Assessment of Seed Priming With Melatonin to Improve Morpho-Physiological and Biochemical Aspects of Common Bean (Phaseolus vulgaris L.) Under Magnesium Deficiency.

Abstract

Magnesium deficiency is a major nutritional constraint that limits the growth and yield of crops and has not generated the necessary attention. In addition, the solution commonly proposed to solve the nutritional problems of crops was using chemical fertilizers. In contrast, other approaches that are more practical, quick to apply, less expensive, and have no impact on the environment and human health are now proposed. Accordingly, we have placed a primary emphasis on the common bean response to magnesium deficiency (Mg-D), with particular attention to the genotypic differences (using two cultivars: coco blanc [CB] and coco nain [CN]), and the use of melatonin (Mlt) as a seed priming agent to identify some traits of tolerance and assess the value of Mlt as a biostimulant of plant tolerance to Mg deficiency. The experiment was conducted hydroponically in a greenhouse, with a factorial completely randomized design. Obtained results showed specific Mg chlorosis in mature leaves more severe and precocious in CB than CN. Mg-D significantly hindered chlorophyll pigments, SPAD index, shoot and root biomass, Mg content, maximum quantum yield of PSII (Fv/Fm), and the photochemically converted energy fraction in PSII (YII). The photochemical quenching (qP) and electron transfer rate (ETR) decreased also, against an increase in nonphotochemical quenching (qNP). Seed priming with Mlt efficiently alleviated these multiple effects, and CN responded better to Mlt treatment. CN is more tolerant than CB due to its better management of Mg nutrition and the related Mg-dependent functions. Melatonin significantly improves the tolerance of common bean to Mg deficiency through an efficient management of energy in the electron transfer chain.