Crescimento e desempenho produtivo de cultivares de soja em diferentes épocas de semeadura no Centro-Sul do Estado do Paraná

Abstract

The study objectived to evaluate the growth and yield performance of four soybean cultivars (FPS Urano RR, BMX Apolo RR, BMX Energia RR and BRS 284), sowed at three dates (October 21st, November 18th and December 20th, 2010), in Mid-South of Parana State. The experimental design was a randomized block with three replications, in a split-plot arrangement, being the sowing dates allocated to plots and the cultivars to subplots. At R8 growth stage, it was realized the harveste and seed yield and its components, as well as morphological parameters important to ensure the yield, were analyzed. During growth development, plants were sampled at growth stages: V4, V9, R2 and R5.3, analyzing its biometrical characteristics and the plants physiological parameters. The cultivar BRS 284 had highest number of seeds per area, but the lowest mass of 100 seeds. The mass of 100 seeds decreased with the sowing delay, except to the cultivar BRS 284. The seed yield decreased with the sowing delay in the cultivars that had reduction in the 100 seeds mass. The cultivar BMX Energia RR was the best option for the early sowing obtaining the highest seed mass and yield and the cultivar BRS 284 showed to be a good option for late sowing. It was found reduction of plant growth in all cultivars with delaying sowing dates, however, the cultivar FPS Urano RR showed the lowest difference in the final plants morphology among the different sowing dates. The definition of the final morphology of the plants occurred after the phenological stage V9. Leaf area index at R5.3 was the morphological character with highest correlation with final plant seed yield. The delay of sowing date resulted in higher net assimilation rate, but smaller crop growth rate than early sowing date. The cultivar BMX Energia RR showed the highest seed filling rate and harvest index at all dates of sowing, being more efficient than the others cultivars.