施肥对紫花苜蓿分枝期光合特性的影响

【目的】研究不同施肥处理对3年生紫花苜蓿分枝期净光合速率、蒸腾速率、气孔导度等植物生理因子的影响。【方法】以加拿大进口紫花苜蓿品种——阿尔岗金为材料，采用美国LI-COR公司生产的LI-6400便携式光合作用测定系统进行测定。【结果】施氮10kg/hm2光合速率极显著地高于不施氮处理，施氮比不施氮光合速率高出8.07 μmolCO2/m2·s (24.05%)；施氮10kg/hm2对水分利用率的提高具有明显的作用，氮磷配施效果更好，以P40N10配施效果最好，P20N10次之；施磷20kg/hm2叶片蒸腾速率、气孔导度和胞间CO2浓度都最高，分别达到了14.88mmolH2O /m2·s、1.01 cm/s和300μmol/mol【结论】苜蓿施氮10kg/hm2有助于提高分枝期叶片光合速率、水分利用效率。在施氮10kg/hm2水平下，施磷20—40kg/hm2范围内，随施磷量的增加水分利用率提高。施磷20kg/hm2对提高叶片蒸腾速率效果显著，并且能明显提高气孔导度和胞间CO2浓度。

Effect of Fertilization on the Photosynthetic Characteristics of Alfalfa(Medicago sativa) in its branching period

ObjectiveThe photosynthetic rate, transpiration rate, stomata conductance of 3 year-old alfalfa in its branching period were studied under different fertilizing treatments.MethodUsing LI-6400 portable photosynthesis measurement system of LI-COR company.ResultThe photosynthetic rate of fertilizing nitrogen 10kg/hm2.ConclusionFertilizing nitrogen 10kg/hm2 could increase the photosynthetic rate, water use efficiency (WUE) of alfalfa leaf. Based on fertilizing nitrogen 10kg/hm2, fertilizing phosphorus 20~40kg/hm2 could increase WUE with increments of fertilizing phosphorus. Fertilizing phosphorus 20 kg/hm2 could increase transpiration rates of leaves and markedly improved the stomata conductance and intercellular CO2 concentrations.