Effects of drought stress on photosynthesis, its parameters and relative water content of anise (Pimpinella anisum L.)

Drought is a major environmental stress that affects plant morphology, physiology and biochemistry, causing a significant reduction in agricultural production. In order to study the effect of drought stress on physiological traits of anise (Pimpinella anisum L. (a field experiment was conducted at College of Agriculture, University of Zanjan during spring of 2010. The experiment was conducted as a complete randomized block design with three replications. In this study the effect of water stress in three levels, irrigation at all stages of a weekly (control), excision irrigation in the mid-flowering stage to indication signs of stress to 15 days and then re- irrigation, and excision irrigation in grain filling stages to indication signs of stress to 15 days and then re- irrigation were studied. Chlorophyll content index (CCI), assimilation rate, stomatal conductance, transpiration rate and relative water content (RWC) significantly (p 0/05) decreased under drought stress conditions but leaf temperature increased.