Effect of chitosan on safflower (Carthamus tinctorius L.) Seed Germination and antioxidant enzymes activity under water stress

In order to study the effects of different chitosan concentrations (0، 0. 05، 0. 1، 0. 2، 0. 4، 0. 5، 1، 2، 3%،) along with a additional treatment of distilled water on seed germination of safflower (Carthamus tinctorius L.) seedling، under water stress conditions (0، -4، -8 and -12 bar) an experiment was conducted in a controlled-environment condition. Results showed that germination percentage، germination index، shoot and root height، shoot and root dry weight and protein content decreased with increasing water stress. Proline and malondialdehyde (MDA) content، Catalase (CAT) and peroxidase (POX) activities increased by increasing osmotic potential to -8 bar. The greatest shoot height and dry weight (19. 3 and 36% more than distilled water treatment، respectively) were observed at 0. 4% chitosan concentration. At low concentrations of chitosan (0. 05 - 0. 4%) protein and proline contents and CAT activity increased and MDA content decreased. In osmotic potential -8 bar، the highest germination percentage، shoot and root height obtained by 0. 4% chitosan concentration. Also at this osmotic potential a decline in and MDA proline contents، CAT and POX activity and an increase in the concentrations of protein (in comparison with distilled water treatment) were detected in low concentrations of chitosan. In the highest level of osmotic potential (-12 bar)، germination percentage، shoot and root height increased by low concentrations of chitosan in comparison with distilled water treatment. Also at this osmotic potential the least rate of former parameters obtained by 1-3% chitosan. Thus، it suggests that chitosan concentration at 0. 4% or lower levels may improve germination percentage of safflower seeds and benefit for seedlings growth under water deficit stress.