Abscisic acid and brassinolide combined application synergistically enhances drought tolerance and photosynthesis of tall fescue under water stress

•ABA and BR improved the activities of antioxidant system under drought.•BR application compensated photosynthetic loss caused by ABA.•ABA plus BR application colligated their respective effect on improving antioxidant activity.•ABA plus BR application synergistically enhanced the drought tolerance and photosynthesis of tall fescue.