Nodule Formation, Antioxidant Enzymes Activities and Other Biochemical Changes in Salt Stressed Faba Bean Plants Treated with Glycine Betaine, Arbuscular Mycorrhiza Fungi and Yeast Extract

Abstract

To ameliorate the harmful effects of salinity stress on faba bean plants, two pot experiments were conducted in the greenhouse of Agriculture Botany Department, Faculty of Agriculture, Ain Shams Univ., Shoubra El-Kheima, Kalubia Governorate, Cairo, Egypt, during the two successive seasons of 2013/2014 and 2014/2015. Faba bean plants (Vicia faba L. cv. Sakha 1) were irrigated with three levels of NaCl (non-saline (Tap water), 2500 and 4500 ppm). Glycine betaine (GB) at 5 mM, yeast extract (Saccharomyces cerevisiae) at 5 ml/l were applied to plants as foliar application, and arbuscular mycorrhizal fungi (Glomus irradicans (AMF)) inoculation was performed by mixing with the soil at 10% w/w. The obtained results indicated that yeast and AMF as bio-stimulators and GB as osmolytes treatments, improved growth, nodules formation, antioxidant substances concentrations (proline, phyenols) and yield parameters (pod weight and number, seed weight & number and 100-seed weight) as compared with untreated stressed plants. Meanwhile, these treatments reduced membrane permeability (MP) and lipid peroxidation (MDA). Plants treated with GB showed the most vigorous growth measurements (plant height, number of leaves, number of branches, shoot fresh and dry weight) and relative water content (RWC). The same trend was noticed with biochemical concentration in leaves and seeds (e.g. proline, phenols, protein concentrations, antioxidant enzymes (peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO) and ascorbate peroxidase (APX)) activities and yield components followed by plants inoculated with AMF and finally plants treated with yeast extract. Glycine betaine treatment increased chlorophyll concentration followed by mycorrhiza and then yeast treatments under 2500 ppm NaCl but it had limited effect at 4500 ppm NaCl. Meanwhile, plants inoculated with mycorrhiza surpass other treatments in root measurements including root fresh weight, root dry weight and nodules formation. Glycine betaine, mycorrhiza and yeast treatments mitigated the harmful effects of salt stress through the enhancement of the protective parameters in stressed faba bean plants and consequently improved growth and yield characteristics.