Bioatividade de um fertilizante no tratamento de sementes e na produção de mudas

Abstract

Biofertilizers are described in Brazilian legislation as products composed of bioactive molecules derived from algae, amino acids, humic substances or plant extracts. Proof of bioactivity must be carried out through bioassays so that these products are registered as biofertilizers, in this way, the farmer will have access to products with proven action. Therefore, the aim of this work is to evaluate the bioactivity of a product composed of humic substances and Ascophyllum nodosum on seed germination and seedling development. Two types of bioassays were performed to assess bioactivity. In seed treatment, two experiments were carried out sequentially. In the first, watermelon, corn and soybean seeds were treated with doses of Fort Raiz® (0, 2, 4, 6 and 8 mL/Kg of seed) to define the model plant. In the second test, soybean seeds were treated with the same doses of Fort Raiz® and the solution containing the mineral fraction isolated from Fort Raiz®. Both studies were conducted in a completely randomized design in a factorial scheme using 4 replications of 50 seeds. In the foliar application, doses of Fort Raiz® and the solution containing the mineral fraction isolated during the development of seedlings of papaya cv. Alliance. Doses of 0, 1, 2, 4, 6 and 8 mL/L were applied after seedling emergence (7 days after sowing) and repeated weekly, totaling 5 applications. This experiment was also implemented in a randomized block design and in a factorial scheme. For seed treatment, it was possible to verify that the species responded differently to the evaluated doses. The germination of watermelon was not affected by the application of Fort Raiz®, while that of corn had a linear decrease. The germination percentage and vigor of the soybean seeds were induced by the application of Fort Raiz®, with a quadratic effect and the best results achieved at an approximate dose of 5 mL per Kg of seed. It was possible to verify that the inducing effect on soybean germination of Fort Raiz® is not due to the mineral fraction, although with a difference only in the dose of 6 mL per Kg of seed. The development of the seedlings was induced by the application of Fort Raiz® and it was evident that the effect was not due to the isolated mineral fraction. Fort Raiz® provided a linear increase in leaf area and dry mass, robustness index, stem dry mass, shoot and total dry mass. The root length, volume and dry mass were not affected by Fort Raiz®, but there was a linear decrease in the root mass fraction, indicating favored shoot development, which may have been caused by the limitation of the tube. It is concluded that Fort Raiz® provides an inducing effect on the germination of soybean seeds and on the development of papaya seedlings, however, studies are needed to verify the bioactivity in the formation of roots in larger containers.