浅水勤灌水稻荧光参数与光合特性对不同施氮调控的响应

Response of Fluorescence Parameters and Photosynthetic Traits of Rice to Different Nitrogen Application under Sufficient Irrigation

【目的】探究浅水勤灌不同施氮量对寒地水稻荧光参数和光学特性的影响。【方法】于东北农业大学园艺试验站,采用盆栽试验,利用LI-6400XT型光合仪测定了龙粳32号水稻不同生育期6组施氮处理0、60、90、120、150、180kg/hm^2(简称为W0、W60、W90、W120、W150、W180)下的主要荧光参数和光合特性的变化。【结果】初始荧光Fo、最大荧光F_m、可变荧光F_v均随施氮量的增加而升高。PSII反应中心的光能转化效率F_v/F_m、潜在活性F_v/F_o、光化学淬灭系数q_p以及非光化学淬灭系数q_N均随施氮量的增加呈先升高后降低的趋势。W120、W150、W180处理与W0处理间出现显著差异次数多于W60、W90处理;净光合效率与气孔导度随施氮量增加而升高,而胞间CO_2摩尔分数降低,在施氮量达到150 kg/hm^2之后,光合速率降低,胞间CO_2摩尔分数增加。仅W150处理净光合效率、气孔导度、胞间CO_2摩尔分数、蒸腾效率与其他处理差异显著。说明PSII反应中心电子传递,光合初反应进程以及热耗散能力随施氮量的改变而受到促进或抑制,在W150处理下PSII反应最为活跃;对不同施氮处理进行光响应曲线模拟得出,随施氮量的增加光响应曲线上扬,光强大于400μmol/(m^2?s)后,在拔节—抽穗期光响应曲线随施氮量的增加而上升的幅度大于分蘖期。而对W120、W150、W180处理进行光响应特征参数的拟合得出,最大净光合效率P_(n max)表现为W150处理>W180处理>W120处理,光补偿点LCP与之相反,表观量子效率α、曲线曲角β以及暗呼吸速率R_d差异不大。【结论】浅水勤灌模式下,高氮比低氮更有助于水稻对光强的吸收,促进光响应发生,因此适当的高氮肥可以有效改善水稻叶片光响应特征,促进水稻生育,施氮量为150 kg/hm^2最佳。

【Objective】Nitrogen and soil water combine to affect physiological development of plants, and the purpose of this paper is to experimentally investigate the response of fluorescence parameters and photosynthetic traits to different nitrogen applications when soil moisture is not a limiting factor.【Method】Pot experiments were conducted at the experimental station of Northeast Agricultural University with japonica rice as the model plant. We examined six nitrogen levels： 0, 60, 90, 120, 150 and 180 kg/hm^2（referred to as W0, W60, W90, W120,W150 and W180 respectively thereafter）. At each growth stage, we measured the main fluorescence parameters and the photosynthetic traits using the LI-6400 XT photosynthetic apparatus.【Result】The initial fluorescence Fo,the maximum fluorescence Fmand the variable fluorescence Fvincreased with the applied nitrogen. The photo-energy conversion efficiency of PSII reaction center Fv/Fm, latent active Fv/Fo photochemical quenching coefficient qpand non-photochemical quenching coefficient qNall increased with the applied nitrogen first, and then decreased after reaching a peak. Compared with W60 and W90, W120, W150 and W180 differed more significantly from W0. With nitrogen application increasing, the net photosynthetic efficiency and the stomatal conductance both increased, while the inter-cellular CO2 molar concentration decreased. When nitrogen application reached150 kg/hm^2, the photosynthetic rate decreased while the intercellular CO2 molar concentration increased. The net photosynthetic efficiency, stomatal conductance, intercellular CO2 molar concentration and transpiration efficiency in W150 differed considerably from those in other treatments, suggesting that increasing nitrogen application either enhanced or impeded the central electron transport in PSII reaction, the initial photosynthetic rate and the thermal dissipation capacity. The PSII reaction was most active in W150, and regressing the light response to the nitrogen application indicated a positive correlation. When the light strength exceeded 400 μmol/（m^2·s）, the increase in the light response with the nitrogen during the jointing and heading stages was more significant than during the tillering stage. In W120, W150 and W180, the maximum net photosynthetic efficiency Pn maxwas ranked in W150W180W120, while the LSP, the light compensation point, and the light saturation point LCP went the opposite direction. The apparent quantum efficiency α, curve bend angle β and the dark respiration rate difference Rd did not show noticeable changes in all treatments.【Conclusion】When soil water is sufficient, increasing nitrogen fertilizer enhanced light absorption by leaves and promoted the light response. For our experiments, the optimal fertilizer application was 150 kg/hm^2.