FOLIAR APPLICATION OF MAGNESIUM AND BORON IN SUGARCANE GROWN IN POTASSIUM-SATURATED SOIL: PHYSIOLOGICAL EFFICIENCY AND RAW MATERIAL QUALITY

• Grant number: 25/05521-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2026
• End date: December 31, 2027
• Field of knowledge: Agronomical Sciences - Agronomy
• Principal Investigator: Carlos Alexandre Costa Crusciol
• Grantee: Maria Gabriela de Oliveira Andrade
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

In Brazil, the expansion of sugarcane (Saccharum spp.) into more restrictive environments has impacted the crop's average yield. The reuse of by-products from the industrial process as fertilizers, such as vinasse, is one of the many strategies to increase stalk productivity. However, vinasse application can reduce the total recoverable sugar (TRS) concentration in the industry. In this context, foliar applications of magnesium (Mg) and boron (B), applied either in advance or during the maturation phase, have been used with the physiological purpose of inducing the plant to synthesize and transport more sucrose to the stalks, thereby increasing TRS concentration and sugar yield. However, the few studies addressing this topic in the literature were conducted in greenhouse conditions or on different crops, making it difficult to establish a scientific basis for this management practice in sugarcane.Thus, this study aims to evaluate the effect of foliar application of Mg and B on physiological, metabolic, and nutritional parameters and their implications for biometric, technological, and productivity variables of stalks and sugar at different application times and in areas with or without vinasse use. For this purpose, two experiments will be conducted over two consecutive harvests in commercial fields belonging to Usina Santa Cruz, part of the São Martinho Group, located in the municipality of Araraquara (SP). The experimental design will be a randomized block with ten treatments and four replications, including treatments in areas with and without vinasse application. The treatments will consist of the isolated or combined application of Mg and B at three different times: 60, 45, and 30 days before harvest, plus a control treatment.The evaluations will include nutritional status, photosynthetic parameters (gas exchange and activities of Rubisco and PEPCase), carbohydrate and soluble sugar concentrations, photosynthetic pigments and relative chlorophyll index, lipid peroxidation (malondialdehyde and hydrogen peroxide), antioxidant enzyme activity (superoxide dismutase, catalase, and peroxidase), as well as biometric, technological parameters and the productivity of stalks and sugar. The results are expected to provide insights into the best application timing and determine whether foliar application of these elements significantly increases TRS, particularly in areas with vinasse use. (AU)