不同氮形态叶面肥对油茶春梢叶片光合生理特性的影响

Effects of foliar fertilizer with different nitrogen forms on photosynthetic physiological characteristics of Camellia oleifera Abel spring shoot

【目的】探讨不同氮形态叶面肥处理对油茶春梢叶片光合作用的影响,为油茶林种植经营管理提供参考。【方法】以岑软3号为试验材料,设置4个不同含氮素形态配比的叶面肥处理,即N1~N4处理,分别添加尿素(酰胺态氮)、硫酸铵和硝酸钾按1:1(硝铵态氮)、硫酸铵(铵态氮)、硝酸钾(硝态氮),含纯氮量一致均配比中微量元素和生长物质,以只添加中微量元素与生长物质的处理为对照(CK)。测定各处理的油茶叶片光合参数和光合色素含量,并用直角双曲线模型等4种模型对不同处理的光合—光响应曲线进行拟合,评价不同氮形态叶面肥的肥效。【结果】在1000μmol/(m^(2)·s)光强下,不同氮形态叶面肥处理均可提高净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs),降低胞间CO_(2)浓度(C_(i)),其中铵态氮与硝态氮混施处理(N2)的P_(n)、G_(s)和T_(r)值均显著高于其他处理(P<0.05,下同),Ci显著低于其他处理。实测光响应曲线中,随光照强度增加,不同氮形态叶面肥处理均能使G_(s)、T_(r)和P_(n)值上升、Ci值下降,铵态氮与硝态氮混施处理的Gs、T_(r)和P_(n)上升更快,而Ci则表现为下降更快;通过光响应曲线拟合比较,得出最佳模型为直角双曲线修正模型。得出不同氮形态叶面肥处理均提高叶片的表观量子效率(α)和最大净光合速率(P_(n-max))值,其中铵态氮与硝态氮混施处理的α和Pn-max提高幅度最大,分别为0.072和8.5473μmol/(m^(2)·s);同时降低光补偿点(LCP)值,其中铵态氮与硝态氮混施处理的LCP值最小;提高了叶片光合色素含量,其中铵态氮与硝态氮混施处理的含量最高。【结论】不同氮形态叶面肥处理均有利于提高油茶春梢叶片光合作用,效果最佳的是以铵态氮与硝态氮混合配施的叶面肥。

【Objective】To study effects of treatments of foliar fertilizer with different nitrogen forms on Camellia oleifera Abel spring shoot’s leaf photosynthesis,and to provide reference for the planting,management and operation of C. oleifera Abel forest.【Method】Cenruan No. 3 C. oleifera Abel was used as the test material,and four treatments of foliar fertilizers with different nitrogen forms,namely N1-N4 treatments were set. Urea(amide nitrogen),ammonium sulfate and potassium nitrate at 1:1(ammonium nitrate nitrogen),ammonium sulfate(ammonium nitrogen),potassium nitrate(nitrate nitrogen)were added,in which pure nitrogen content was consistent with the proportion of medium and trace elements and growth substances,and the treatment with only medium and trace elements and growth substances was used as the control(CK). The photosynthetic parameters and photosynthetic pigment content in C. oleifera Abel leaves were determined and four models,such as rectangular hyperbolic model,were used to fit the photosynthetic-light response curves of different treatments to evaluate the fertilizer efficiency of foliar fertilizer with different nitrogen forms.【Result】Under 1000 μmol/(m^(2)·s)light intensity,all treatments increased the net photosynthetic rate(Pn),transpiration rate(T_(r)),stomatal conductance of leaves(G_(s)),and decreased the intercellular CO_(2)concentration(C_(i)). The values of Pn,Gsand Trof ammonium nitrogen and nitrate nitrogen treatment(N2)fertilization were significantly higher than those of other treatments(P<0.05,the same below),while the Ciof the treatment was significantly lower than that of other treatments.According to light response curve,as light intensity grew,treatments of foliar fertilizer with different nitrogen forms could make Gs,Trand Pnincrease but Cidecrease;in mixed ammonium nitrogen and nitrate nitrogen fertilization treatment,G_(s),T_(r) and Pnincreased faster while Cidecreased faster. According to light response curve fitting and comparison,the best model was the modified rectangular hyperbola model that helped reach the conclusions: treatments of foliar fertilizer with different nitrogen forms could increase apparent quantum efficiency(α)and maximum net photosynthetic rate(P_(n-max))of leaves and reduce light compensation point(LCP)value,in which mixed ammonium nitrogen and nitrate nitrogen fertilization treatment had the maximum increase of α and Pn-max,0.072 and 8.5473 μmol/(m^(2)·s)respectively. At the same time,it decreased light compensation point(LCP)value and mixed ammonium nitrogen and nitrate nitrogen fertilization treatment had the minimum LCP value;spraying foliar fertilizer containing nitrogen increased foliar photosynthetic pigment content whose highest value was witnessed in mixed ammonium nitrogen and nitrate nitrogen fertilization treatment.【Conclusion】Foliar fertilizers with different nitrogen forms are beneficial to improve the photosynthesis of C. oleifera Abel spring shoot leaves,and the best effect comes from foliar fertilizer mixed with ammonium nitrogen and nitrate nitrogen.