Second-crop corn in the State of Paraná

The second-crop corn has become one of the main agricultural production systems in Brazil, with the state of Paraná being one of the largest national producers of this crop. The expansion of the soybean-corn system has significantly contributed to increased grain production and the strengthening of animal protein production chains, playing a strategic role in the state and national economy. However, second-crop corn cultivation is subject to several factors that limit productivity, notably abiotic stresses such as water deficit, low temperatures, frosts, and irregular rainfall distribution, as well as biotic factors such as the corn leafhopper (Dalbulus maidis), the corn stunt complex, foliar diseases, insect pests, and weeds. These factors directly affect the physiological and biochemical processes of the plant, compromising the growth, development, and yield of cultivated hybrids. In this context, genetic improvement plays a fundamental role in the development of cultivars better adapted to the edaphoclimatic conditions of Paraná. The use of modern tools, such as marker-assisted selection, genomic selection, high-precision phenotyping, digital agriculture, remote sensing, and gene editing, has contributed to accelerating the development of more productive, resistant, and stable hybrids. Furthermore, the integration of breeding technologies, agronomic management, and climate monitoring represents a promising strategy to minimize the impacts of climate change and increase the sustainability of the production system. Therefore, this review gathers and discusses the main aspects related to the cultivation of second-crop maize in the state of Paraná, addressing the factors that influence productivity, the physiological and genetic mechanisms of resistance, the technological advances applied to genetic improvement, and the prospects for the development of more resilient and efficient production systems.