Hydraulic conductivity and water-use efficiency of young pear tree under alternate drip irrigation

To investigate the effect of alternate drip irrigation on hydraulic conductivity and water-use efficiency of young pear tree, a field experiment was conducted with three drip irrigation methods, i.e. alternate drip irrigation (AD!, both sides of the root-zone irrigated alternatively), fixed drip irrigation (FDI, only one side of the root-zone irrigated), conventional drip irrigation (CDI, watering near the base of tree), and three irrigation levels, i.e. irrigation quantity of 20 (W1), 30 (W2) and 40 mm (W3), respectively. Results show that compared to CDI, ADI reduced total hydraulic conductivity (root to leaf), soil evaporation, evapotranspiration, leaf area and total dry mass of young pear tree, but increased water-use efficiency (WUEET) and irrigation water-use efficiency (WUEI) when the watering was reduced by 50% at W1, and it reduced soil evaporation, evapotranspiration, leaf area and total dry mass, but increased total hydraulic conductivity (root to leaf), WUEET and WUEI when the watering was reduced by 25-33% at W2 and W3. However, FDI significantly decreased total hydraulic conductivity and total dry mass when compared to CDI. Thus ADI significantly increased total hydraulic conductivity due to its more evenly watering to the whole root-zone, which led to the increase of water-use efficiency when the watering was reduced by 25-33%. (C) 2012 Elsevier B.V. All rights reserved.