トウモロコシ葉の気孔コンダクタンスの変動に関する向軸面と背軸面の比較

Abstract

We compared the variability of stomatal conductance between adaxial and abaxial surfaces of maize leaf in different environmental conditions, and addressed stomatal response to environmental factors, such as soil moisture.The stomatal conductance (G) for each of adaxial (gstd) and abaxial (gstb) surfaces and both surfaces combined (Gst) of a leaf varied significantly during the measurement. Diurnal changes of gstd, gstb and Gst were similar showing either unimodal, bimodal, or fluctuating patterns which depended on the environmental regimes of the measurement days. The gstb was larger than gstd, ratio (α) of gstb to gstd was not constant, the α varied with change in the environmental conditions during the measurement. Meanwhile, the stomatal conductance (gstd) (ZS), gstb (ZS), Gst (ZS) in different leaf positions (ZS, distance from the top of stem) on the stem decreased from upper leaf to lower leaf with quadratic functions, but the ratio of stomatal conductance on the two surfaces (α) in different leaf positions on the stem showed no specific pattern of changes.Effect of soil water content (θS, on mass basis) on the stomatal conductance (G) was expressed as G=GMax(1-θS0/θS), where G represented either gstd, gstb, or Gst; GMax was the maximum of G; θS0 was the soil water content when G=0. The relationships between the daytime average of the ratio α and the average photosynthetic photon flux density, saturation deficit and air temperature were expressed by quadratic functions, but the relationship between the average α and the mean of soil water content on mass basis was linear.