苹果幼树根域局部灌溉的水分运转特性

【目的】研究部分根域灌水条件下，水分在根系和地上部的运输及根系间的横向运输。【方法】以三年生分根盆栽的‘皇家嘎拉’苹果幼树为试材，采用氘水（HDO）示踪法，研究部分根域灌水后不同时间段水分在苹果树根系、主干、一年生枝、当年生新梢与叶片的运输和分配特点及灌水、干旱根域间根系的水分运输差异。【结果】1/4根域灌溉处理HDO最高丰度首先出现在根系中，然后是地上部各个器官；而2/4根域灌溉的HDO最高丰度在地下根系和地上部器官同时出现，但时间较1/4根域灌溉处理推迟；288 h的根系HDO丰度始终高于地上部各器官。1/4、2/4根域氘水处理后2 h，根系中HDO丰度百分比均呈现出吸收根＜2-5 mm＜2 mm＜大于5 mm根的顺序，地上部以叶片和主干HDO丰度较高。【结论】部分根域水分供应不足时，根系首先吸收水分满足自身需求，然后再向地上部运输；部分根域水分供应充足时，根系吸收的水分同时向地上部和其它根域根系运输。灌水根域向干旱根域的水分运输主要通过直径>5 mm根、2-5 mm根、<2 mm根和吸收根逐级完成。

Characteristics of Water Transportation for Apple Trees Submitted by Partial Root-Zone Irrigation

【Objective】Water transportation between root and shoot,and root to root und partial root-zone irrigation was investigated in this study.【Method】Potted three-year old ’Royal Gala’ apple trees were used to investigate characteristics of water transportation and distribution in root and organs of shoot,as well as water transportation in root of irrigated root-zones and drought root-zones at different time points after partial root-zone irrigated by deuterated water(HDO).【Result】The highest abundance of HDO for treatment in 1/4 root-zone irrigation was firstly found in the root,and then in different organs of shoot,however,the highest HDO abundance for treatment of 2/4 root-zone irrigation was simultaneously found in the root and shoot,but the time was postponed in comparison to treatment of 1/4 root-zone irrigation.HDO abundance in root for 288 hours was higher than that in organs of shoot all the time.After 1/4 and 2/4 root-zones were irrigated by HDO for 2 hours,the percentages of HDO abundance in the root demonstrated a sequence of absorbing root<2-5 mm root <2 mm root< roots with a diameter more than 5 mm,and the highest HDO abundance for organs of shoot was found in leaves and trunk.【Conclusion】The results showed that water absorbed by root firstly satisfy its own demand,and then were transported to shoot when water supply was insufficient,otherwise,water was transported to root and shoot at the same time.It is preliminarily assumed that water transportation from irrigated root-zones to drought root-zones is realized mainly in turn by roots of diameter more than 5 mm,roots between 2-5 mm,roots with a diameter less than 2 mm and the absorbing roots.