在黄土高原陇东旱地果园，比较了不同覆盖模式对苹果生育后期叶片叶绿素荧光动力学参数的影响，结果表明:叶绿素荧光诱导动力学曲线中的J相(2 ms)的相对可变荧光显著上升，在I相(30 ms)荧光强度趋于一致；不同处理在300 μs左右的特征位点处，叶绿素荧光产量较清耕显著降低，出现明显K点；CK的ΔWoj、ΔWok 值分别在K、L位点升高。综合分析认为，果园覆沙延长叶片在生育后期维持高水平的光合性能或延迟叶片衰老时间，覆膜与覆草处理叶片光合性能水平比清耕高，但显著低于覆沙处理。

The soil water thermal environment would different under different ground covers， to improve soil water thermal environment may influence the normal leaf senescence which delay nutrient re-flux， and reduce fruit quality. This study conducted in LongDong dry land orchards of the loess plateau， the chlorophyll fluorescence kinetics parameters of leaves under different covers are compared to support improvement and selection of ground-cover technology. The result shows that the relative variable fluorescence at J phase(2 ms) increased significantly， and at I phase (30 ms) which became consistent. At 300 μs sites， point of K appeared clearly and chlorophyll fluorescence yield decreased than CK significantly of the different treatments. The ΔWoj， ΔWok values of CK are higher in K and L sites than other treatments. So， sand-cover treatment delayed leaf senescence or maintained the highest photosynthetic performance level during late growth stage， Although the photosynthetic performance level of grass-cover and film-mulch treatments higher than CK， but they are much lower than sand-cover treatment.

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甘肃省农业科学院青年基金项目(2015GAAS27)；甘肃省青年科技基金计划(1308RJYA074)；国家现代农业(苹果)产业技术体系项目(CARS-28)；农业部园艺作物生物学与种质创制重点实验室项目(10218020)