The objective of this research was to evaluate effects of chitosan on morphological and physiological characteristics of safflower (Carthamus tinctorius L.) under water deficit stress conditions. For this purpose, a pot experiment was conducted with three factors including water deficit levels (unstressed and 70% available water depletion from soil (water deficit stress)), chitosan concentrations along with an additional treatment of distilled water and foliar chitosan application times (before and during stem elongation). Results showed that water deficit significantly decreased plant height, leaf area, shoot and root dry weight, relative water content (RWC) and chlorophyll whereas increased carotenoid, soluble carbohydrates content, malondialdehyde (MDA) and proline content. The foliar chitosan application time effect was significant only for proline content. Spraying with chitosan during stem elongation increased prolin content. In stressed plants, application of chitosan (0.05 and 0.1%) increased plant height, leaf area, shoot and root dry weight, relative water content (RWC), chlorophyll and soluble carbohydrates content. Chitosan significantly increased growth and chlorophyll content in the leaves developed on grapevine plants grown under water stress conditions [1]. Application of chitosan also increased accumulation of soluble sugar in water stressed rice plants [2]. MDA content was significantly lower in the stressed plants sprayed with chitosan (0.5 and.01%) compared with the control plants. These results showed that chitosan alleviated the harmful effects of water stress and increased the tolerance of plants to stress by increasing osmolytes accumulation and therefore could be used to improve crops in water stress conditions.
