Produtos químicos utilizados no tratamento de sementes no desenvolvimento da soja inoculada com Bradyrhizobium

Abstract

One of the great challenges in the soybean crop nowadays is to increase production without the need of adding new areas of crops. In this aspect the seeds treatment stands out. In the present study, it was aimed to evaluate the effect of chemical treatment, applied in two seasons, in soybean seeds inoculated with Bradyrhizobium japonicum, in the nodulation of the roots of plants in vegetative performance, productivity and on the physiological quality of the seeds produced. Seeds of the cultivar SYN 13671 IPRO (GMR: 7.3) and NS 7000 Ipro (GMR: 6.7) were used, treated with four combinations of chemicals (Standak® Top, Cruiser® 350 FS + Maxim® XL, CropStar® + Derosal Plus® and the Control) applied at two different times (30 days before and on the day of sowing). On the day of seeding, inoculation was performed, with inoculant type liquid containing bacteria Bradyrhizobium japonicum strains (SEMIA 5079 and SEMIA 5080) with and without adhesive fixatives. Sowing was carried out in the field and 15 days after, the stand was counted. At full flowering (R1/R2) the following were measured: number of nodules, dry matter of nodules, chlorophyll content and nitrogen content. On the day of harvest the following were evaluated: plant height, height of the first pod, number of pods and seeds per plant, weight of a thousand seeds, grain yield and grain size. For the experiment in greenhouse conducted in pots type Leonard the same treatments and the experiment was conducted until the plants reach the phenological stage R1/R2 were carried out, in which the following were evaluated: plant height, SPAD index, dry weight of aerial part, number and dry mass of nodules. The seeds originated from the field experiment were harvested and stored in cold chamber and were subsequently made the following analyzes: germination test, tetrazolium test (force, feasibility and damages by bugs), electrical conductivity test, accelerated aging and seedling emergence test, first count, emergence and dry mass of aerial part). The treatments tested did not affect the productivity of cultivars, which may be applied with 30 days in advance or on the day of seeding. In spite of changes in the number and weight of nodules, the treatments did not affect the biological nitrogen fixation, evaluated by the leaf nitrogen and chlorophyll content. In a greenhouse, the treatments did not affect the nodulation as well as the biological nitrogen fixation, because they do not affect the number and dry mass of nodules and the content of total chlorophyll. In laboratory tests and seedbed, the seed physiological quality (germination and vigor - accelerated aging, electrical conductivity, end, dry matter of plants) are not affected when seeds of parents are treated with the products tested, and also the treatment may be performed 30 days before or on the day of seeding.