不同砧木红星苹果树含水量的日变化呈Ｖ形曲线。以乔砧树最高，Ｍ７中间砧树次之，Ｍ９中间砧树较低。含水量的日变化与水势的日变化基本呈正相关。地上部含水量与砧木解剖构造有关，矮砧树地上部含水量较低是导致树体矮化的因素之一 The diurnal variation of water content of apple trees with different rootstocks showed a V-shaped curve. To Joe anvil tree highest, M7 middle anvil next, M9 middle anvil tree lower. The diurnal variation of water content is positively correlated with the diurnal variation of water potential. The aboveground water content is related to the rootstock anatomy, and the lower water content in the dwarf rootstock is one of the factors leading to dwarfing of the tree