COMPARATIVE STUDIES BETWEEN SEAWEEDS AND COMMERCIAL ALGAE IN ALLEVIATION OF HARMFUL EFFECTS OF DROUGHT STRESS OF FABA BEAN (VICIA FABA L.) PLANTS

Abstract

The effect of seaweed extract (SWE) obtained from two macroalgae species (Sargassum latifolium and Corallina elongate) and two commercial algae (Canada power and oligo x) on drought stress tolerance in faba bean (Vicia faba L.) plants was studied. Examination of growth parameters and some physiological and biochemical parameters showed that SWE extract and commercial algae under stress conditions enhanced shoot length and decreased root length, in most cases, at stages 1&2 in faba bean plants with comparison to stress conditions. All treatments, mostly, caused decreases in fresh and dry weight of faba bean plants under drought stress. Maximal increases in shoot and root lengths were observed in stress case in presence sargassum extracts in comparison to drought stress. Number of leaves, flowers and yield parameters decreased in response to drought. Bio stimulant especially sargassum extract caused increasing in these parameters. In most cases, Chl.a, Chl.b, Chl. a+b and carotenoids of leaves of faba bean plants increased at stage 1 and decreased at stage 2 as a result of all treatments. Carbohydrate and protein contents of root, shoot and seed yield showed increases under stress of faba bean plants. Amylase and protease activities revealed different responses to all treatments. With respect to antioxidant enzymes, peroxidase activity of faba bean plants at both stages of growth increased in response to all treatments, with exceptions of stress + sargassum and stress + Canada power at stage1. In case of activities of super oxide dismutase and poly phenol oxidase showed decreases at both stages of growth with comparison to stress conditions, with exception of super oxide dismutase at stag 2 of faba bean plants. Total phenolic content was increased in faba bean plants under different treatments (with exception of treatment with stress + Canada power) with respect to stress conditions. Acidic growth hormones, IAA, GA3 and ABA exhibited increases in GA3 contents of faba bean plants as a result to all treatments as comparison to stress condition, however IAA and ABA contents decreased, with exception of treatment with stress + sargassum extract in case of ABA. The increased total phenolic content and the enhancement of antioxidant enzymatic activity by SWE and commercial algae in stressed faba bean plants may contribute to protection against peroxidation and reduce the severity of water deficit.