控制性分根区交替滴灌对苹果幼树形态特征与根系水分传导的影响

采用固定滴灌(根区一侧固定供水)、控制性分根区交替滴灌(根区两侧交替供水)和常规滴灌(紧贴幼树基部供水)3种灌水方式和3种灌水定额(固定滴灌和交替滴灌均为10、20和30 mm，常规滴灌为20、30和40 mm)，对比研究了控制性分根区交替滴灌对苹果幼树形态特征与根系水分传导的影响.结果表明： 交替滴灌的根区两侧土壤出现反复干湿交替过程，常规滴灌的根区两侧土壤含水率差异不显著.在灌水定额相同时，灌水侧的土壤含水率在3种灌水方式间差异不显著.与常规滴灌和固定滴灌相比，交替滴灌显著增加了苹果幼树的根冠比、壮苗指数和根系水分传导，在30 mm灌水定额处理下，交替滴灌的根冠比分别增加31.6%和47.1%，壮苗指数增加34.2%和53.6%，根系水分传导增加9.0%和11.0%.3种灌水方式下，根干质量和叶面积均与根系水分传导呈显著线性正相关.控制性分根区交替滴灌增强了苹果幼树根系水分传导的补偿效应，促进了根系对水分的吸收利用，有利于干物质向各个器官均衡分配，显著提高了根冠比和壮苗指数.

Effects of controlled alternate partial root-zone drip irrigation on apple seedling morphological characteristics and root hydraulic conductivity

To investigate the effects of alternate partial root-zone drip irrigation (ADI) on the morphological characteristics and root hydraulic conductivity of apple seedlings, three irrigation modes, i.e., fixed partial root-zone drip irrigation (FDI, fixed watering on one side of the seedling root zone), controlled alternate partial root-zone drip irrigation (ADI, alternate watering on both sides of the seedling root zone), and conventional drip irrigation (CDI, watering cling to the seedling base), and three irrigation quotas, i. e., each irrigation amount of FDI and ADI was 10, 20 and 30 mm, and that of CDI was 20, 30 and 40 mm, respectively, were designed. In treatment ADI, the soil moisture content on the both sides of the root zone appeared a repeated alternation of dry and wet process; while in treatment CDI, the soil moisture content had less difference. At the same irrigation quotas, the soil moisture content at the watering sides had no significant difference under the three drip irrigation modes. At irrigation quota 30 mm, the root-shoot ratio, healthy index of seedlings, and root hydraulic conductivity in treatment ADI increased by 31.6% and 47.1%, 34.2% and 53.6%, and 9.0% and 11.0%, respectively, as compared with those in treatments CDI and FDI. The root dry mass and leaf area had a positive linear correlation with root hydraulic conductivity. It was suggested that controlled alternate partial root-zone drip irrigation had obvious compensatory effects on the root hydraulic conductivity of apple seedlings, improved the soil water use by the roots, benefited the equilibrated dry matter allocation in seedling organs, and markedly enhanced the root-shoot ratio and healthy index of the seedlings.