Efeito do selênio na fixação biológica de nitrogênio no feijão-caupi

Abstract

Cowpea (Vigna unguiculata [L.] Walp.) is a legume of great socioeconomic importance in Brazil, especially in the North and Northeast regions. Biological nitrogen fixation (BNF) reduces the need for nitrogen fertilizers, promoting agricultural sustainability. Selenium, although not essential for plants, can positively influence plant metabolism, enhancing nodulation, photosynthesis, and nitrogen accumulation. This study evaluated the impact of selenium, at doses (0, 0.5, 1.0, and 2.0 mg Se kg⁻¹) and forms (selenate and selenite), on the growth and BNF of cowpea. The experiment was conducted in a greenhouse at the Federal Institute of Piauí (IFPI), Uruçuí Campus, in a completely randomized design with four replications. Parameters such as plant height, shoot and root dry mass, total and viable nodule number, and nodule dry mass were analyzed. Data were subjected to variance analysis, and means were compared using the Scott-Knott test (p<0.05). Selenate, at moderate doses (0.5 to 1.0 mg Se kg⁻¹), showed greater efficiency in promoting growth and nodulation, while selenite had limited effects, reducing nodulation at higher doses. The application of selenium in the form of selenate resulted in maximum nodulation of cowpea at the dose of 1.0 mg Se kg⁻¹. Selenium enhances nodulation and should be considered in the crop’s nutritional management to increase BNF efficiency, contributing to more sustainable and productive agricultural practices with lower environmental impact and reduced costs in systems with low chemical input use