Desempenho agronômico do milho em função de épocas de semeadura na segunda safra e manejo da adubação nitrogenada em cobertura

Abstract

The objective of this work was to study the effect of sowing times and nitrogen fertilization management on maize hybrids in the second harvest. For this, 5 experiments with different sowing times were implemented in two localities of the state of Minas Gerais, three in Chaparral Ashidani Farm, in the city of São João Del Rei and two in Pedra Branca Farm, Luminárias. In each experiment three hybrids (K9110PRO, NS90PRO and 2A401PW) were evaluated in different forms of cover fertilization. At the Chaparral Ashidani farm the application of controlled release fertilizer, Polyblen 40-00-00, dosage 200 kg.ha-1 and the control without application of nitrogen fertilizer were evaluated. In Pedra Branca the control was evaluated without fertilizer application, and the treatments with controlled release fertilization, Polyblen 40-00-00, dosage 200 kg.ha-1 and with urea 46% N NBPT dosage 200 kg.ha-1. The experimental design was in randomized blocks with five replicates, triple factorial, plots constituted by four rows of four meters, being considered the two central lines as useful area. The evaluated traits were: grain yield (kg.ha-1), plant height (m) and first cob insertion height (m). The data were submitted to the individual analysis by locality and joint considering the different environments, through the statistical program R. From the average data obtained for each characteristic evaluated in the 6 environments of each locality, considering sites, times and fertilizations, a graph with 6 half-axes for each hybrid, each of the half-axes representing one of the six environments. It was concluded that the controlled release nitrogen fertilization with Polyblen was not superior to the conventional ones in terms of grain yield responses. Among the evaluated hybrids, the hybrid NS90PRO is worth mentioning, due to its grain yield and stability in the tested environments.