Caffeic acid pretreatment enhances dehydration tolerance in cucumber seedlings by increasing antioxidant enzyme activity and proline and soluble sugar contents

•Pretreating cucumber with 100μM CA alleviates growth inhibition under dehydration.•Pretreatment with CA enhances levels of proline and soluble sugars under dehydration.•CA application elevates antioxidant enzyme activities in dehydration-stressed leaves.•100μM CA enhances transcript levels of Cu/Zn-SOD, Mn-SOD and GPX under dehydration.•Exogenous CA decreases ROS levels and increases dehydration tolerance of cucumber.