氮素减施对茶树光合作用和氮肥利用率的影响

为探讨当前茶园施肥水平下氮素减施对茶树的生长与氮肥利用率的影响,在大田条件下设置不施氮(空白对照CK),纯氮16 kg·667 m^-2(减氮55.6%,处理A)、纯氮26kg·667 m^-2(减氮27.8%,处理B)、纯氮36 kg·667 m^-2(常规施氮CF)4个施氮处理,研究氮素用量减施对茶树光合作用、产量、氮素吸收及其利用效率的影响。结果表明:与CF比较,处理B能提高茶树的叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),降低胞间CO2浓度(Ci)和水分利用率(WUE);各施氮肥处理中以处理B的产量最高,氮肥农学效率最高,土壤养分剩余较少,氮素的利用效率较高;CF产量较处理B增加不显著,氮肥农学效率降低,土壤未利用养分较多。因此,减氮27.8%的施肥能保证与常规施肥的茶叶产量,氮素利用率明显提升,有利于茶业的可持续发展。

Effects of nitrogen fertilizer reduction on photosynthesis and nitrogen use efficiency in tea plant.

To examine the effects of nitrogen application level on the growth and nitrogen use efficiency of tea plant,we set four nitrogen fertilization treatments in the field:no nitrogen application(CK),applying pure nitrogen 16 kg·667 m^-2(reducing nitrogen by 55.6%,treatment A),applying pure nitrogen 26 kg·667 m^-2(reducing nitrogen by 27.8%,treatment B)and applying pure nitrogen 36 kg·667 m^-2(conventional fertilization,treatment CF).We examined the effects of different nitrogen application amounts on photosynthesis,yield,nitrogen absorption,and nitrogen use efficiency of tea plants.The results showed that treatment B promoted the chlorophyll content,net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr),but decreased the intercellular CO2concentration(Ci)and water use efficiency(WUE),compared to treatment CF.The yield of tea plant was the highest under treatment B,the agronomic efficiency of applied nitrogen fertilizer was the highest,the surplus of soil nutrients was less,and the efficiency of nitrogen utilization was high.The yield of tea plant was not significantly increased under treatment CF,the agronomic efficiency of applied nitrogen fertilizer was decreased,and there were more unutilized nutrients in soil.Therefore,compared with conventional fertilization,the yield of tea plant could be guaranteed and nitrogen use efficiency could be significantly improved under the condition of reducing nitrogen by 27.8%,which is beneficial to the sustainable development of tea industry.