夏玉米农田SPAC系统水分传输势能及其变化规律研究

试验测定华北平原夏玉米农田SPAC系统不同界面的水势,并计算水流传输阻力结果表明,大气水势和叶水势均呈明显日变化,最大值出现在日出前;大气水势日变幅最大,土壤水势主要受土壤含水量的影响而日变化较平缓。夏玉米植株由下部至上部呈逐渐降低的水势梯度,水流在SPAC系统传输过程中不同界面间存在明显的水势梯度和较大的阻力,从叶片至大气的阻力远大于由土壤至叶片的传输阻力,证明从叶片至大气阻力对限制与调节作物水分散失强度和数量具有关键作用。

The changing of water transfer potential in soil-plant-atmosphere continuum system of maize field

By measuring the water potential of fixed points and sites in different interfaces of the SPAC system of maize field in North China Plain,the resistance of water transferring is calculated.The results show that atmospheric water potential and leaf water potential have obvious daily variation.The maximum water potential appears before sun rising; the daily atmospheric water potential changes violently,and the soil water potential changes relatively little,mainly under the influence of the soil water content.There exists a grade of water potential that gradually decreases up forward within the plant of summer maize,In the course of water transmission in SPAC system,different interfaces show obvious grades of water potential and great resistance.The resistance from leaf to atmosphere is much more than that from soil to leaf,implying that the resistance of leaf-atmosphere plays a key role in the restriction and adjustment of the dissipations rate and quantity of water from plants.