Abstract: 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.

Key words: Soil-plant-atmosphere continuum, Water potential, Hydraulic resistance, Stomata, Transpiration, Maize, DCCA, environmental interpretation., TWINSPAN, plant community