花生幼苗光合特性对弱光的响应

Response of photosynthetic characteristics of peanut seedlings leaves to low light

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(ФPSⅡ)和最大光化学效率(Fv/Fm)升高,叶绿素a/b和净光合速率(Pn)降低.恢复自然光照后1d,在高光强下测定时,随前期遮光程度增强,Pn、气孔导度(Gs)下降,细胞间隙CO2浓度(Ci)升高;在低光强下测定时,Pn显著升高,Gs和Ci下降;低光强与高光强下测定的Pn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,Pn、ФPSⅡ和Fv/Fm先迅速下降,3～5d后逐渐回升;恢复15d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、Pn、ФPSⅡ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.

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 cultivars 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 （ФPSⅡ）,and maximum PSⅡ photochemical efficiency （Fv/Fm） of test cultivars increased,while the Chl a/b ratio and photosynthetic rate（Pn） decreased. On the first day after light recovery,the Pn and stomatal conductance （Gs） decreased while the intercellular CO2 concentration （Ci） increased with increasing shading degree when measured under high light,but the Pn increased and the Gs and Ci decreased with increasing shading degree when measured under low light. The ratio of Pn measured under low light to that measured under high light increased significantly. With increasing shading degree,the light compensation point,light saturation point,CO2 compensation point,CO2 saturation point,and carboxylation efficiency decreased,while the apparent quantum yield increased. After the removal of shading,the Pn,ФPSⅡ,and Fv/Fm under natural light decreased immediately,but increased gradually 3-5 days after. 15 days after light recovery,the Pn,ФPSⅡ and Fv/Fm 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,Pn,and ФPSⅡ 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.