摘要
该文用田间遮雨棚下模拟土柱的试验方法，研究了不同水分水平处理下土壤－植物－大气连续体中能量变化和分布规律。结果表明，植物叶片水势既随土壤水势的下降而按直线变化规律递减，也随大气水势而变化，但土壤水势对植物叶片水势的影响要比大气水势的影响大些；在玉米的整个生长过程中，植物叶片水势还表现出先下降阶段后上升阶段的动态变化特性。植物根木质部水势动态变化规律与叶水势的动态变化规律非常相同，植物根木质部水势均大于相对应的叶片水势，两者相差０．２５～０．６０ＭＰ＿ａ。在５个不同水分水平处理中，水分从土壤输送到植物根木质部，其能量降低分别为０．８１～１．４１ＭＰ＿ａ，０．９１～１．５６ＭＰ＿ａ，０．９４～１．６７ＭＰ＿ａ，０．９２～１．６８ＭＰ＿ａ，０．７７～１．８２ＭＰ＿ａ；从植物根木质部到叶部能量损失分别为０．２５～０．５０ＭＰ＿ａ，０．２８～０．５３Ｐ＿ａ，０．３０～０．５７ＭＰ＿ａ，０．３０～０．６０ＭＰ＿ａ，０．３３～０．６７ＭＰ＿ａ；水分从叶部汽化扩散到大气中其能量降低分别为５５．３６～１１１．３０ＭＰ＿ａ，５５．１４～１１１．１４ＭＰ＿ａ，５４．６１～１１１．０４ＭＰ＿ａ，５４．４６～１１０．９７ＭＰ＿ａ。则?
The simulated experiment under rainproof in field was done to study the characteristicsof energy variation and distribution in SPAC in the different treatments of water supply levels.Theresults showed that the leaf water potentoal was linearly decreased with the decrease of the soil wa-ter potential,and it was affected by the pneumatic potential.but the effect of the soil water poten-tial to the leaf water potential was greater than that of the pneumatic potential.During the growthof the crop,the leaf water potential displayed the dynamic variation characteristics of the decreasingstage at first and thd increasing stage at latter. The dynamic feature of the root xylem water poten-tial variation was the same as that of the leaf water potential variation,the root xylem water poten-tial was larger than the corresponding leaf water potential,the difference value was the range of0.25～0.60MP_a. In the five different treatments of water supply levels,the loss of energy of waterfrom soil to root xylem was the range of 0.81～1.41 MP_a,0.91～1.56MP_a,0.94～1.67MP_a,0.92～1.68MP_a,0.77～1.82MP_a,respectively;from roct xylem to leaf was the range of 0.25～0.50MP_a,0.28～0.53MP_a,0.3～0.60MP_a,0.33～0.67MP_a,respectively;and from substomatalcavities to atmosphere was the range of 55 36～111.30MP_a,55.14～111.14MP_a,55.01～111.09MP_a,54.61～111.04MP_a,54.46～110.97MP_a,respectively. Therefore,when water floW-ing in SPAC,the vaporization of water in leaf and the diffusion of water vapor were main positionsof energy transformation and loss,and the main energy loss of liquid water flowing took place in theconnecting “chain”through which water entered the root from soil.
出处
《水土保持学报》
CSCD
北大核心
1994年第3期81-86,共6页
Journal of Soil and Water Conservation
基金
国家自然科学基金
关键词
土壤
植物
大气连续体
叶片水势
soil-plant-atmosphere continuum soil water potential root xylem water potential leaf water potential pneumatic potential
