effect of foliar application of chitosan on growth and biochemical characteristics of safflower (carthamus tinctorius l.) under water deficit stress

in order to study the effects of water deficit stress and foliar application of chitosan in safflower (carthamus tinctorius l.), a pot experiment was conducted in 2009. experimental design was a randomized complete block in factorial arrangement with three replications. experimental factors were water deficit levels (unstressed (control) and 70% available water depletion from soil (water deficit stress), chitosan concentrations (0, 0.05, 0.1%, all dissolved in 1% acetic acid) along with an additional treatment of distilled water and foliar application times (before and during stem elongation). the results showed that water deficit stress reduced plant height, leaf area, shoot and root dry weight, root height and volume. whereas, foliar application of chitosan increased mentioned traits. in addition, water deficit stress decreased chlorophyll fluorescence, chlorophyll concentration and relative water content. carotenoid, proline and malondialdehyde (mda) content were increased in response to stress. foliar application of chitosan increased chlorophyll fluorescence, relative water content (68.77%) and chlorophyll b in the water deficit stressed plants, whereas decreased mda content. the results of the present study indicate that application of chitosan can reduce the harmful effects of water deficit and improve plant growth.