Physiological, biochemical and nutritional roles of magnesium on nitrogen biological fixation in soybean genotypes

• Grant number: 18/11136-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2018
• End date: August 31, 2019
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: André Rodrigues dos Reis
• Grantee: Roberto Casetta Alves da Cruz
• Host Institution: Faculdade de Ciências e Engenharia. Universidade Estadual Paulista (UNESP). Campus de Tupã. Tupã , SP, Brazil

Abstract

Magnesium (Mg) participate in the chlorophyll molecule and shows essential physiological roles as enzymatic activator of rubisco. Magnesium is considered as a forgotten element due to very scarcy information about the physiological and nutritional roles in plants. Modern soybean varieties has been shown low protein concentration in the seeds. Despite the non nitrogen fertilization in the soybean crop due to the symbiosis with Rhizobium, this study hypothesise that plant showing optimal levels of Mg show higher chlorophyll concentration, therefore, accumulate more photosynthetic compounds like sucrose and total sugar. Our hypothesis is that plants well nourished with Mg show more photosynthetic rates and higher fluxes of sugar in the cell. We assume that part of produced sugar is transported via phloem to the nodule (where are located the bacteria responsible for the nitrogen biological fixation). The higher sugar concentration in the nodule might increase the ureide synthesis (allantoin and allantoic acid), which are the main nitrogen compounds in soybean plants. This study aimed to evaluate the levels of Mg in soybean genotypes. The nitrogen compounds (ureides, aminoacids, nitrate and ammonium), sucrose, total sugars, photosynthetic pigments (chlorophyll, pheophityn, and carotenoids), oxidative metabolism (lipid peroxidation and hydrogen peroxide concentration), and antioxidative enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase), and nutritional analysis will be performed durig the an thesis phonological stage of soybean plants. Storage proteins (albumin, globulin, prolamin, and glutelin), sugars, aminoacids and nutritional analysis will be performed in the seeds. The role of Mg in the physiology and yield of soybean plants is barely understood and there are lack of information in the literature. This study will provide powerful information regarding the role of Mg on the nitrogen biological fixation in soyben plants. This information will be useful for further recommendation of optimal Mg doses to be applied for soybean plants aiming to increase the nitrogen biological fixation, wich can increase the soybean yield. (AU)