Sementes de soja recobertas com diferentes fontes e dosagens de fósforo

Abstract

The limitations on the availability of phosphorus in the early growing season could result in restrictions on development, a condition in which the plant does not recover afterwards, even though increasing the supply of phosphorus at appropriate levels. This study aimed to determine the effect of different sources and levels of phosphorus on growth and productivity of soybean plants, grown from seeds treated by the coating process. Two experiments were conducted. The first involved two levels of soil fertility: 1) soil fertilized according to recommendations of the survey for the soybean crop and 2) soil with fertilizer three times higher than that recommended by the survey. It was used the following sources of phosphorus in the treatment of seeds: phytin, dicalcium phosphate, natural daoui phosphate, triple superphosphate and monoammonium phosphate, and five doses: 0, 2, 4, 6 and 8g per 100g of seeds from each source. The evaluations were: emergence, leaf area and shoot dry matter at 25 days after emergence. In the second experiment, it was used only one type of soil, with fertilizer as recommended by the research. It was used the following sources of phosphorus in the treatment of seeds: phytin, calcium phosphate, potassium phosphate and sodium phosphate, five doses of each source: 0, 0.9, 1.8, 2.7 and 3.6 g per 100g of seeds. The evaluations were: emergence, leaf area and shoot dry matter at 25 and 50 days after emergence, number of seeds per plant, thousand seed weight and productivity per plant. The statistical design was a randomized block design with three replications. The results allowed to conclude that: 1) phytin and the monocalcium phosphate, increase the productivity of soybean in the 15% level; 2) the coating of soybean seeds with phosphorus from phytin and monocalcium phosphate, promotes increased leaf area and dry weight of soybean plants; 3) the emergence of the soybean plants is adversely affected when using sodium phosphate,Triple superphosphate or monoammonium phosphate in the treatment of seeds.