冬小麦群体叶片气孔导度差异性分析

VARIATION OF LEAF STOMATAL CONDUCTANCE IN WINTER WHEAT CANOPY

对冬小麦 (Triticum aestivum L.)两个品种 3个生育期测定和分析了群体叶片的气孔导度。结果表明 ,近轴面气孔导度比远轴面的大 ,二者之比呈近似正态分布 ,最大概率出现约为 1 .5,该比值在冠层垂直方向变化不显著 ,但随季节而变 ,抽穗期最大。叶片气孔导度从冠层顶部向下迅速递减 ,递减系数约为 0 .57,且各层日变化大致平行。冠层上部气孔活跃 ,导度日变化明显 ,下部日变化不大。同一叶片的气孔导度由近轴面的叶基 ,经由其叶中、叶尖 ,翻过尖点 ,再从远轴面的叶尖经叶中向叶基递减。对近轴面叶中、叶尖气孔导度与该面平均气孔导度相关系数较大 ,而对远轴面叶中、叶基气孔导度与该面气孔导度相关系数较大 ,据此建议测定近轴面气孔导度时 ,应以叶中、叶尖部位为最佳点 ,而测定远轴面气孔导度时 ,应以叶中。

Leaf stomatal conductance measured and analysed in the canopies of two winter wheat varieties in the field revealed that the probability of adaxial to abaxial conductance ratio followed an approximately normal distribution with a peake value of about 1.5.The ratio changed with the developmental stages being maximium at the heading stage.Leaf stomata in wheat of the upper part of the canopy were more active and showed more pronounced diurnal change of conductance than those of the lower part.Stomatal conductance decreased from top to bottom in canopy as a negative exponential function.By comparing adaxial and abaxial conductances in the apical,middle and basal parts of a leaf,the distribution of the stomatal conductances of a wheat leaf was as follows: a steady decrease from the basal part of adaxial,through the middle and apical parts of the adaxial surface turning to the apical part of abaxial,and then the middle and lastly,the basal part of abaxial.Based on values of the correlation coefficients among the various stomatal conductance and average stomatal conductance,the authors suggested that optimal apical measurement of stomatal conductance would be at the middle and apical parts and that of abaxial would be at middle and basal parts.