O FORMATO DAS SEMENTES PODE INFLUENCIAR A PLANTABILIDADE DO MILHO EM DOSADORES PNEUMÁTICOS?

Abstract

The maize crop (Zea mays L.) is of great importance for the Brazilian agribusiness, and has consolidated levels of mechanization in all the productive stages. Within the context of evaluation of sowing quality, there are still obstacles regarding the relationship between seed physical characteristics and deposition technologies. The objective of this work was to evaluate the influence of corn seed format on the longitudinal distribution with the use of pneumatic seed dosing technology. The present research was carried on the Agricultural and forestry Machinery research (NEMPA), in to São Paulo State University (UNESP), Botucatu-SP. A bench simulator used was equipped with a pneumatic action meter, consisting of seed conveyors, motors and frequency inverters for rotation control and speed variation of the systems. Seeds of three maize hybrids with different dimensional characteristics were used. It was evaluated the length, width and thickness of 200 seeds and according to specific methodology the sphericity index was obtained. The experimental design was the completely randomized (DIC), totaling 15 treatments, composed of the three corn varieties, submitted to five vacuum pressures 3, 4, 5, 6 and 7 kPa, with four replications. The simulator worked a constant speed of 6 km.h-1 for all vacuum pressures and a population of 5 seeds per meter was established in the pneumatic doser. The hybrid V1 presented a predominantly oblong shape with sphericity of 61.71% and classified in a C2M type sieve. The hybrid V2 had a mean sphericity of 71.59% and a medium C2M sieve and the hybrid V3 had the highest sphericity index corresponding to 74.13%, with spherical shape and passed through 18C sieve. Concluded that only the sphericity parameter does not allow the decision on the performance of the seed in the dosing mechanism. Among the most important quantitative characteristics for the corn seeds analyzed, the seed width was relevant in the evaluation of deposition quality. For the hybrid V3-18C the pressure of 7 kPa allowed a better result in the longitudinal distribution. For the hybrid V1- C2M the pressure of 4 kPa provided better distributions, whereas for the hybrid V2-C2M the pressure of 3 kPa showed better results. For the pneumatic dosing system the hybrid V3-18C presented the best results of acceptable spacings.