Desenvolvimento e produtividade de milho híbrido em diferentes densidades de plantas e épocas de cultivo

Abstract

The hybrid corn introduced on the market today have foliar architecture modified by genetic improvement. They have more erect leaves and are suitable for greater densification, which increases the efficiency of the natural resources, especially solar radiation. In this context, the objective of this research was to evaluate the vegetative development and performance components of the hybrid corn AG 7088 RR2, cultivated at different plant densities and under dry or irrigated conditions in the Roraima savannah. The experiments were carried out in the agricultural years of 2016 (irrigated crop) and 2017 (dry crop), at the experimental field of the “Centro de Ciências Agrárias” (CCA) of the “Universidade Federal do Roraima” (UFRR). The experimental design was a randomized complete block design with six treatments and four replications. The treatments consisted of six planting densities: 40; 60; 80; 100; 120 and 140 thousand plants ha-1. At 70 days after sowing (DAS), the variables related to vegetative development were evaluated, and at 120 DAS the production components were analyzed. Of all the analyzed variables, only the height of the flag leaf and the total height of the plant were not affected by the different planting densities. The elevation of planting density linearly increased the attenuation of the photosynthetically active radiation at the middle third and lower third of the plants canopy. With the increase of plant density, there was a linear reduction in all variables related to the corn cob. The density of maximum yield estimated in the irrigated crop was 123,511 plants ha-1, corresponding to the maximum yield of 10,855.7 kg ha-1, and in the dry crop the maximum density estimated was 126,960 plants ha-1, with maximum estimated productivity of 10,315.6 kg ha-1.