Efeito de dosadores e velocidades de semeadura sobre a uniformidade de distribuição de sementes de soja

Abstract

This research aim was to evaluate the influence of two types of seed metering discs at different sowing speeds on the soybean seed distribution uniformity. The study was made in a rural property in Pato Branco city, Paraná state, using a randomized block design in a 2 x 4 factorial system with four replications. The seed metering discs evaluated were the double-row disc with 90 holes and the single-row disc with 45 holes. The four sowing speeds used were 4.0 km h−1, 6.0 km h−1, 8.0 km h−1, and 10.0 km h−1. The seeder-fertilizer used was a Kunh® PDM PG 700 model with seven rows and 0.5-meter row spacing, and honeycombed seed metering discs. The experiment used soybean seeds BMX Zeus IPRO cultivar. The trials were performed on a 20-meter sand track to make spacing measurement and seed visualization easier. In each test repetition, the seeds were collected after passing through the metering device to evaluate mechanical damage. The following evaluations were performed: acceptable spacings percentage, double spacings, missing spacings, average spacing among seeds, standard deviation, and variation coefficient. The data were submitted for analysis of variance when significant differences (p≤0.05) were presented. For each type of seed metering disc, the means were compared by Tukey’s test (p≤0.05). Related to the sowing speed, a polynomial regression analysis was performed. Mechanical damage on soybean seeds was not affected by the seeding process with the two types of seed metering discs or sowing speed. Increasing the sowing speed resulted in a higher percentage of double missing spacings, standard deviation, and variation coefficient, and a decrease in the acceptable spacings percentage. The seed metering disc with 90 holes increased the average spacing between seeds compared to the mean. For sowing speeds up to 6.0 km h−1, the 45-hole metering device showed satisfactory results. Above this speed, the 90-hole metering disc performed better.