Plantabilidade de milho em função de velocidades de semeadura e pressões de vácuo do dosador de sementes

Abstract

Among corn crop management, plantability is a determining factor in obtaining an adequate plant stand. Thus, the objective of this work is to evaluate corn plantability parameters when sown at different working speeds and vacuum pressures of the dosing mechanism. The work was conducted on a private property located in the municipality of Vitorino, southwest of Paraná, in a randomized block experimental design (DBA), with four replications, in a 2 x 4 factorial scheme, with two sowing speeds (4.0 and 8.0 km h-1) and four seed doser vacuum pressure levels (7; 11; 15 and 19 inches of water – in.H2O), equivalent to 0.25; 0.40; 0.54 and 0.69 PSI. A John Deere® seeder-fertilizer, model Series 1100, equipped with a John Deere® pneumatic seed meterer was used. The Agroeste 1844® hybrid was used, aiming for a population density of 74,000 plants ha-1. Initially, seeds from the respective treatments were collected to assess mechanical damage using the tetrazolium test (0.075%). The tests were carried out on a sand track measuring 30.00 meters long by 1.00 meters wide and 0.08 meters thick. After sowing, the percentage of acceptable spacings (EA - %), of double spacings (ED - %), of failed spacings (EF - %), the average spacing between corn seeds (EM – cm), and the standard deviation (DP) and the coefficient of variation (CV - %). The data were subjected to analysis of variance in case of significant interaction (p≤0.05), the average seeding speeds were compared using the Tukey test (p≤0.05), while for the vacuum pressure factor it was polynomial regression analysis was adopted, with the models selected based on the criterion of highest R2 and significance (p≤0.05) of the equation parameters. The decrease in vacuum pressure caused a reduction in double spacings and an increase in failed spacings, due to the difficulty in retaining the seeds in the disc alveoli, and when worked with 17 in.H2O at 4,0 Km h-1, it resulted in better occurrence of spacings acceptable and 16.11 in. H2O pressure for speed 8,0 km h-1. Also, at both speeds, when working with 15 in.H2O pressure, lower DP, CV and gap gaps were obtained. The increase in seeding speed resulted in an increase in DP, CV, double spacing and mechanical damage. The decrease in speed provided an increase in acceptable spacings and a decrease in failed spacings and as the vacuum pressure increased, it resulted in an increase in the occurrence of mechanical damage.