氮素施用量对饲用燕麦光合荧光特性的影响

Effect of Nitrogen Application on Photosynthetic Fluorescence Characteristics of Forage Oats

【目的】探究饲用燕麦光合荧光参数在不同氮素水平下的变化规律,明确施氮对饲用燕麦光合能力的影响机制。【方法】在内蒙古阴山北麓地区,以饲用燕麦为材料,设置了0、150、200、250、300、350 kg/hm^(2)共6个氮素施用量,研究不同生育期叶片的光化学猝灭系数(Photochemical quenching coefficient,qP)、非光化学猝灭系数(Non-photochemical quenching coefficient,NPQ)、光系统Ⅱ实际光化学效率(Actual photochemical quantum yield,Y(Ⅱ))、光系统Ⅱ最大光化学效率(Maximal photochemical efficiency,Fv/Fm)在不同氮素施用量的变化规律。【结果】随着氮素施用量的增加,饲用燕麦光合荧光参数Y(Ⅱ)值、Fv/Fm值和qP值均呈先增加后降低的变化规律;NPQ值呈先降低后增加的趋势,N_(250)处理NPQ值显著低于其他处理(P<0.05)。随着生育期推进,Y(Ⅱ)值和Fv/Fm值无明显变化,qP值和NPQ值则逐渐增加。【结论】适量增加氮素施用量有助于维持饲用燕麦PSⅡ反应中心系统的稳定性和提高光合能力;在阴山北麓地区种植饲用燕麦适宜的氮素施用量为250 kg/hm^(2)。

【Objective】To investigate the change rule of photosynthetic fluorescence parameters of forage oats under different nitrogen levels,and to clarify the influence mechanism of nitrogen fertilization on the photosynthetic capacity of forage oats.【Method】In this study,six nitrogen levels of 0,150,200,250,300 and 350 kg/hm^(2)were set in the Northern foothills of the Yinshan Mountains in Inner Mongolia,using forage oats as the material,to study the variation patterns of photochemical quenching coefficient(qP),non-photochemical quenching coefficient(NPQ),actual photochemical quantum yield,(Y(Ⅱ)),maximal photochemical efficiency(Fv/Fm)in leaves at different fertility stages under different nitrogen levels.【Result】With the increase of nitrogen application,the photosynthetic fluorescence parameters of forage oats Y(Ⅱ),Fv/Fm and qP all showed atrend of first increasing and then decreasing;NPQ showed the trend of decreasing and then increasing,and NPQ of N_(250)treatment was significantly lower than that of the other treatments(P<0.05).With the advancement of fertility period,Y(Ⅱ)and Fv/Fm did not have obvious pattern of change,while qP and NPQ showed a trend of gradual increase.【Conclusion】A moderate increase in the amount of nitrogen helps to maintain the stability of PS II reaction center system and improve the photosynthetic capacity of forage oats;the appropriate amount of nitrogen fertilizer for growing forage oats in the Northern foothills of the Yinshan Mountains is 250 kg/hm^(2).