Densidade agronômica ótima de milho em ambientes de produção

Abstract

To supply the demand for corn by the year 2050, it is necessary to increase 100% of production in the world. The increase in plant density was one of the main factors that promoted the increase in yield at the level of crops in the last 40 years. From 1980 to 2016, there was an increase in density of 24 % and allowed an average increase of 3 Mg.ha-¹. The objective of this study was to determine the optimal agronomic density in production environments. The production environments were classified as low (<10 Mg.ha−¹; Agudo), medium (10 and 16 Mg.ha−¹; Entre-Ijuís and Jóia), and high (> 16 Mg.ha-¹; Júlio de Castilhos) yield. Experiments were conducted in these production environments, located in the state of Rio Grande do Sul (RS), southern Brazil, with densities ranging from 60 to 140 thousand pl.ha-¹. The sowing densities that provided the highest yields were 116.2 thousand pl.ha-¹ and 60 thousand pl.ha-¹ in the high and low yield environment, respectively. The density increase caused increases in yield in the high environment and reduction in the low yield environment. The number of grains per row was the yield component most sensitive to variations in density for the three environments. The density of 120 thousand pl.ha-¹ provided the greatest efficiency in the photosynthetically active radiation intercepted conversion in grains (22.6 kg.ha-¹ per MJ.m-²), on the other hand, the density of 100 thousand pl.ha-¹ intercepted the largest amount of photosynthetically active radiation (89%).Therefore, these results are of great importance in increasing in the resources use efficiency by adjusting the agronomic optimal density, especially in production environments with yields greater than 16 Mg.ha-¹.