Effect of drought stress and polymer on osmotic adjustment and photosynthetic pigments of sunflower

Abstract

Water stress affects plant growth and crop productivity in the vast semi-arid and arid regions of Iran. The present study was aimed at investigating the effect of drought stress and super absorbent polymer (SAP) on the osmotic adjustment and carotenoid content of sunflower (cv. Master) under field condition. The experiment was carried out as a split plot based on randomized complete block design with three replications. Three irrigation levels (irrigation after 6, 10 and 14 days) and five amount of super absorbent polymer (SAP) (0, 75, 150, 225, 300 kg/ha) were set as main and sub factors, respectively. Polymer was added in fourteen leaves stage of sunflower to soil in deepness of roots development (by mixing with soil) and at this same stage drought stress was applied.The results showed that effect of different rates of super absorbent polymer and water stress in all traits were significant (P<0.001) as well as their interactive effect of two mentioned factors were significant (P <0.001).Drought stress significantly increased carotenoid content. Drought stress caused an increase in the concentration of soluble sugar and proline content in the leaves of sunflower. These results indicated that lowest amount in proline and soluble sugars accumulation were achieved at 300 kg ha-1 polymer compared with the control (without polymer) in all rates of water even under drought stress conditions.Our results showed that SAP can absorb and retain extremely large amounts of water, so protects the plants against drought.