亏缺灌溉对成龄库尔勒香梨产量与根系生长的影响

研究了亏缺灌溉对成龄库尔勒香梨树营养生长、果实生长与吸收根系分布的影响。香梨的生育中期,设计了4种土壤水分亏缺(灌前土壤水势下限):轻度胁迫(-100 kPa)、中度胁迫(-200 kPa)、重度胁迫(-300 kPa)和对照(-50 kPa)。灌溉系统为地表滴灌。试验结果表明,亏缺灌溉显著地减少了夏季剪枝量,提高了果实产量。充分灌溉条件下,香梨树根长密度从树行由内向外呈递减趋势,滴灌促进了湿润体内的吸收根系的发育;距树行0.5 m,根长密度随着深度的增加而减少;距树行1 m至1.5 m,根长密度随着深度的增加而增加;距树行2 m的非灌溉区,根长密度在垂直方向上变化不显著。为适应滴灌湿润体内水分胁迫,香梨树在湿润体内及非灌溉区的吸收根系的分布均发生了显著的调整。适度水分胁迫下的根长密度增加对香梨产量有促进作用。

Yield and Root Growth of Mature Korla Fragrant Pear Tree under Deficit Irrigation

The experiment included four levels of the soil water deficit (threshold of soil water potential before irrigation) applied in the middle period of fragrant pear growth: slight (-100kPa), moderate (-200kPa),severe (-300kPa) water stress and the control (-50kPa). The irrigation system was surface drip irrigation. The results indicated that the water stress irrigation significantly reduced the summer pruning weight, improved the yield. Under full irrigation, the root length density (RLD) decreased with the increment of distance from the tree row, and root development in the wetted zone of drip irrigated pear tree was enhanced. The RLD at 0.5m from the tree row decreased with the depth; however, the RLD in the range from 1m to 1.5m from the tree row increased with the depth; in the non-irrigated zone at 2m from the tree row, the differences of RLD among the depths were not obvious. The RLD in the wetted and non-irrigated zone adjusted significantly due to the water stress in the wetted zone, as compared to the control. Increase of RLD due to the moderate soil water deficit showed some positive effects to the yield improvement.