Under the condition of lack of magnesium, effects of magnesium application on the photosynthetic rate and chlo-rophyll fluorescence of grape were studied in order to provide reference basis for formulating rational fertilization technique of grape. A field experiment with a split plot design was conducted, four soil gradient of 0, 112.5, 150, 187.5 kg/ hm2was set up in the main area, three concentrations of foliar spraying, which was 0%, 0.2%, 0.4%, respectively, was set up in the deputy district. The results showed that soil application and foliar spraying of magnesium fertilizer significantly im-proved the magnesium content in leaf, when soil application with 150 kg/hm2and foliar spraying of 0.4%magnesium fertiliz-er, the leaf chlorophyll content, net photosynthetic rate, Yield, ETR, Fv/Fm, qP, qN are maintained at a higher level, but F0was at the lowest level. A moderate amount of magnesium supplement significantly increased magnesium and chloro-phyll content in the leaves, increased the net photosynthetic rate, increased non-photochemical dissipation of PSⅡ antenna pigment, relieved damage optical system, at the same time, maintained PSⅡin situ light energy conversion efficiency and potential activity, but when too much magnesium was applied, stomatal conductance decreased, which resulted in a decline of net photosynthetic rate.%探讨大田条件下,施镁对缺镁葡萄叶片光合速率和叶绿素荧光特性的影响,为葡萄科学施肥提供理论依据.采用裂区试验,主区设4个土施硫酸镁梯度,为0、112.5、150、187.5 kg/hm2,副区设3个叶面喷施硫酸镁浓度,分别是0%、0.2%、0.4%.土施和叶面喷施镁肥能够显著提高叶片镁含量,土施150 kg/hm2同时叶面喷施0.4%硫酸镁肥后,叶片叶绿素含量、净光合速率、实际光量子产量、表观光合电子传递速率、原初光化学效率、光化学淬灭、非光化学淬灭维持在较高水平,初始荧光最低.缺镁土壤适量施镁(如土施150 kg/hm2同时叶面喷施0.4%硫酸镁肥) 能够显著增加叶片中镁和叶绿素含量,提高净光合速率,增加PSⅡ天线色素的非光化学能力耗散,缓解光系统受损程度,同时保持 PSⅡ原处光能转换效率和潜在活性,但施镁量过大,气孔导度降低,净光合速率下降.
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