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.