Abstract: In order to investigate the effects of Primo on the heat stress tolerance of perennial ryegrass,seedlings of heat-sensitive cultivar ‘Pinnacle’ were treated with Primo (1.95 mL·L^-1) for one week and then subjected to heat stress (35℃/30℃,day/night) for another twenty days. The canopy height,turf quality,chlorophyll content,electrolyte leakage,malondialdehyde (MDA) content,antioxidant enzyme activity (SOD,POD,CAT),Fv/Fm,photosynthesis and antioxidant gene expression levels were determined. The results demonstrated that plant growth,chlorophyll content,turf quality and photosynthesis decreased while EL,MDA content,SOD,POD and CAT activity increased under heat stress. Pretreatment with Primo reduced the canopy height,but increased chlorophyll content,Fv/Fm,net photosynthetic rate,stomatal conductance,transpiration rate,photochemical quench (qP),electron transport rate (ETR) and actual photochemical efficiency of PSⅡ (ΦPSⅡ) under heat stress. Pretreatment with Primo also induced a higher expression level of SOD,POD and CAT genes thus lead to a higher activity of antioxidant enzymes under heat stress. Those results indicated that Primo application reduced leaf stomatal and non-stomatal limitation to photosynthesis and alleviated the inhibition of PSⅡ reaction center that lead to an enhancement in light and dark reaction of photosynthesis and photosynthetic potential,along with the induced higher expression levels of key genes for sugar metabolism eventually contributed to the higher tolerance to heat stress in perennial ryegrass.

Key words: Primo, High temperature stress, Perennial ryegrass, Antioxidant enzymes, Photosynthesis

摘要： 为探讨浦绿对多年生黑麦草（Lolium perenne）耐热性的影响，以热敏感品种‘顶峰’（Pinnacle）为材料，研究了浦绿（1.95 mL·L^-1）预处理对热胁迫下（35℃/30℃，昼/夜）多年生黑麦草的草层高度和草坪质量、叶片细胞膜稳定性、丙二醛（Malondialdehyde，MDA）和叶绿素（Chlorophyll，Chl）含量、叶绿素荧光参数和气体交换参数、抗氧化酶活性及其基因表达的影响。结果表明，高温抑制了黑麦草的生长，显著降低了叶片Chl含量、草坪质量和叶片光合碳同化能力，提高了叶片电导率、MDA含量和抗氧化酶活性。浦绿预处理显著降低了黑麦草草层高度，提高了热胁迫下叶片Chl含量、净光合速率、气孔导度、蒸腾速率、光化学猝灭系数、电子传递速率和PSⅡ实际光化学效率，降低了非光化学猝灭系数，增加了叶片抗氧化酶基因的表达和酶活性，降低了叶片气孔和非气孔限制，缓解了高温对叶片PSⅡ反应中心的抑制，从而提高了黑麦草的耐高温能力。综上所述，浦绿可有效提高多年生黑麦草的耐热性，从而提高其坪用性能。

关键词: 浦绿, 高温胁迫, 黑麦草, 抗氧化酶, 光合作用