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作者	单位
张鑫，孔祥，李勇，骆永丽，黄翠，金敏	(1.山东农业大学农学院/作物生物学国家重点实验室，山东泰安 271018； 2.山东农业大学生命科学院，山东泰安 271018)

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中文摘要:

为给外源脱落酸(ABA)在小麦抗旱栽培中的合理利用提供理论依据，以耐旱型品种山农20和水分敏感型品种辐287为材料，研究外源ABA对花后干旱条件下小麦冠层温度、光合特性、籽粒灌浆及产量的影响。结果表明，干旱处理显著降低了小麦吸收光能性能指数（PI_abs）及被捕获电子传递到电子传递链Q_A^-中下游其他电子受体的概率（φ₀），尤其在灌浆后期，PI_abs及φ₀降幅均达到50%以上，导致叶片净光合速率、蒸腾速率及气孔导度显著下降和冠层温度显著升高。同时，干旱处理下两品种的最大灌浆速率及平均灌浆速率均呈现降低趋势。两品种花后光合积累量及花后贮藏同化物转运量对籽粒产量的贡献率均显著降低，辐287降幅大于山农20。最终表现为粒重及产量显著降低。干旱条件下喷施ABA可以显著提高PI_abs值、φ₀值、净光合速率及叶绿素相对含量，延缓叶绿素降解，诱导气孔适当关闭，减少水分散失，降低冠层温差。同时ABA处理提高了强势粒最大灌浆速率、平均灌浆速率，延长了生长活跃期，降低穗叶温差，花后光合积累量及花后同化物转运量对籽粒产量的贡献率显著升高，最终表现为粒重及产量提高。这说明耐旱型小麦品种叶片光合同化力强，花后干物质转运效率较高，有利于籽粒灌浆增重，实现产量提高；外源喷施ABA可以提高灌浆期水分亏缺条件下小麦的光合性能，显著降低穗叶温差，优化同化物分配比例，最终实现小麦的抗旱稳产。

英文摘要:

In order to provide a theoretical basis for the rational utilization of wheat cultivars response to exogenous abscisic acid(ABA) under drought stress conditions,the effects of exogenous ABA on canopy temperature, photosynthetic characteristics, grain filling and yield of wheat under drought conditions were studied. Two wheat varieties,the drought-tolerant variety Shannong 20(SN20) and water-sensitive variety Fu 287(F287) were used. The results showed that, drought stress significantly reduced PI_abs(the photosynthetic performance index) and φ_o(the probability that a trapped exaction transfers an electron into the electron transport chain beyond Q_A^-).In the late filling stage, the PI_abs and φ₀ were declined by over 50%. The net photosynthetic rate, transpiration rate and stomatal conductance of the flag leaves were decreased significantly, whereas, the canopy temperature was enhanced remarkably.Additionally, the maximum filling rate and average filling rate of the two varieties under drought treatment showed a decreasing trend.The assimilate transportation amount after anthesis and the contribution of assimilate transportation amount after anthesis to grain of both varieties were significantly reduced. The decrease of F287 was greater than that of SN20. Accordingly, there was a significant reduction in grain weight and yield under drought conditions.The parameters of PI_abs, φ_o, net photosynthetic rate and SPAD value were significantly increased by ABA treatment under drought conditions.Spraying ABA could also delay chlorophyll degradation, induce stomata closureproperly, reduce water loss, and decrease canopy temperature depression.Meanwhile, exogenous ABA increased the maximum grain filling rate, average grain filling rate and prolonged the active growth duration, which led to the decrease of the temperature depression between spike and leaves, the enhancement of the assimilates transportation amount after anthesis and the contribution of assimilates transportation amount after anthesis to grain.As a result, grain weight and yield were improved.The above results suggested that the drought-tolerant varieties maintain high capacity of photosynthetic assimilation and increase dry matter transport rate after anthesis, which was beneficial to grain filling and yield improvement.Exogenous ABA improved the photosynthetic performance of wheat under water stress during the grain filling stage, significantly reduced the temperature depression between spike and leaves and optimized the distribution ratio of assimilate.Therefore, drought tolerance and yield stability of wheat can be achieved.

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