青杨雌雄叶片气孔分布及气体交换的异质性差异

利用网格和二维成图的方法对青杨雌雄叶片各区域的气孔分布及气体交换特性进行了测定.结果表明:1)除气孔密度(SD)外,雌雄植株在气孔长度(SL)、宽度(SW)和比值(SR)方面具有显著差异(P=0.000,P=0.000和P=0.002).雌株的SL和SW分别比雄株的高51.86%和67.06%,而SR则比雄株的低11.46%.从雌株和雄株的叶面分布来看,SD均为叶中>叶尖>叶基,SL均为叶尖>叶中>叶基,SW的最小值同在叶基部,但最大值分别在叶中和叶尖部.雌株的SR表现为叶基>叶尖>叶中,雄株却正好相反.2)在净光合速率(Pn)上雌株明显低于雄株.雌株的Pn叶基最低(Pn值介于2.00～3.00?μmol m-2 s-1),叶尖最高(Pn值介于8.00～9.00?μmol m-2 s-1),总体上表现出沿叶基到叶尖逐渐增大的趋势.雄株的Pn在叶面的分布也有差异,但总体规律不明显.3)从叶面各区间的气体交换来看,雌株的蒸腾速率(Tr)和气孔导度(Gs)变化不大,雄株的Tr和Gs呈现叶尖和叶中部高于叶基部的明显趋势.雌株的胞间CO2浓度(Ci)为叶基>叶中>叶尖,气孔限制值(Ls)与此相反.而雄株的Ci在叶面的变化较大,Ls呈现沿叶尖至叶基方向逐步上升的趋势.上述结果表明,青杨雌雄叶片在气孔分布及气体交换特性上不仅存在显著的性别差异,而且具有明显的叶面区域异质性.

Sex-specific Heterogeneity in Stomatal Distribution and Gas Exchange of Male and Female Populus cathayana Leaves

In this experiment, we investigated sex-ielated heterogeneity in stomatal distribution and gas exchange on leaves of male and female trees of Populus cathayana using grids measurement and 2-D contour maps. There were significant differences in stomatal length (SL), stomatal width (SW) and stomatal ratio (SR) between leaves of female and male and the significant variations were P = 0.000, P = 0.000 and P = 0.002, respectively. Compared with leaves of male trees, SL and SW in leaves of female trees increased 51.86% and 67.06% , respectively, while SR in which decreased 11.46% . Moreover, the patterns for stomatal density (SD) as "middle zones > apical zones > basal zones" and for SL as "apical zones> middle zones> basal zones" were found in both male and female leaves. The patterns for SW were observed as "middle zones > apical zones > basal zones" in female leaf and "apical zones > middle zones > basal zones" in male leaf. It was also detected that the patterns for SR in female leaf as "basal zones > apical zones > middle zones" was opposite to that in male leaf. Significant difference was found in distribution pattern of net photosynthetic rate (Pn) between female and male leaves. Pn of female leaf was lower in base regions (2.00-3.00 μmol m~(-2) s~(-1)) while higher in front regions (8.00 -9.00 μmol m~(-2) s~(-1) ), and increased gradually from basal to apical zones. However, Pn of male leaf didn't show certein pattern. The transpiration (Tr) and stomatal conductance (Gs) showed significant lower value in basal zones on male leaf comparing with famale leaf. Furthermore, CO_2, concentration (Ci) showed pattern as "basal zones > middle zones > apical zones", which was opposite to stomatal limiting value (Ls), were observed on female leaf. Only Ls was found increased gradually from apical to basal zones although Ci and Ls varied obviously in each zones. To summarize, our result showed that there were significant differences in heterogeneity of stomatal distribution and gas exchange on male and female Populvs cathayana leaves.