Desenvolvimento e produtividade da cultura do milho sob densidades de plantas e espaçamentos entre linhas simples e duplas

Abstract

In the last years, maize (Zea mays) has received great valuation by the farmers from a mere culture intended for the program of crop rotation, to an agricultural commodity. Among the main factors that have been influencing the increase of planted area and crop progress are the use of most productive materials, better plant arrangement from the used cultivar, reduction of space between lines and / or increasing population density. In this context, this study aims to assess the development and productivity of maize under plant densities and spacings between single and double lines. The experiment was conducted in the city of São João, PR on private property. The experimental design was a randomized complete block design with four replications in bifactorial scheme 5 x 5, consisting in five row widths (double rows: 0,4 x 0,2; 0,5 x 0,2; 0,6 x, 0,2; 0,7 x 0,2 m and single row width to be the control: 0,7 m) and five plant densities (50.000; 65.000; 80.000; 95.000; 110.000 plants ha-1).The experimental units were composed of four rows of 5 meters length, with the usable area composed of the two central rows by 3 meters long. At V12 stage the characters plant height and stem diameter were evaluated. At R5 stage were evaluated height of plants, stem diameter, insertion height of first ear, ears index and final plants population. The yield components evaluated were ear length, number of seed rows per ear, 1000 seeds weight and yield. The harvest was made manually, the seeds were processed by a stationary threshing. Productivity data were corrected with index to 13% of moisture. Data were tabulated and submitted to analysis of variance to assess the effects of the factors row widths and plant densities and their interaction using the Genes software. To evaluate the effects of double row spacings and the contrast between double rows and the control (Single Row), the means were compared by “T” test at 5% probability. When the interaction between the double row spacings and plant population was significant, the data were analyzed on the surface response. The increase in population density promoted reduction in stem diameter, the ears index, number of rows per ear, ear length and productivity. The space between lines significantly influenced the plant height, insertion height of first ear and productivity, where higher results were found in single spacing. Independent of plant population used the spike index and stem diameter were higher in double line spacing. Grain yield responded negatively linearly to the increase of density, indicating that the hybrid SUPERIS has poor adaptability to high populations.