Avaliação do desenvolvimento de manjericão - Ocimum basilicum L. - em latossolo vermelho contaminado com zinco

Abstract

Contamination of soil by metals may occur through natural or anthropogenic interference. Metals are found naturally due to their presence in the parent rocks, but not readily available for plant consumption. Antropic actions interfere with balance and can make metals available, contaminating the soil. Among the existing metals, there are those classified as micro and macronutrients for plants. Zinc is one of the metals classified as an essential micronutrient for plants but at high concentrations it becomes toxic and can cause damage to plant physiology. The goal of this study was to evaluate the growth and alterations in the visual symptomatology of basil - Ocimum basilicum L. - in soil contaminated with increasing doses of zinc. The experiment was carried out with eight different zinc concentrations (C0 (control), C1 (0.60 g.kg-1), C2 (0.080 g.kg-1), C3 (0.121 g.kg-1), C4 (0.241 g.kg-1), C5 (0.482 g.kg-1), C6 (0.694 g.kg-1) e C7 (1.446 g.kg-1)), in five replicates at each concentration, yielding a total of 40 samples. The study was carried out in greenhouse from August to November 2018, respecting the period of 90 days for the growth of Ocimum basilicum L., under conditions of luminosity and natural temperature. Physical and chemical analyzes of the soil were carried out, where it was possible to classify it as a Red Latosol Distroferric. The maximum adsorption capacity of zinc, C5, was determined by adjusting using the Freundlich's Isotherm. From the maximum capacity, all other concentrations were established considering values above and below it. During the duration of the experiment, biweekly counts of leaf numbers and height measurements were made, as well as observations on visual symptomatology, including the appearance of flowers. After 90 days, the plants were harvested and removed from the containers with metal and the roots were washed and analyzed for visual symptomatology. Statistical analysis ANOVA was performed in order to validate the data found with measurements of leaf and flower heights and counts. No significant differences were found between the treatments. In the first fortnight there was alteration in the leaf tonality in the treatments from the C5, however, during the work presented similar tonalities. Flowers appeared earlier in treatments with higher concentrations of metal, indicating that zinc accelerated the plant development. The roots of treatments C5 to C7 presented reductions of branching, increase in thickness and darkening of the main roots. The height increased uniformly in all treatments. The results indicate that Ocimum basilicum L. is developmentally tolerant in media with zinc contamination.