大豆近轴和远轴叶面特征与其高度避日性取向的生理意义

大豆远轴叶面具有高密度的茸毛和气孔及大量连片状蜡质。小叶两而气孔对水分亏缺和光强变化的反应有差异。严重水分胁迫下，大豆末端小叶在中午呈高度避日态—对缺水不敏感、对强光敏感的远轴叶面气孔向光，除增大反射显著降低叶温外，还遮盖了一侧生小叶，极显著减缓了三出复叶木质部水势的下降，并且维持了较高的叶片净光合

Adaxial and Abaxial Characters in Relation to Physiological Significance of Advanced Paraheliotropic Orientation of Soybean Leaflets

The abaxial epidermis had high pubescence density and great stomata frequency and a waxy bloom. The responses of adaxial and abaxial stomata to water status and light intensity were different. The complete inverted (advanced parahelitropism) terminal leaflets at midday under severe water stress, which abaxial stomata that were more sensitive to increasing light intensity and less sensitive to declining xylem water potential than adaxial stomata became exposed to incoming irradiation, substantially reduced leaflet temperature (P<0. 05)by increasing light reflectance and significantly retarded water loss(P<0. 01)by shading a lateral leaflet, and could maintain a high leaflet net photosynthetic rate. Therefore, advanced parahelitropic orientation is an effective morphological adaptation to water stress.