XVI International Botanical Congess

Two field experiments with datura plants were conducted during 1996 and 1997 seasons to study the effect of Jasmonic acid at three levels, i.e., 200, 400 and 800 ppm, besides the distilled water as a control on growth, physiological characteristics, endogenous hormones and yoeld. The obtained results showed that JA application at different levels significantly decreased plant height. Number of both leaves and branches as wella s dry weights of the different parts of the plant were increased by JA treatments. Plants sprayed with JA showed a decreased in transpiration rate and total chlorophyll. JA application decreased growth promoters and increased growth inhibitors with the increase in JA levels. Seed yield and alkaloids as well as oil content in seeds were significantly increased by JA treatments.