It has been reported that resistances of scions to biotic and abiotic stresses are improved by grafting.For example, resistances to some foliar fungal diseases such as powdery mildews are improved in grafted scions when certain rootstocks were used;however, the mechanism to improve these resistances is still unclear.We hypothesized that water stress during acclimatization phase of grafting may improve the resistances of scion through morphological responses.