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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... 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. 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 space variations of soil moisture and sample contents are decisive factors to the error ranges and accuracies of the determination. With the statistic analysis of different soil water content rates in samples with the content of 15, the variation characteristics of different soil water content rates at 1 m soil layer are obtained.And the relationship between the sample content, and the measurement accuracy requirement and characteristic value is found out. Also this paper points out that... The space variations of soil moisture and sample contents are decisive factors to the error ranges and accuracies of the determination. With the statistic analysis of different soil water content rates in samples with the content of 15, the variation characteristics of different soil water content rates at 1 m soil layer are obtained.And the relationship between the sample content, and the measurement accuracy requirement and characteristic value is found out. Also this paper points out that limited numbers of sample contents can't meet the accuracy requirements in research. In general, at least 5~8 sample contents can possibly keep the relative error of the measurement under 5%~10%. 土壤湿度空间变异性和样本容量决定了其测定的误差范围和精度。通过样本容量各为15的各层次土壤含水率的统计分析,得到了1m土层各层次的土壤含水率的变异特征。找出了样本容量与测试精度要求及统计特征值的关系。指出,过少的样本容量无法达到研究所需的精度要求。一般最少要5~8个以上的样本容量方可将测试的相对误差控制在5%~10%以下。 The results obtained by the determination of humus composition and the determination of elemental composition,optical density, distribution of molecular weight and thermal properties of humic acids in lateritic red earth,lateritic red earth in orange plantation and vegetable soil developed on the lateritic red earth indicated that the mellowness of lateritic red rarth through dry farming was favorable not only to the formation of humic acid but... The results obtained by the determination of humus composition and the determination of elemental composition,optical density, distribution of molecular weight and thermal properties of humic acids in lateritic red earth,lateritic red earth in orange plantation and vegetable soil developed on the lateritic red earth indicated that the mellowness of lateritic red rarth through dry farming was favorable not only to the formation of humic acid but also to the improvement of aromaticity and the increase of molecular weight.The thermal properties of humic acid,to certain extent,reflected its structural variation characteristics. 对赤红壤以及发育其上的果园赤红壤、菜园土的腐殖质组成和胡敏酸的元素组成、光密度、相对分子质量分布及热性质等的测定结果表明,赤红壤经旱耕熟化后,不但有利于胡敏酸的形成,而且胡敏酸的芳香族比重提高,相对分子质量增大.胡敏酸的热性质在一定程度上也反映了其在土壤熟化过程中结构变化特征.
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