Influence of foliar application with elemental sulfur on onion hybrids

In Brazil, onion cultivation is expanding to other regions of the country, especially to the Northeast, where it has been achieving high productivity. Sulfur is one of the most essential macronutrients for improving the qualitative attributes of onion bulbs. Studies on the appropriate developmental stage for foliar fertilization with elemental sulfur in onion hybrids are scarce, particularly in the Cerrado regions. To evaluate the foliar application of sulfur in onion hybrids, the experiment was conducted using a randomized block design in a factorial scheme. The first factor was the use of four hybrids: Diamantina® F1, Optima® F1, Serena® F1, and Gamay® F1 (purple), and the second factor was the developmental stage at which elemental sulfur was applied via foliar spraying: 4 to 6 leaves, 6 to 8 leaves, 8 to 10 leaves, and 10 to 12 leaves, along with a control that did not receive sulfur. The following characteristics were evaluated: average number of leaves (NUMF), average mass of commercial bulbs (MMBC in g), yield (PROD in t ha⁻¹), and bulb classification (%). The hybrids Serena® F1 and Gamay® F1 showed superior performance in all evaluations. Foliar sulfur applications in onion cultivation favored the predominance of bulb classes 3, 3C, and 4 these being the classes of greatest commercial interest.