Nitrogen, sulfur and boron effects in the mineral nutrition of sesame

Abstract

Sesame (Sesamum indicum L.) has experienced substantial growth in national agricultural production. This growth is attributed to its adaptability across diverse cropping systems, high economic value, and the versatility of its derived products. These qualities enable sesame to serve multiple market segments. Despite this expansion, essential information regarding crop management remains scarce. A particular lack exists in fertilization strategies and the balanced provision of macro- and micronutrients. This study was designed to investigate the interaction between nitrogen (N) and sulfur (S) through varying application rates. It also evaluated the effects of different boron (B) rates and sources on sesame cultivation. Two independent experiments were conducted: one under field conditions and another in a greenhouse. These corresponded to the first and second chapters of the thesis, respectively. The field experiment was conducted over two growing seasons (February–June 2023 and December 2023–April 2024) at the Center for Technology Transfer and Development (CDTT) of the Federal University of Lavras (UFLA) in Ijaci, Minas Gerais, Brazil. A randomized complete block design with a split-plot arrangement was employed. Four N rates (0, 60, 80, and 100 kg ha-¹) were used in the main plots, and four S rates (0, 20, 40, and 60 kg ha-¹) in the subplots, each with four replications. The sesame cultivar BRS Anahí was utilized. The parameters evaluated included plant height, number of capsules, grain yield, seed oil content, and nutrient concentrations in diagnostic leaves and grains. The second experiment was conducted in a greenhouse at the Department of Soil Science (UFLA). It utilized a completely randomized design in a 2 × 4 + 1 factorial arrangement with four replications. Treatments included two B sources (ulexite and boric acid), four B rates (2, 4, 6, and 8 mg kg-¹), and a control without B application. The K3 cultivar was used. Assessed variables comprised growth parameters, grain yield, boron concentrations in leaves and grains, and biochemical analyses of grains for protein, amino acid, and sugar contents. In the first experiment, no significant interaction between N and S was detected for the measured parameters. However, more pronounced responses were observed in the second growing season. In the second experiment, B rates and sources significantly influenced the evaluated parameters. The control treatment outperformed the fertilized treatments. These results indicate that sesame responds to fertilization. However, under previously established soil fertility, the crop can develop adequately even with reduced nutrient inputs.