Tratamento antecipado de sementes de soja com fungicida, protetor celular e inoculante

• Autor(a) principal: Sediyama, Camilla Atsumi Zanuncio
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1222
• topic: Glycine max; Sementes; Vigor; Produtividade; Análise trilha; Inoculante; Glycine max; Seeds; Force; Productivity; Track analysis; Inoculant; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The utilization of high vigor seeds in the establishment of a soybean crop is essential for obtaining adequate plant population. In this crop, the biological nitrogen fixation through soybean-Bradyrhizobium symbiosis was a major driving force for large-scale cultivation of this crop in Brazil by replacing the mineral N fertilization and providing a significant reduction of production cost. The inoculation procedure is performed just before the sowing. It is frequently described as an action that reduces the efficiency of sowing operation due to the time expended. In some instances, this difficulty has been responsible for no inoculation by the farmers, with losses in productivity. However, the use of cell protector polymer can be a form of protection during the inoculation of bacteria and also extends the period of survival of bacterial cells between seed treatment and sowing, eliminating the immediate sowing of seeds inoculated. Therefore, the objective of this work was to evaluate number of colony- forming units of bacteria, the germination and vigor of soybean seeds, the nodulation and growth plants, the interrelationship of the components of seed yield per plant, the nitrogen content in leaves and the number and weight of nodules per plant under the influence of the various treatments derived from the factorial combination consisting of the presence or absence of application of fungicides, EnVigorTM cell protector polymer, inoculation with Bradyrhizobium japonicum, and four periods of application of these treatments before sowing. Soybean seeds from cultivar TMG 131 RR were treated with the Derosal Plus® fungicide (carbendazim + thiram), EnVigorTM cell protector polymer, RizoPlus peat inoculants, and stored at environmental conditions in paper bags for a period of zero, one, two and three weeks before sowing. To evaluate the number of colony-forming units, a completely randomized experimental design with three replications and 16 treatments in a 2x2x4 factorial (fungicide x polymer x periods in anticipation of the application of products to sowing) was used. For the evaluation of other traits, the experimental design was randomized blocks with four replications and 32 treatments in a factorial 2x2x2x4 (fungicide x polymer x inoculation x periods). After seed treatment, colony-forming units (CFU) per gram of inoculant on seeds and the seed physiological quality by the germination test (first and final counting), accelerated aging test, emergence and emergence speed rate of seedlings in the sand bed were evaluated. In a greenhouse two plants were raised in a two-liter vessel each containing soil. At the R3 stage, the number and dry matter weight of nodules per plant, dry matter weight per nodule, nitrogen rate in the leaves, aerial part and root system dry matter weight were evaluated; at the R8 stage, number of pods per plant, number of seeds per pod, weight of hundred seeds and seed weight per plant were evaluated. The data were submitted to the analysis of variance, path analysis and the effects were tested at α=0.05. It was concluded that there was improvement in germination and emergence of seedlings with the application of any product, either alone or combined. The use of polymer, with and without fungicide, increased the average number of colony-forming units in all studied period, maintaining the viability of the product until the sowing date. Seeds with fungicide had higher number of colony-forming units and germination than those without treatment; however, with increased anticipation of product application, the improvement in the germination tended to disappear. Seeds inoculated and treated with fungicide was the best treatment on the accelerated aging test. Inoculation decreased the root dry matter, increased nitrogen rate in the leaves and increased productivity. Fungicide application increased the root system dry matter weight, while the application of polymer increased the size of the nodules. The fungicide + inoculation treatment reduced the number and dry matter accumulation of nodules in the zero period. However, in periods of two and three weeks in anticipation of the application of the products of sowing, the best results were observed with inoculation, followed by fungicide + inoculation treatment. The dry matter weight of nodules per plant is a good indicator of the efficiency of nodulation. The inoculation resulted in higher number of pods per plant, which is the component of greatest influence on soybean productivity. Polymer + inoculation treatment, followed by inoculation alone treatment provided a higher dry matter accumulation of nodules when compared with other treatments in period zero. This treatment also provided higher productivity than the control in all periods of anticipation to sowing.