[Objective]The aim was to study the response mechanism of drought stress of wheat varieties in different drought-resistance species,and protect the effection of exogenous NO on oxidative damage and photosynthetic apparatus of wheat leaves under drought stress.[Method]Using low-resistance Yumai 949 and high-resistance Xiamai 5 as test materials,drought stress was carried out to seedlings in five-leaf stage with 15% PEG-6 000,and then NO(0.75 mmol/L SNP,sodium nitroprusside,exogenous NO donor)was used for reg...