Changes in soil water content in the rhizosphere of Artemisia ordosica: Evidence for hydraulic lift

摘要

Hydraulic lift by Artemisia ordosica was investigated in a greenhouse study. The root system was grown in two soil compartments: a drier, upper soil and a wetter, deep soil. Diurnal soil water content (0v) at 10, 25, and 35 cm in the top pots was measured at 4-h intervals with time domain reflectometry. There was an increase in 0v at all three depths from 22:00 to 05:00 h during the three experiment days. The average amplitudes of fluctuations at 10, 25, and 35cm were 0.0108, 0.0159, and 0.0314m~3m~(-3), respectively. Root distributions in the upper pots were: also investigated. At 0-10 cm, weight density and volume of primary roots were significantly greater than the fine roots, but at 25-35 cm, weight density and volume of fine roots were significantly greater than primary roots. At 10-25 cm, weight density of primary roots was greater than that of fine roots. Changes in values of soil water content (0.01m~3m~(-3)) and root length density, weight density, and volume at 10, 25, and 35 cm in the upper pots indicated a clear linear relationship between the magnitude of hydraulic lift and length density of fine roots (r = 0.999***).