指数施肥对美国山核桃苗期光合生理特性的影响

Effects of Exponential Fertilization on the Photosynthetic Physiology Characteristics of Carya illinoinensis Seedlings

为探究施肥对美国山核桃幼苗光合生理特性的影响,以一年生美国山核桃实生苗为试验材料,共设置0(CK),100,200,400,600,800mg/株6个不同供氮水平的施肥处理,运用指数施肥法研究了6种氮素施肥处理下美国山核桃生长及光合生理特性的变化。结果表明:(1)美国山核桃幼苗的苗高、地径、生物量随着施氮量的增加均呈现出先增后减的趋势,分别在N600处理(600mg/株)取得最大值33.4cm,5.08mm和9.33g;根冠比随着施氮量的增加而呈现递减趋势,在N800处理取得最小值0.39。(2)叶片叶绿素a,b与总量均随施氮量的增加而增加。(3)光合气体交换参数净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)及蒸腾速率(Tr)随着施氮量的增加均呈现先增加后减小的趋势,且均在N600处理达到最大值,分别是10.53μmol/(m^2·s),0.192 mol/(m^2·s),241.7μmol/mol,2.85mmol/(m^2·s)。(4)叶片PSⅡ的最大量子产额(Fv/Fm)、实际最大量子产额(Yield)、光化学淬灭系数(Qp)和表观光合量子传递速率(ETR)均随着施氮量的增加呈现出先增后减的趋势,分别在N600处理(600mg/株)达到最大值0.795,0.356,0.379,23。这些结果表明:施氮量为600mg/株时能够显著提高其光合速率和叶绿素荧光参数,促进幼苗的生长,故600mg/株左右为美国山核桃温室培育条件下的最佳施氮量。

An exponential fertilization experiment was conducted with six dose levels（applying a total of 0,100,200,400,600,800 mg/seedling in this experiment）of nitrogen to assess the effects on different nitrogen levels on the photosynthetic characteristics of pecan seedlings.The objective of this study was to reveal the nitrogen demand and determine the optimal nitrogen amount for pecan seedlings.The results indicated that：（1）the height,ground diameter and biomass of pecan seedlings increased as the nitrogen fertilization increased from 0 to 600 mg/seedling and then decreased with the nitrogen fertilization increased from 600 to800 mg/seedling;the maximum values were 33.4 cm,5.08 mm and 9.33 g/seedling,respectively;the root shoot ratio decreased with the nitrogen fertilizer increased;（2）chlorophyll a,chlorophyll b and total chlorophyll increased with the nitrogen fertilizer increased;（3）the net photosynthetic rate,stomatal conductance,intercellular CO2 concentration and transpiration rate of pecan seedlings increased as the nitrogen fertilizer increased from 0 to 600 mg/seedling and then decreased with the nitrogen fertilizer increased from 600 to 800 mg/seedling.The maximum values were 10.53μmol/（m-2·s）,0.192 mol/（m-2·s）241.7μmol/mol and2.85 mmol/（m-2·s）,respectively;（4）Fv/Fm,Yield,Qp,ETR increased until the nitrogen application rate of 600 mg/seedling,with the highest values of 0.795,0.356,0.379 and 23,respectively.Based on these data,it could be concluded that 600 mg/seedling would be the optimal nitrogen amount for Caryaillinoinensis seedlings in greenhouse.