中文摘要：

为验证合理施氮对蔬菜生长的重要性,探讨了不同氮素胁迫对生菜叶片叶绿素荧光动力学参数的影响。本试验利用无土栽培法培植意大利全年耐抽抗热生菜（Lactuca sativa）,在出苗后25 d时,分别对生菜施加4种氮素水平的营养液：①重度氮胁迫（N1）纯氮14 mg/L;②轻度氮胁迫（N2）纯氮42 mg/L;③推荐供氮（N3）纯氮56 mg/L;④过量供氮（N4）纯氮84 mg/L。每5 d测量一次各组生菜叶片的叶绿素荧光图像,绘制相应的荧光参数变化曲线,研究各氮素浓度下生菜的叶绿素动态荧光参数变化规律。结果表明,氮素对最大光量子产量（Fv/Fm）影响较小,随着生育期的推移,各氮素水平下Fv/Fm参数均表现不同程度上升;过高或过低供氮时叶片实际光合效率[Y（Ⅱ）]呈现M形的波动变化,适量供氮时Y（Ⅱ）保持较高的稳定水平;氮素过高或过低时都将影响生菜的光能利用率,适量供氮下,叶片非光化学淬灭系数（qN）在整个生育期都处于稳定的较低水平。

英文摘要：

In order to verify the importance of reasonable nitrogen fertilizer on vegetable growth, effects of different nitrogen stress on chlorophyll fluorescence kinetics parameters of lettuce Lactuca sativa was investigated. Italian annual resistant bolting lettuce was planted in soilless method, and 4 nutrient solutions containing different nitrogen were sprayed in Lactuca sativa 25 days after the emergence. The 4 nutrient solutions were heavy nitrogen stress with pure nitrogen of 14 mg / L（N1）, light nitrogen stress with pure nitrogen of 42 mg / L（N2）, the recommended nitrogen of pure nitrogen of 56 mg / L（N3） and over nitrogen supply of pure nitrogen of 84 mg / L（N4）. Chlorophyll fluorescence images of Lactuca sativa leaves were measured once every 5 days. The corresponding fluorescence parameters change curve were drawn, and dynamic change rule of chlorophyll fluorescence parameters under different nitrogen concentrations was studied. The results showed that the nitrogen had little effect on Fv / Fm, and Fv / Fm increased to different extent under different levels of nitrogen along with the growth period. Y（Ⅱ） parameters fluctuated with M shape under low or excessive nitrogen, but Y（Ⅱ） stayed on stable top level under adapt nitrogen. Low or excessive concentrations of nitrogen had adverse effect on light usage, and qN stayed on stable and low level in the whole growth period under appropriate nitrogen.