玉米生育期土壤-植物-大气连续体水流阻力与水势的分布

根据玉米生育期的田间试验资料分析了土壤-植物-大气连续体中水势和水流阻力的分布,结果表明土壤与植物叶片之间的水势差在玉米抽雄期前达0.8—1.0MPa,到抽雄期以后达1.0—1.5MPa,叶片与大气之间的水势差则在抽雄期前后分别达80—120MPa和60—80MPa;连续体内的水流阻力主要在叶片与大气之间.建立了连续体中玉米叶片水势的动态模拟公式,模拟叶水势具有较高的精度.最后,揭示了叶片蒸腾速率与叶-气系统水势差和水流阻力的关系,当叶片与大气之间的水势差达90—100MPa之后,蒸腾速率随叶-气间水势差增加而减小.

Distribution of hydraulic resistance and water potential in soil-plant-atmosphere continuum during growing period of maize

Based on the data measured in maize field, the distribution patterns of hydraulic resistance and water potential in soil-plant-atmosphere-continuum (SPAC) are analysed. The difference of water potential between soil and maize leaf is about 0. 8-1.0 and 1.0—1.5MPa before and after heading stage,and the corresponding value between leaf and atmosphere is respectively 80-120 and 60—80MPa. The hydraulic resistance in SPACis mainly existed between leaf and atmosphere. Adynamic simulation model of maize leaf water potential is established,and the simulated leaf water potential is in good agreement on measured data. This paper also reveals the relationship of leaf transpiration rate with water potential difference between leaf and atmosphere and hydraulic resistance. When the water potential difference between leaf and atmosphere is larger than. 90—100MPa, the leaf transpiration rate is decreased with increasing water potential difference.