title: Impacts of Priming with Silicon on the Growth and Tolerance of Maize Plants to Alkaline Stress.
abstract: Silicon (Si) has been known to augment plant defense against biotic and abiotic pressures. Maize (Zea maize L.) is classified as a Si accumulator and is relatively susceptible to alkaline stress. In this study, seeds of maize were grown in pots and exposed to various concentrations of Na2CO3 (0, 25, 50, and 75 mM) with or without 1.5 mM Si in the form of sodium metasilicate Na2O3Si.5H2O for 25 days. Alkaline-stressed plants showed a decrease in growth parameters, leaf relative water content (LRWC), and the contents of photosynthetic pigments, soluble sugars, total phenols and potassium ion (K(+)), as well as potassium/sodium ion (K(+)/Na(+)) ratio. By contrast, alkaline stress increased the contents of soluble proteins, total free amino acids, proline, Na(+) and malondialdehyde (MDA), as well as the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in stressed plants. On the other hand, application of Si by seed-priming improved growth of stressed plants, which was accompanied by the enhancement in LRWC, and levels of photosynthetic pigments, soluble sugars, soluble proteins, total free amino acids and K(+), as well as activities of SOD, CAT, and POD enzymes. Furthermore, Si supplement resulted in a decrease in the contents of proline, MDA and Na(+), which together with enhanced K(+) level led to a favorable adjustment of K(+)/Na(+) ratio, in stressed plants relative to plants treated with alkaline stress alone. Taken together, these results indicate that Si plays a pivotal role in alleviating the negative effects of alkaline stress on maize growth by improving water status, enhancing photosynthetic pigments, accumulating osmoprotectants rather than proline, activating the antioxidant machinery, and maintaining the balance of K(+)/Na(+) ratio. Thus, our findings demonstrate that seed-priming with Si is an efficient strategy that can be used to boost tolerance of maize plants to alkaline stress.
authors.affiliation: Botany Department, Faculty of Science, South Valley UniversityQena, Egypt; Biology Department, College of Applied Medical Science, Taif UniversityTaif, Saudi Arabia.
authors.forename: Arafat A
authors.initials: AA
authors.lastname: Abdel Latef
authors.affiliation: Plant Abiotic Stress Research Group & Faculty of Applied Sciences, Ton Duc Thang UniversityHo Chi Minh City, Vietnam; Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource ScienceYokohama, Japan.
authors.forename: Lam-Son P
authors.initials: LS
authors.lastname: Tran
keywords: alkaline stress; antioxidant enzymes; leaf pigments; maize; osmoprotectants; seed-priming with Si; stress mitigation