Salt Stress Relief and Growth-Promoting Effect of Sweet Pepper Plants (Capsicum annuum L.) by Glutathione, Selenium, and Humic Acid Application

Abstract

Three pot experiments were carried out at a private farm in Abu Homos, El-Beheira Governorate during 2018 and 2019 and 2020 growing seasons to examine the role of Glutathione, Selenium, and Humic Acid solely in the first two seasons and in combinations in the third season in elevation the impact of salinity on vegetative growth (leaves fresh weight, leaves dry weight and leaf area), chemical composition (chlorophyll, N, P, Ca, K, Na, Proline contents, K/Na ratio) and yield of sweet pepper cultivar "Madrid". The results illustrated that the growth parameters, chemical composition and yield of sweet pepper decreased by increasing salinity level. The results of the mitigation treatments of Glutathione, Selenium, and Humic acid, showed that the application of either Selenium alone in the first two seasons or combined with Glutathione in the third season showed significant effects for increasing plant growth, nutrient contents and yield under the highest salinity level.

Mitigation of Environmental Stress-Impacts in Plants: Role of Sole and Combinatory Exogenous Application of Glutathione

“…They can be categorized into 7 main groups: protein hydrolysates and N-containing compounds, botanical extracts, inorganic compounds, humic and fulvic acids, biopolymers, beneficial fungi and bacteria ( du Jardin, 2015 ). Among the seven types of biostimulants, four of them from the groups, protein hydrolysates and N-containing compounds, botanical extracts, inorganic compounds, humic and fulvic acids, were combined with GSH to investigate their combined effects on plants in response to abiotic stresses such as salinity and metal toxicity ( Dawood et al, 2020 ; Elkhatib et al, 2021 ; Jahan et al, 2021 ; Rehman et al, 2021 ). A brief introduction and key results of the combined application of GSH and biostimulants were elaborated in the subsections below.…”

“…Among the elements, the role of Se in alleviating stress-induced damage through activation of the antioxidant defense system in plants has been explored and studied ( Chu et al, 2010 ; Jiang et al, 2017 ). These studies demonstrated the significance of Se as an antioxidant and a cofactor of the enzyme GPX, catalyzing the reduction of H 2 O 2 , which is overproduced when the plants are under stress ( Elkhatib et al, 2021 ). Besides that, Se can control the permeability and changes in activities in a plant cellular membrane ( Dawood et al, 2020 ).…”

“…Humic substances such as humic and fulvic acid are plant and animal decomposed matter, formed by biochemical transformation and microbial metabolism, found readily in soils, which represents the central pool of organic carbon on the surface of the earth ( Mackowiak et al, 2001 ; Canellas et al, 2015 ). Humic acids (HA) are humus materials that are aqueous-alkaline soluble and have been proposed as a sustainable alternative to alleviate salinity stress and improve plant crop productivity ( Elkhatib et al, 2021 ). Previous studies have proved the significance of HA application in stimulating plant growth through the increase in root length, development of secondary shoots and higher uptake of nutrients.…”

“…Previous studies have proved the significance of HA application in stimulating plant growth through the increase in root length, development of secondary shoots and higher uptake of nutrients. HA can also permanently tie up Na + and Cl − ions, increase plant membrane permeability and promote uptake of macronutrients like N, P, K, Ca, and Mg, which alleviates the ionic and osmotic stress induced by salinity stress ( Mackowiak et al, 2001 ; Canellas et al, 2015 ; Elkhatib et al, 2021 ). Recently, Elkhatib et al (2021) evaluated the effects of exogenous GSH, Se and HA individually and combined them as paired treatments (GSH + Se, Se + HA, and GSH + HA) on sweet pepper plants ( Capsicum annuum L.) grown under salinity stress.…”

“…HA can also permanently tie up Na + and Cl − ions, increase plant membrane permeability and promote uptake of macronutrients like N, P, K, Ca, and Mg, which alleviates the ionic and osmotic stress induced by salinity stress ( Mackowiak et al, 2001 ; Canellas et al, 2015 ; Elkhatib et al, 2021 ). Recently, Elkhatib et al (2021) evaluated the effects of exogenous GSH, Se and HA individually and combined them as paired treatments (GSH + Se, Se + HA, and GSH + HA) on sweet pepper plants ( Capsicum annuum L.) grown under salinity stress. All treatments individual or paired resulted in a significant improvement in vegetative growth and yield in plants under salinity stress, which was correlated to the increase in total chlorophyll, decrease in Na + uptake, increase in nutrient uptake such as N, P and Ca .…”