effect of water deficit stress on soluble sugars, proline, protein and chlorophyll content in sunflower (helianthus annuus l.) hybrids

mechanisms of tolerance to water deficiency stress for introducing sunflower hybrid was investigated by a two-factor experiment as a split plot design based on rcbd was at the research station in alborz province, hashtgerd region, iran in 2013. irrigation rates (irrigation after 50, 100 and 150 mm cumulative evaporation from class a evaporation pan) were considered in the main plots and sunflower hybrids (farokh, allstar, ghasem, hysun 25) as sub plots. in this study, the amount of soluble sugars, proline, protein, chlorophyll content, oil content and yield, protein yield and some agronomic characteristics were determined. based on the results, the amount of total soluble sugars, proline and chlorophyll-b contents as mechanisms to resist water deficit stress significantly increased with increased water deficit stress. allstar hybrid had the highest amount of total soluble sugars (176.05 mg/g f. w), proline (45.43 mg/lit) and chlorophyll-b (12.52 mg/g f. w). also, allstar produced the highest grain yield and oil content in both mean water deficit stress conditions with values 2121 and 956.90 kg/ha, and in severe water deficit stress condition with values 829 and 315.10 kg/ha, respectively. however, with normal irrigation, farokh hybrid had highest grain yield and oil yield.