高温季节草地早熟禾草坪质量与叶片抗氧化酶活性的变化

为探讨高温伏旱胁迫下草地早熟禾草坪质量的下降与其植物体生理活性的关系,本试验在南京夏季田间调查了6个草地早熟禾品种的草坪盖度、密度、综合质量、叶片叶绿素含量及叶片组织含水量、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和丙二醛(MDA)含量的变化。结果表明,随着夏季高温伏旱强度的增加和持续时间的延长,各品种的草坪盖度、密度、综合质量、叶片叶绿素含量和组织含水量均持续显著下降,8月中旬的草坪综合质量和叶片组织含水量分别比6月中旬降低了12.1%~27.6%和14.2%~27.6%;8月中旬叶片组织的SOD和POD活性分别比6月中旬下降了36.5%~55.0%和46.9%~65.7%,而MDA含量则增加了19.8%~88.7%。田间高温伏旱胁迫下草坪综合质量和叶片叶绿素含量、组织含水量、SOD与POD活性的降低幅度,以及叶片组织MDA含量的增加幅度均存在显著的品种间差异。较耐高温的“南农选系”和Midnight(W)在胁迫下的变化幅度明显小于不耐热的品种Bluechip、Sobra,以及耐热中等的品种America和Midnight(B),夏季草坪综合质量显著高于其它品种。相关分析结果表明,田间高温伏旱胁迫下草坪综合质量与叶片组织POD活性的下降幅度呈显著负相关。田间高温伏旱期间叶片组织保持较高的含水量和POD活性可能是草地早熟禾品种抗高温伏旱的重要标志之一。

Changes in turf quality and leaf antioxidants of Poa pratensis during high-temperatures in summer

Poa pratensis has been widely used for turf establishment in temperate regions,but the turf quality often declines significantly under high-temperature stress during summer.Tthe relationships between decrease of turf quality and physiological activities of Poa pratensis,on changes in coverage,tiller density,turf quality and contents in chlorophyll and water of leaves,activities of superoxide dismutase(SOD) and peroxidase(POD) and content of malondialdehyde(MDA) were assessed during the summer months on six cultivars in Nanjing.The results showed that coverage,tiller density,turf quality,leaf chlorophyll and water content declined markedly along with turgidity under the persisting stress of heat and drought.Compared with mid-June,turf quality and leaf water content in mid-August had declined about 12.1%-49.8% and 14.2%-27.6%, respectively.Similarly,the activities of SOD and POD in leaves declined 36.5%-55.0% and 46.9%-65.7%,respectively,while the MDA content increased from 19.8% to 88.7%.However,reduced turf quality,leaf water content,SOD and POD activities and the increased degree of MDA in summer differed significantly between cultivars.The extent of changes in Nannong and Midnight(W) lines were less than those of other cultivars,such as Bluechip and Sobra.Turf quality of Nannong line and Midnight(W) in summer was also higher than that of other cultivars.The correlation analysis indicated that a decrease in POD activity was negatively correlated with turf quality under field conditions.It suggests that higher POD activities and leaf water content may be important indicators associated with tolerance of heat and drought stress in Poa pratensis.