Abstract: To provide the theoretical basis on apple cultivation, some indicators of drought resistance,yield and fruit quality of red Fuji apple were studied after apple leaveswere sprayed with different concentration of natural brassinolide. The experiment was set up as a completely randomized block design with twelve replicates. The research results showed that the relative water content and critical saturation deficit were increased. Natural saturation deficit, the degree of water requirement, the rate of transp iration, cell membrane permeability and injury rate were decreased compared with control. Natural brassinolide reduced water loss of apple leaves and enhanced its drought resistance. The results also indicated that natural brassinolide improved the growth of apple leaves, restrained the growth of shoot in autumn, and increased fruit set and yield of apple without reducing apple quality.

Key words: Natural brassinolide, Apple, Drought resistance, Fruit yield