The physiological effects of cold hardening,drought hardening and abscisic acid(ABA)spraying on cucumber seedlings were studied,and the mechanism of plant cross-adaptation in stress was investigated. Three seedling treatments all improved the chilling resistance of cucumber seedlings and ABA content.The ABA content was significantly correlated with the chilling resistance. The peroxidase activity was significantly enhanced by cold hardening,and a new band of isoenzyme was found. The new band resulted from t...