Abstract: To provide the theoretical basis on walnut cultivation， the water contents an d the photosynthetic
rate of walnut leaves were studied after the leaves were treated with natural brassinolide． The experiment Was set up
as a randomized complete design th three replicates．The research results showed that after walnut leaves were
sprayed with diferent concentration of natural brassinolide， leaf water content， relative water content， free water
content an d critical saturation deficit were increased． Natural saturation deficit， the degree of water requirement，
the rate of transpiration，cell membrane penetration and injury rate were decreased，and chlorophyl content and
the rate of photosyn thesis were raised．The efect of0．30 mg‘L一 on walnut among the diferent concentrations of
the natural brassinolide Was the most obvious．Compared with control， leaf water content， relative water content，
free water content and critical saturation deficit were increased by 9．6％ ． 16．1％ ，7．9％ and 26．8％ respective．
1v．Th e natural saturation deficit an d the degree of water requirement were reduced by 9．0％ an d 24．5％ ．Th e rate
of transpiration at 1：30 P．m．was cut down by 32．7％ ．The cel membrane penetration and injury rate were
dropped by 2．5％ and 7．1％ ． T0tal chlorophyl content an d the rate of photosyn thesis were increased by 310．3％
an d 444．9％ ．

Key words: Natural brassinolide, Walnut, l_eaves, Water content, The rate of photosyn thesis