Phthalimide treatments at 125, 250 and 500 mg 1 -' to female plants of dioecious Morus nigra L. induced intersex and male flowers . Qualitative and quantitative analyses of acid phosphatase in male and female flower buds showed that the male flower had significantly higher levels of the enzyme activity than the female flower buds . The level of acid phosphatase activity significantly increased in intersex and male flowers induced on female plants after phthalimide treatments .