氮素浓度对黄檗幼苗生长的光合特性及叶绿素荧光动力学研究

Study on Photosynthetic Characteristics and Chlorophyll Fluorescence Kinetics of Phellodendron amurense Seedling Growth under Different Nitrogen Concentrations

摘要: 为研究氮素营养对黄檗幼苗生长和光合生理的影响，以当年生水培黄檗幼苗为实验材料，在0、2、8、16 mmol•L⁻¹四种不同氮浓度条件下，探讨不同氮素营养对黄檗幼苗生长、光合作用和叶绿素荧光等的影响。结果表明，随着氮浓度的提高，黄檗幼苗的鲜重、干重、基径和侧根长度、净光合速率(P_n)、表观量子效率(AQY)、光饱和点(LSP)、气孔导度(G_s)和蒸腾速率(T_r)均呈先上升后下降的趋势，且均在8 mmol•L⁻¹处理时达到最大值，而光补偿点(LCP)则呈持续下降趋势。最大荧光(F_m)、PSII最大光化学效率(F_v/F_m)、PSII反应中心光捕获效率(F_v'/F_m')、快速叶绿素荧光诱导曲线(OJIP曲线)均以氮浓度为8 mmol•L⁻¹时最高。不同施氮素水平(N2、N8和N6)下，黄檗幼苗叶片的光化学淬灭系数(qP)均明显高于不施氮素水平(N0) (P < 0.05)，并随着氮浓度的增加，qP呈降低趋势；而非光化学淬灭系数(NPQ)则整体呈增加趋势。综合上述研究内容，氮素浓度在8 mmol•L−1时最有利于黄檗幼苗的生长且可以充分发挥其光合能力，这对黄檗苗木资源培育营养管理与调控提供了指导意义。

Abstract: In order to study the effects of nitrogen nutrition on the growth and photosynthetic physiology of Phellodendron amurense seedling, the hydroponic seedling of P. amurense was used as experimental material, the effects of different nitrogen nutrition on the growth, photosynthesis and chlorophyll fluorescence of P. amurense seedlings were investigated under the conditions of 0, 2, 8, 16 mmol•L⁻¹. The results showed that with the increase of nitrogen concentration, the fresh weight, dry weight, base diameter and lateral root length, net photosynthetic rate (P_n), apparent quantum efficiency (AQY), light saturation point (LSP), stomatal conductance (G_s) and transpiration rate (T_r) of P. amurense seedlings were firstly increased and then decreased, and all reached the maximum value when the nitrogen concentration was 8 mmol•L⁻¹. While the light compensation point (LCP) showed a trend of continuous decreasing with the increase of nitrogen concentration. Maximum fluorescence (F_m), maximum photochemical efficiency of PSII (F_v/F_m), photo capture efficiency of PSII reaction center (F_v'/F_m') and rapid chlorophyll fluorescence induction curve (OJIP curve) were the highest when nitrogen concentration was 8 mmol•L⁻¹. Under different nitrogen application levels (N2, N8 and N6), the photochemical quenching coefficient (qP) of leaves of P. amurense seedlings was significantly higher than that without nitrogen application (P < 0.05), and qP showed a decreasing trend with the increase of nitrogen concentration (N0). However, the non-photochemical quenching coefficient (NPQ) showed an overall increasing trend. In conclusion, the nitrogen concentration of 8 mmol•L⁻¹ was found to be the most favorable for the growth of P. amurense seedlings and to give full play to their photosynthetic capacity, which provided guidance for the nutrient management and regulation of P. amurense resources cultivation.