The effect of drought stress and super absorbent polymer (A200) on agronomical traits of sunflower (Helianthus annuus L.) under field condition

In many areas of Iran, the reproductive growth stage of sunflower is exposed to the drought stress. Therefore, the investigation of irrigation management in the farm was necessary for increasing irrigation efficiency and decreasing water loss. The objective of the present study was to investigate the effect of different amounts of super absorbent polymer (A200) and levels of drought stress on morphological characteristics, such as: head diameter, stem diameter, plant height, 100-seed weight, seed yield and physiological characteristics, such as: relative water content (RWC), chlorophyll concentration of sunflower (cv. Master) under farm conditions. The experiment was carried out as a split plot based on randomized complete block design with three replicates. Three irrigation levels (irrigation after 6, 10 and 14 days) and five amounts of super absorbent polymer (0, 75, 150, 225 and 300 kg/ha) were set as main and sub-factors, respectively. Polymer was added at the fourteen leaf stage of sunflower to soil in deepness of root development. At this same stage, drought stress was applied. Polynomial models of each traits based on the ANOVA were fitted. The results indicated that drought stress has decreased significantly all the measured traits. In this study, seed yield has shown a significant decrease. After 6 days, irrigation has resulted in higher yields than other irrigation intervals. The highest seed yield was related to 300 kg/ha polymer application and the lowest one was related to irrigation after 14 days with no application of polymer. Regarding the limitation of water resources, super absorbent polymer could be a useful strategy for the sustainability of yield under drought stress in sunflower

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

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