花生幼苗光合特性对弱光的响应

在苗期用黑色遮阳网对丰花1号和丰花2号进行不同遮光处理(不遮光，遮光27%、43%和77%)，研究了苗期遮光及恢复对花生叶片光合特性的影响.结果表明： 遮光后，随遮光程度增强，叶片叶绿素含量显著增加，实际光化学效率(Ф_PSⅡ)和最大光化学效率(F_v/F_m)升高，叶绿素a/b和净光合速率(P_n)降低.恢复自然光照后1 d，在高光强下测定时，随前期遮光程度增强，P_n、气孔导度(G_s)下降，细胞间隙CO₂浓度(C_i)升高；在低光强下测定时，P_n显著升高，G_s和C_i下降；低光强与高光强下测定的P_n比值显著升高；恢复自然光照后，随前期遮光程度增强，光补偿点、光饱和点、CO₂补偿点、CO₂饱和点和羧化效率显著降低，表观量子效率显著升高.恢复自然光照后，P_n、Ф_PSⅡ和F_v/F_m先迅速下降，3～5 d后逐渐回升；恢复15 d后，遮光27%处理的各项指标恢复到对照水平，其他处理的恢复程度则因遮光程度和品种而异.丰花1号各处理叶绿素含量、P_n、Ф_PSⅡ均高于丰花2号.苗期遮光提高了花生利用弱光的能力，降低了其利用强光的能力.

Response of photosynthetic characteristics of peanut seedlings leaves to low light

To investigate the effects of shading and light recovery on the photosynthetic characteristics of peanut seedlings leaves, different shading treatments including no shading, 27% shading,43% shading, and 77% shading were performed with black sunshade net at the seedling stage of two peanut cuhivars Fenghua 1 and Fenghua 2, with related parameters determined. It was shown that with the increase of shading degree, the leaf chlorophyll content, actual PSII photochemical efficiency under irradiance (Φ_(PSⅡ) ) , and maximum PSⅡ photochemical efficiency ( F_v/F_m ) of test cuhivars increased, while the Chl a/b ratio and photosynthetic rate (P_n) decreased. On the first day after light recovery, the P_n and stomatal conductance ( G_s) decreased while the intercellular CO_2 concentration (C_i) increased with increasing shading degree when measured under high light,but the P_n increased and the G, and C_i decreased with increasing shading degree when measured under low light. The ratio of P_n measured under low light to that measured under high light increased significantly. With increasing shading degree, the light compensation point, light saturation point,CO_2 compensation point, CO_2 saturation point, and carboxylation efficiency decreased, while the apparent quantum yield increased. After the removal of shading, the P_n, Φ_(PSⅡ) , and F_v/F_m under natural light decreased immediately, but increased gradually 3-5 days after. 15 days after light recovery, the P_n, Φ_(PSⅡ) and F_v/F_m in treatment 27% shading recovered to the level of no shading. As for the other treatments, the restored extent differed with shading degree and test variety. In the same treatments, the leaf chlorophyll content, P_n, and Φ_(PSⅡ) of Fenghua 1 were higher than those of Fenghua 2. The results demonstrated that shading at seedling stage improved the capabilities of test varieties in using low light, but reduced the capabilities in using high light.