Atributos Biofísicos e População de Plantas de Soja na Validação de Zonas Homogêneas em Área de Produção de Grãos

Abstract

Soybean (Glycine max L. Merrill) is one of the most prominent crops for grain production and cultivated area in Brazil. Its widespread cultivation throughout the country opens doors for the development and use of precision agriculture. In this regard, the so-called homogeneous zones (HZ) can receive personalized management, aiming to extract the maximum productive potential from the crop. The objective of this study was to validate the definition of homogeneous zones in soybean production areas based on the response of the crop's biophysical attributes to different plant populations. The research was conducted in a 48-hectare area at the Glória Experimental Farm of the Federal University of Uberlândia, in Uberlândia-MG. The studied variables included the biophysical attributes of soybean plants, such as height, number of nodes, pods, and weight of a thousand grains, obtained from different population densities. The soil in the study area is classified as Red Latosol, and soybean seeding followed the no-tillage system. The study compared two population densities: the recommended seeding with a population of 300,000 plants per hectare and a population approximately 25% lower than recommended, with 220,000 plants per hectare. In the area, 48 sampling points were defined using the QGIS software. Each point in the sample grid contained two plots with an area of 20 m2, one for each population density. Based on preliminary analyses of the initial plant stand data obtained for each of the 48 points, homogeneous zones (HZ) were defined. Harvesting was carried out in useful areas of 8 m2, with samples taken from ten plants to obtain data on the biophysical attributes of soybeans. Attribute analyses were conducted using the t-test at a 5% significance level, considering the defined homogeneous zones and plant populations. Plant height, number of nodes on the main stem, number of grains per plant, number of pods per plant, and weight of a thousand grains responded to the effects of homogeneous zones and plant population. The definition of homogeneous zones based on the initial soybean plant stand has an influence on the biophysical attributes of soybeans. In the evaluated conditions, it is possible to observe an inverse relationship between the weight of a thousand grains (WTG) and the number of pods and grains per plant when treatments with different plant densities are compared.