Produtividade de híbridos de milho segunda safra submetidos a doses de nitrogênio

Abstract

Second-season maize production depends directly on proper nitrogen management, especially in environments with low rainfall and strong thermal fluctuations. This study evaluated the productive response of maize cultivars to different nitrogen rates under the edaphoclimatic conditions of Western Paraná. The experiment was conducted in a randomized block design in the experimental area of the Federal University of Technology – Paraná (UTFPR), Santa Helena campus, using two hybrids, P3282 VYH and P4285 VYHR, subjected to increasing nitrogen topdressing rates (0, 60, 90, and 120 kg ha⁻¹). Regression analysis showed that, for the P3282 VYH cultivar, the linear component was significant, indicating a proportional increase in yield with increasing N rates, while the quadratic component was not significant. For the P4285 VYHR cultivar, neither component was significant, although the fitted models exhibited high coefficients of determination, allowing general response trends to be inferred. Average yield increased with nitrogen rates in both hybrids, but with distinct patterns between them. The fitted curves demonstrated greater accuracy in describing the productive response of P3282, mainly due to its significant linear behavior, whereas P4285 showed greater variability due to the lack of statistical significance of the tested components. Phenology also differentiated the hybrids: P3282 reached flowering and grain filling during relatively wetter periods, whereas P4285 went through these stages under pronounced water deficit, influencing its physiological efficiency and final performance. The meteorological conditions observed during the cycle reinforced the advantage of the early-maturing hybrid under drier second-season conditions. The results demonstrate that nitrogen fertilization strategies must consider cultivar cycle, water regime, and the physiological response limits of each genotype in order to enhance nutrient-use efficiency and optimize yield in second-season maize production systems.