灌浆期不同株龄老芒麦旗叶对光照强度的响应及光合基础环境指标差异

Response of Elymus sibiricus flag leaves at differentplant ages to light intensity and differences in theirbasic photosynthetic environmental indicatorsduring filling stage

摘要:

利用人工模拟光源研究了在高寒区同一生境下,不同株龄老芒麦旗叶净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)、气孔限制值(Ls)及水分利用效率(WUE)随光照增强的响应差异,同时分析各株龄老芒麦旗叶的光合基础环境指标差异。结果表明:株高由高到低为3株龄＞4株龄＞5株龄,且各株龄间差异显著(P＜0.05);4株龄老芒麦旗叶的叶长和叶面积均较大,且与3株龄或5株龄差异显著(P＜0.05)。在200~2 000 μmol/(m2·s)光子量照度,各株龄老芒麦旗叶Pn和Tr均为3株龄＞4株龄＞5株龄,且二者呈极显著正相关关系(P＜0.01)。Pn与Gs或Ls呈极显著正相关,Pn与Ci呈极显著负相关(P＜0.01)。主要受气孔限制因素的影响,3和4株龄老芒麦旗叶分别在光子量照度为1 200和1 000 μmol/(m2·s)时出现光抑制现象,而5株龄在800 μmol/(m2·s)时,主要受到非气孔限制因素影响表现为光抑制。光子量照度极显著影响旗叶Pn和Gs(P＜0.01),株龄极显著影响Ci(P＜0.01),二因素共同作用时,显著影响老芒麦旗叶Pn和Gs(P＜0.05)。

Abstract:

Photosynthetic characteristics,including net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),intercellular CO2 concentration(Ci),stomatal limited value(Ls)and water use efficiency(WUE),were determined on flag leaves of Elymus sibiricus with different plant ages while grown in the same habitat of alpine regions,under varying light intensity using simulated light source.The resulted showed that there were significant differences in plant heights of E.sibiricus with different plant ages(P＜0.05),which followed the order of 3-year-old plants ＞ 4-year-old plants ＞ 5-year-old plants.Leaf length and leaf area of flag leaves from 4-year-old were significantly greater than those of 3-year-old or 5-year-old plants(P＜0.05).Under light intensity ranging from 200~2 000 μmol/(m2·s),Pn and Tr values of flag leaves with different plant age followed the order of 3-year-old＞4-year-old＞5-year-old plants;and they had a positive correlation regardless of plant age(P＜0.01).There was a significant and positive correlation between Pn and Gs or Ls,while a negative correlation between Pn and Ci(P＜0.01).The E.sibiricus flag leaves from the 3-year-old and 4-year-old plants showed photo-inhibition at the light intensity of 1 200 and 1 000 μmol/(m2·s),respectively,primarily due to stomatal limitations.The flag leaves of 5-year-old E.sibiricus showed photo-inhibition at 800 μmol/(m2·s),primarily due to non-stomata limitations.Pn and Gs of flag leaves were significantly affected by light intensity(P＜0.01)and the two-way interaction of light intensity and plant age(P＜0.05),while Ci of flag leaves was affected by plant age(P＜0.01).