用不同浓度 Ca(NO3) 2 · 4 H2 O(0 .7、1.4、2 .1g Ca2 + / kg土 )对 1年生的处在两种 Na Cl胁迫 (10和 2 0 g/ kg)处理下的木麻黄扦插苗进行化学调控 ,研究硝酸钙盐加氯化钠处理的木麻黄幼苗的生长量、木麻黄幼苗抗氧化酶系统活性和渗透调节物质的含量的变化 ,研究结果表明 :中度 Na Cl胁迫加硝酸钙处理下的木麻黄扦插苗的可溶性蛋白质含量增加 ,MDA含量降低说明膜脂过氧化作用减轻 ,而且抗氧化酶活性 (SOD、POD)之间协调变化有利于提高清除自由基的速率 ,中度盐胁迫下钙盐可以促进木麻黄体内脯氨酸的积累 ;但重度 Na Cl胁迫下钙盐对木麻黄的调控作用不显著 ,重度盐胁迫下钙盐反而降低木麻黄 SOD、POD活性和脯氨酸的含量 ,减弱了抗氧化酶系统对活性氧的清除作用 ,同时高浓度钙盐还会加重 Na Cl胁迫对木麻黄幼苗的损伤 ,这说明适量的钙盐有利于木麻黄幼苗抵抗盐胁迫能力的提高 ,而高浓度钙盐则可能会加重盐胁迫A regulation effect of calcium nitrate on clone seedlings of Casuarina equisetifolia under NaCl stress was made in pots, with two NaCl concentrations of 10g, 20g NaCl/kgsoil and three Ca(NO_3)_2 concentrations of 0.7g, 1.4g, 2.1g Ca~(2+)/kg soil, and treatments with pure NaCl without Ca(NO_3)_2 as control. Each pot was watered respectively with 1L corresponding salt solution every 6 days. To avoid too high stress causing the death of seedlings, the salt of each treatment was added into each pot in 30 days respectively, there were five pots in each treatment. The proline content, biomass, the activities of superoxide dismutase (SOD) and peroxidase (POD) of the seedlings in different experiments were determined and calculated after 60 days. Under NaCl stress and regulation effect of calcium nitrate, the activities of cell defense enzymes, lipid peroxidation and accumulation of osmolyte of Casuarina equisetifolia seedlings were analyzed and differences between treatments were compared. The experimental results showed that under mid NaCl stress (10‰ NaCl concentration) and calcium effect, the soluble protein content raised slowly with the increasing of Ca~(2+) concentration, the antioxidant enzymes activities of SOD、POD had similar trend in the plants, both of them took a trend of increasing firstly then decreasing with the increasing of Ca~(2+) concentration, the highest activities appeared when Ca~(2+) concentration was 0.7g/kg in soil. At the same time, malondialdehyde (MDA) content decreased firstly then increasing, showing the dissimilar trend to the activities of SOD and POD. But the MDA content in the plants with regulation effect of Ca(NO_3)_2 was lower than the control, which implied that the membrane lipid peroxidation and oxidative injure lightened. Free proline accumulation with calcium treatment was higher than that of the control (under 10‰ NaCl treatment). To Casuarina equisetifolia seedling under high NaCl stress (10 ‰ NaCl concentration ), the proper Ca~(2+) concentration was 0.7g/kg soil. The result showed there was no significant difference between treatments B (0.7g、1.4g、2.1gCa~(2+)+20g NaCl/g soil) and treatment A (0.7g、1.4g、2.1gCa~(2+)+10g NaCl/g soil). Compared with the seedlings under mid NaCl stress, the regulation effect of Ca(NO_3)_2 on the Casuarina equisetifolia seedling under high NaCl stress (20 ‰ NaCl concentration ) was not significant. All the physiological characteristics of seedling under high NaCl stress (10‰ NaCl) were lower than those of mid NaCl stress (20‰ NaCl). The biomass and the activities of SOD, POD and free proline content of the plants under 20‰ NaCl treatments increased a little as the increasing of Ca(NO_3)_2 concentration. Under Ca~(2+) 1.4g/kg treatment, activities of SOD and POD were the highest, respectively. But when Ca~(2+) concentration rose to 2.1g/kg, the characteristics such as the biomass, activities of SOD and POD and proline content were the lowest, and MDA content was increasing. It implied that the antioxidative enzymes were damaged by high salt stress, so the process of scavenging oxygen free radicals was slower and active oxygen was accumulated in cells. All results indicated that proper Ca~(2+) concentration could be selected to enhance the salt tolerance abilities of Casuarina equisetifolia cutting seedlings, but a high Ca~(2+) concentration would exacerbate salt stress and aggravate the damage of Casuarina equisetifolia seedlings under NaCl stress.国家自然科学基金资助项目 ( 3 0 170 190 ) ;; 福建省自然科学基金资助项目 ( D0 12 0 0 0 1)~
