调亏灌溉和灌溉方式对香梨树吸收根系重分布的影响

Effect of Regulated Deficit Irrigation and Irrigation Mode on Fine Roots Redistribution of Fragrant Pear Trees

于2009—2010年开展了田间试验,研究了调亏灌溉对成龄库尔勒香梨树吸收根系重分布的影响。灌溉方式为地表滴灌与漫灌,滴灌试验包括轻度与重度水分胁迫处理(在新梢及果实生长缓慢期分别按蒸发量的60%与40%灌溉,在其他生育期按蒸发量的80%灌溉),对照处理为充分灌溉,在整个生育期按蒸发量的80%灌溉。每年4—8月份,漫灌每月灌溉1次,灌水定额为300 mm。所有处理在2009年之前均为漫灌。研究结果表明,成龄库尔勒香梨树的吸收根系主要分布于地表以下20~60 cm。梨树需要2 a时间调整吸收根系的分布以适应灌溉方式由漫灌转为滴灌。土壤水分胁迫减小了梨树吸收根系的根长,抑制了梨树的营养生长,其后恢复充分灌溉可促进根系的生长。梨树新梢及果实生长缓慢期的土壤水分胁迫对根系生长的抑制效果超过了对新梢生长的抑制;但吸收根系的生长与果实产量之间并无显著的相关性。

Field experiment was conducted to evaluate the effects of regulated deficit irrigation on the fine roots redistribution of mature Korla fragrant pear trees planted in the oasis in 2009 and 2010. The experiment consisted of drip and flood irrigation plots. The drip irrigation plots included two water deficit treatments： applying 60% （moderate） and 40% （severe） of pan evaporation during the slow growth stage of both shoot and fruit （ stage 2） , and 80% （full irrigation） of pan evaporation in the two other stages, and the control treatment： applying 80% of pan evaporation during the whole growth season. The flood irrigation plots were irrigated with amount of 300 mm per month from April to August. All the experimental plots were flood irrigated before 2009. The results showed that fine roots of mature Korla fragrant pear trees mainly distributed in 20 - 60 cm soil layers. The previously flood irrigated Korla fragrant pear trees spent two years on adapting to the irrigation mode transformation from flood irrigation to drip irrigation through redistributing their fine roots. Water stresses decreased fine roots length and inhibited the vegetative growth of fragrant pear trees, while the resumption of full irrigation boosted their growth. The water deficit inhibited fine roots development more effectively than shoots, owing to the near cessation of shoot growth in stage 2. However, no remarkable correlations between fine roots length and fruit yield were observed. The results provided the theoretical basics for regulated deficit irrigation application to the mature fruit trees planted in the extremely arid regions.