滴灌湿润比对成龄库尔勒香梨树根系分布的影响

Effects of Wetted Percentage on the Root Redistribution of Mature Korla Fragrant Pear Trees under Drip Irrigation

在充分灌溉条件下采用3种滴灌湿润比（20%、40%、60%）,以漫灌为对照,研究库尔勒成龄香梨吸水根（根直径≤1 mm）在0－70 cm土层内分布的变化,探讨滴灌湿润比对根系分布的影响。结果表明,漫灌成龄库尔勒香梨树吸水根水平方向上在距树体1－2 m内从树行由内向外呈递增趋势;垂直方向上根系随深度呈递增趋势。滴灌对成龄库尔勒香梨树根系分布具有显著的影响：水平方向上吸水根有向滴灌湿润区集中的趋势,并且湿润体内的根系密度随滴灌湿润比增大而递增;非湿润体内,吸水根系数量减少,根系密度随滴灌湿润比增大呈递减趋势。垂直方向,滴灌湿润区吸水根有向20－40 cm土层集中的趋势,其中湿润比20%趋势最明显,湿润比60%次之,湿润比40%影响最小。成龄库尔勒香梨在由漫灌改为地表滴灌初期,滴灌湿润比采用40%较合适。研究结果对库尔勒成龄香梨滴灌系统的设计和管理具有一定的指导意义。

The wetted percentage was an important parameter for drip irrigation design,for the purposes of improving water use efficiency while maintain normal tree growth.The distribution of fine roots（diameter≤1 mm） of mature Kolra fragrant pear trees as affected by wetted percentage was investigated is studied under sufficient drip irrigation.The soil samples were taken from different soil layers to get root samples.The wetted percentages included 3 levels as 20%,40% and 60% with flood as control.The results showed that,under flood irrigation,the fine roots increases with the distance from tree trunk within 1 to 2 m.In the vertical direction,the density of fine roots increased progressively with soil depth,with highest root density of 2.9 mm/cm3 at 40-70 cm soil layer.Compared with that under flood irrigation（the control）,the fine root distribution under drip irrigation treatments was readjusted.In the horizontal direction,the more fine roots were found in wetted zone under the drippers.This showed the absorption of roots to soil water.This indicates more water absorbed from the wetted zones which can reduce deep percolation of water and evaporation so as to improve water use efficiency.In the vertical direction,the fine roots concentrated in the 20 to 40 cm soil layer.Most obvious readjustment of root distribution was found under 20% treatment,followed by those under 60% and 40%.In conclusion,at the initial stage when the irrigation of mature Kolra fragrant pear trees is shifted from flood irrigation to drip irrigation in arid area,the wetted percent of 40% is more appropriate.The results had a certain significance to guide the drip irrigation system design and management for mature Kolar fragrant pear.