Doses de fertilizante fosfatado revestido no desenvolvimento da soja com diferentes hábitos de crescimento

Abstract

The polymer-coated fertilizers exhibit gradual release of the nutrients, which are available during the cycle plants. The present work aims to evaluate the effects of doses of phosphate fertilizer coated with polymers in the development of the soybean crop in the region of the Middle-North of the state of Mato Grosso. The experiment was conducted in a 2-year no-tillage system, located in the municipality of Sinop-MT, in the agricultural year 2015. The design was DIC, with four replications, with two replications (M8210 IPRO and NS7901 RR) and four doses of coated phosphate fertilizer [0; 60; 120; 180 kg ha-1 of P2O5] and an additional treatment (fertilizer of the producer 90 kg ha-1 of P2O5 in the form of simple superphosphate). The dry mass (DM) of the aerial part, the number of pods (NV), mass of one thousand grain (MMG), accumulation of phosphorus in the aerial part (AP) and productivity were evaluated. The data were submitted to analysis of variance by the F test and applied a test of means to compare the fertilizer doses and submitted to the polynomial regression analysis (p <0.05). The dry mass (DM) of the aerial part was influenced only by the doses and the cultivars. The cultivar NS7901 RR was superior to M8210 IPRO with values of 31.97 and 23.64 g plant-1 . The cultivar M8210 IPRO presented behavior in relation to the doses, with maximum efficiency in the dose of 134 kg P2O5 with 27.25 g dry mass plant-1 . The cultivar NS7901 RR exhibited a linear adjustment resulting in maximum dry mass production (36g plant-1 ) at the dose of 180 kg P2O5. The highest number of pods for NS7901 RR was 64.94 pods with 236 kg ha-1 of P2O5, but for the cultivar M8210 IPRO the highest number of pods was obtained with the dose of 180 kg ha-1 totaling 44.25 pods. The mass of one thousand grains was influenced only by the cultivar, whose average of 144,02g of the cultivar NS7901 RR was superior to 134,87g presented by the IPRO M8210. The accumulation of P in the aerial part of the soybean plants was influenced by the doses and the cultivars, being adjusted polynomial models for both. Equations: NS7901 = 0.22575x + 42.91 (R² = 0.96 **) and IPRO M8210 = 0.15897x + 27.18 (R² = 0.87 **). For the productivity of the cultivar M8210 IPRO the model Y = 5,1741x + 2624,33 (R² = 0.99**) was adjusted. The highest productivity was obtained with the dose of 180 kg ha-1 of P2O5 with 3553 kg ha-1 . For the cultivar NS7901, the best fit equation was Y = -0.04537x² + 17.01114x + 2595.666 (R² = 0.99**). For this cultivar, the maximum yield equivalent to 4,189 kg ha-1 was obtained with the dose of 187.34 kg ha-1.