Impacts of plant arrangement and nitrogen fertilization in the agronomic performance of grain sorghum

Abstract

New plant arrangements have proven to be beneficial for soybean cultivation. However, little is known about the performance of sorghum in these arrangements when grown in succession, particularly associated with nitrogen topdressing. Thus, the objective of this study was to evaluate the agronomic performance of grain sorghum grown in double rows and its response to nitrogen topdressing. Two experiments were conducted in the field in the Southwest of the State of Goiás, Brazil. In both, a 2x2 factorial randomized block design was adopted with six replications, corresponding to two row spacings (traditional - 0.50 m and double rows - 0.25x0.75 m) and the use or not of 90 kg ha^-1 N as urea in topdressing. The grain sorghum hybrid used was Buster, and plant height, stem diameter, panicle length, shoot dry mass, thousand grain weight, and yield were evaluated. Double-row spacing did not change plant height or thousand-grain weight compared with traditional spacing. However, traditional spacing provided a higher grain yield than the double row spacing at both locations, with increases of 21% in Rio Verde (905 kg ha^-1) and 40% in Montividiu (1.879 kg ha^-1). The response of grain sorghum to nitrogen topdressing was variable in relation to the environment, with a 16% increase in grain yield in Rio Verde, without any influence from the plant arrangement.