量子效率和最大净光合速率均随盐胁迫强度的增加呈显著降低趋势，盐敏感品种利用弱光的能力在低盐胁迫下强于耐盐品种，其最大净光合速率在较高盐胁迫浓度(3.0 g/kg)下明显低于耐盐品种，但两类品种的叶片表观量子效率降幅相近(78.65%~88.00%)。(4)在NaCl胁迫下，耐盐品种叶片自由水含量显著高于盐敏感品种；在2.0～3.0 g/kg NaCl胁迫下，耐盐品种叶片SOD、CAT、POD活性和MDA含量的升降幅度均低于盐敏感品种；耐盐品种在NaCl浓度低于2.0 g/kg时的抗氧化能力明显高于盐敏感品种。研究发现，盐胁迫下花生品种抗盐耐逆的主要生理响应特征是提高光补偿点和最大净光合速率，增强叶片持水能力和物质代谢能力，以及提升抗氧化和渗透调节能力。

Physiological Response Characteristics of Peanut Varieties with Different Salt Resistance under NaCl Stress

In order to clear the salt adaptive mechanisms of photosynthesis and physio biochemistry of different peanut varieties in salt stress, we conducted pot experiment by setting 0, 1.0, 2.0, 3.0 g/kg NaCl concentration gradient, and tested the physiological index of salt tolerant peanut varieties (HY25, LH12) and salt sensitive varieties (HH1, HY20), including photosynthetic traits (photosynthetic rate, apparent quantum efficiency and stomatal conductance), antioxidant enzyme activities and contents of osmotic regulatory substances. The results showed as follows. (1) The NaCl stress significantly inhibited photosynthesis of peanut leaves. The net photosynthetic rate decreased obviously with the increase of salt stress concentration. (2) The net photosynthetic rate of peanut leaves increased with the increase of light intensity, but it would level off when the light intensity reached a certain value. The difference of light compensation point and light saturation point was great among different peanut varieties or salt concentrations. The high salt stress concentration increased the light compensation point of leaves, but decreased the light saturation point of salt sensitive cultivars. (3) The apparent quantum efficiency and maximum net photosynthetic rate decreased significantly with the increase of salt stress intensity. The ability of using weak light in salt sensitive varieties were stronger than that in salt tolerant varieties under low salt stress. In the stress of 3.0 g/kg NaCl concentration, the maximum net photosynthetic rates of salt sensitive varieties were significantly lower than that of salt tolerant varieties, while the apparent quantum efficiency of the two species leaves had similar drop among 78.65%-88.00%. (4) The free water content of salt tolerant variety leaves was significantly higher than that of salt sensitive variety leaves in salt stress. In 2.0-3.0 g/kg NaCl stress, the fluctuation of SOD, CAT, POD activities and MDA content in salt tolerant varieties were lower than that in salt sensitive varieties. The antioxidant capacity of salt tolerant varieties was significantly higher than that of salt sensitive varieties when NaCl concentration was less than 2.0 g/kg. The study found the major reasons that plants could tolerant salt stress were the increase of light compensation point, maximum net photosynthetic rate, leaves preserve water ability, metabolism, antioxidant and osmotic regulation ability under salt stress.