evaluation of the effect of sargassum angustifolium extract on growth and yield indices of lactuca sativa under drought stress conditions

Lettuce (lactuca sativa) represents a major horticultural crop in iran and worldwide. lettuce requires a high amount of water to grow well and is adversely affected by drought. regarding the reports of the positive effect of seaweed extract on increasing the resistance of plants to abiotic stresses, the present study aimed to evaluate the effect of the seaweed sargassum angustifolium extract on growth and yield indices of lettuce under drought stress. this study was conducted as a factorial experiment with three treatments of algae extracts concentrations and two treatments of drought stress, and non-stress treatment with three replications. to evaluate the effects of algae extract on lettuce under drought stress conditions, a combination of morphological and physiological characteristics including plant height and dry weight, photosynthetic pigment content, and antioxidant activities were measured. results showed that treatment of seaweed extract significantly increased plant resistance to drought stress and improved morphological and physiological indices of lettuce (p< 0.05). the best results were obtained in the 1.5 g/l treatment of seaweed extract.