In order to analyse the physiological and biochemical mechanisms of bitter melon powdery mildew,four bitter melon strains with different resistance to powdery mildew were chosen as materials,the changes of some physiological and biochemical indexes in leaves were studied after seedlings of bitter melon were infected by powdery mildew.The results showed that the chlorophyll and soluble protein mass fraction presented a rise at first and followed by a decline,soluble sugar mass fraction showed a tendency of d...