Influência do resíduo da indústria de suco de laranja sobre a qualidade do solo e de mudas de Psidium guajava L.

Abstract

Orange is one of the most commercialized fruits in the world, and have great importance for Brazilian exports, with its main processed products being essential oil and concentrated juice, however, its processing promotes the generation of large amounts of waste consisting of leftover fruit, which are currently used in animal nutrition, however, this residue can be reused as a source of organic matter in the soil. The objective of this work was to evaluate the chemical and microbiological quality of the soil with the incorporation of residue from the orange juice industry, as well as to evaluate the development and tolerance of Psidium guajava in soil contaminated with copper and with different doses of residue. In the first experiment, different concentrations of residue (bagasse) were incorporated into the soil (0% residue + 100% soil (control); 20% residue + 80% soil; 40% residue + 60% soil and 60 % of residue + 40% of soil), with 4 different evaluation periods, at 0, 60, 120 and 180 days after the implementation of the experiment, in which the chemical and microbiological quality of the soil was evaluated. In the second experiment, 3 doses of residue (bagasse) were incorporated into the soil (0, 25 and 50%) and subsequently contaminated with copper at concentrations of 0, 50, 100, 200 and 400 mg Cu.Kg-1 of compost, after stabilization of the metal, Psidium guajava (guava tree) was transplanted and after 100 days the plants and the compost were collected, and the contents were evaluated using tecnic of X-RFS of total copper in the soil and the contents of accumulated copper in the plant, it was also evaluated the development of plants and their tolerance to copper through the dry mass of the organs and the tolerance index. In the first experiment, the orange residue promoted improvements in microbiological and chemical quality, promoting an increase in the levels of macronutrients and zinc, and showed a reduction in the soil copper content, indicating that the organic matter incorporated into the soil in this experiment was able to retain copper. In the second experiment, the addition of copper promoted an increase in the total copper content in the compost, an increase in the accumulated copper content in the roots, aerial part and total and affected the development of guava tree, as well as the addition of orange bagasse. The translocation index decreased with the increase in copper contamination and the bioconcentration and bioaccumulation factors showed low efficiency of guava tree in translocating of metal.