Eficiência de diferentes formas de aplicação de Bradyryzobium em soja

Abstract

The productivity of the soybean crop in recent years has been growing, thanks to new technologies that are brought into the crop, such as cultivars adapted to the different assertive cultivation, cultural and phytosanitary regions. Techniques such as the use of inoculants, the base of Bradyrizobium japonicum, in the treatment of seeds and in furrow of cultivation have been used, demonstrating increased productivity. Still some producers have been applying the aerial form of Bradyrhizobium in order to supply a deficient nodulation in the initial phase of the crop. However, these different forms of application raise doubts as to their efficiency, the objective of this work being to evaluate different forms of application of Bradyrhizobium in the treatment of seeds, in furrow cultivation and in spraying in the vegetative phase in soybean cultivation. The work was carried out in the experimental area of UTFPR - Campus Dois Vizinhos, during a 2019/2020 harvest. The experimental design was in randomized blocks, in four replications, with plots of 16 m2, being the treatments, application of Bradyrhizobium in the seed, in the cultivation furrow and aerial application 15 days after emergence (DAE). The inoculant used in all treatments was based on Bradyrhizobium japonicum - SEMIA 5079 and 5080, Bacterial concentration: 5x109 CFU/ml (Atmo). Seeds of the cultivar Nidera (NS 5909 IPRO), were treated with the insecticide and fungicides previously (10g/L Metalaxil-M, 25g/L Fludioxonil), and at the time of sowing an inoculation was carried out, at a dose of 3ml/kg of seed (a commercial dose). For the treatment with the use of the inoculant in a furrow, a dose was 400 ml/ha (two commercial doses), with a syrup volume of 60 liters per hectare. For aerial spray treatments, the dose was 800 ml/ha (four commercial doses), with a syrup volume of 200 liters per hectare, carried out in the late afternoon. The evaluations took place 60 days after the DAE emergence, considering the number of nodules and the dry mass of the nodules, and at harvest, plant height, number of pods and branches per plant and productivity. Finally, the results showed that the three forms of inoculation increase the nodulation of soybean plants, however, the greatest efficiency was the use in the furrow, followed by the treatment in the seed and aerial application, respectively. The application in the furrow of cultivation, provided greater increase of nodules, with improvement of the agronomic parameters, effective in gain of productivity.