施氮量对一年生黑麦草光合特性的影响

为了探究不同施氮量对一年生黑麦草(Lolium multiflorum Lamk.)光合特性的影响。本研究以‘特高’宽叶型一年生黑麦草为供试材料,采用盆栽试验,设置了4个处理组,分别为:CK对照组(不施肥)、C1低氮处理组(施鸡粪0.38 kg/m^2,即氮100 kg/hm^2)、C2中氮处理组(施鸡粪0.76 kg/m^2,即氮200 kg/hm^2)、C3高氮处理组(施鸡粪1.34 kg/m^2,即氮350 kg/hm^2)。利用Li-6400便携式光合仪测定开花期一年生黑麦草叶片的主要光合参数和光合特性的变化。结果表明:200 kg/hm^2施氮水平的表观量子效率(apparent quantum yield,AQY)和光饱和点(light saturation point,LSP)最高(分别为12.80 μmol·m^-2·s^-1和1 774.47 μmol·m^-2·s^-1),光能利用区间最大。350 kg/hm^2施氮水平下气孔导度(stomatal conductance,Gs)以及蒸腾速率(transpiration rate,Tr)显著低于其它处理,水分利用力(water use efficiency,WUE)强,但光呼吸速率(photorespiratory rate,Pr)较高,不利于干物质积累。同时,0?200 kg/hm^2施氮范围内,随着光照强度和CO2浓度的增加,各处理的净光合速率(net photosynthetic rate,Pn)均随之增加,但350 kg/hm^2施氮水平下叶片净光合速率的增加反而低于200 kg/hm^2施氮水平。合理的施氮量对黑麦草的光响应和CO2浓度响应曲线有明显的调节作用。在本试验条件下,施氮量为200 kg/hm^2最佳。

Effect of Different Amount of Nitrogen Supply on Photosynthetic Characteristics of Lolium multiflorum

In order to explore the effects of different nitrogen levels on the photosynthetic characteristics of Lolium multiflorum. In this study, the ’Tegao’ wide-leaf annual ryegrass was used as the test material. The pot experiment was used to set up four treatment groups: CK control group(without fertilization), and C1 low nitrogen treatment group(with chicken manure 0.38 kg/m2, nitrogen 100 kg/hm2), C2 medium nitrogen treatment group(chicken manure application 0.76 kg/m2, 200 kg/hm2 nitrogen), C3 high nitrogen treatment group(chicken manure application1.34 kg/m2, nitrogen 350 kg/hm2). The changes of photosynthetic parameters and photosynthetic characteristics of annual ryegrass leaves at flowering stage were measured by Li-6400 portable photosynthetic apparatus. The results showed that there were significant differences in photosynthetic response characteristics of light intensity and CO2 concentration at different nitrogen levels. The light quantum efficiency and light saturation point of the nitrogen level of 200 kg/hm2 was higher(12.80 μmol·mm-2·s-1 and 1 774.47 μmol·m-2·s-1, respectively). The stomatal conductance and transpira tion rate of the nitrogen level of 350 kg/hm2 were significantly lower than those of other treatments, and the water utilization ability was strong, but the photorespiration rate was higher, which was not conducive to dry matter accumulation. The results showed that photosynthetic rate of leaves among all treatments increased with the increasing of the light intensity and CO2 concentration in the range of 0~200 kg/hm2 nitrogen levels. However, the nitrogen level of 350 kg/hm2 were lower than that under nitrogen level of 200 kg/hm2. Under this experiment condition, the optimum nitrogen level was 200 kg/hm2.