氮素对模拟胁迫下土沉香幼苗抗旱生理的影响

以土沉香3个种源的幼苗为材料,用PEG6000模拟水分胁迫,研究氮素营养与水分胁迫对土沉香不同种源幼苗相关生理生化指标的耦合影响.结果表明:不同处理的相对电导率、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、游离脯氨酸(Pro)质量分数和丙二醛(MDA)质量摩尔浓度差异显著.正常水分条件下,高氮处理(氮素浓度为15 rtmol/L)有利于提高抗氧化酶(SOD,POD,CAT)活性和Pro质量分数,但造成一定程度的渗透胁迫,使MDA质量摩尔浓度和相对电导率升高.水分胁迫条件下,高氮处理的相对电导率、MDA质量摩尔浓度均小于低氮处理(氮素浓度为7.5 mmol/L),而CAT活性、Pro质量分数大于低氮处理,POD活性对氮素营养及水分处理不敏感.3个种源之间相对电导率差异显著,高低顺序为琼中种源＞临高种源＞澄迈种源.尽管3个种源的SOD和CAT活性以及Pro质量分数和MDA质量摩尔浓度略有不同,但在-0.63 MPa水分胁迫条件下,高氮处理有利于提高3个种源的抗旱性.

Effects of Nitrogen Nutrition on Physiological Traits of the Aquilaria Sinensis Seedlings Under Simulated Water Stress

An experiment of taking three Aquilaria sinensis provenances, two levels of nitrogen supply and two levels of water stress by PEG-induced, was conducted to study the response of physiological and biochemical indices. The results showed that the different nitrogen supply and water stress levels had significant effects on the relative conductivity, the superoxide dismutase(SOD)activity, proline mass fraction and malondialdehyde(MDA) molality. Under the appropriate water condition, although the high nitrogen supply was beneficial to improve the antioxidant enzyme activity and free proline mass fraction, it caused a certain degree of osmotic stress, representative by the increasing of MDA molality and relative conductivity. Under the water stress condition, the relative conductivity and the molality MDA of the high nitrogen treatment were lower than that of the low nitrogen treatment, on the contrary, for the catalase(CAT)activity and free proline mass fraction. The peroxidase(POD) activity was not actively responded by the nitrogen supply and water stress. There was significantly difference in relative conductivity among the three provenances. The value in Qiongzhong provenance was higher than that of Chenmai provenance, and that of Lingao provenance was between them. Although SOD activity and CAT activity, as well as proline mass fraction and MDA molality were some different among the three provenances, high nitrogen supply was helpful for improving their drought resistance under - 0.63 MPa water stress conditions.