PRODUTIVIDADE, LUMINOSIDADE, COMPOSIÇÃO QUÍMICA E QUALIDADE DA ERVA-MATE

Abstract

The objective of this work was to evaluate the productive behavior of the herb mate cultivated under different luminosity indices caused by different intensities of vegetal cover, as well as to verify the effects of the management method on the chemical and organoleptic characteristics of the commercial product. The work was conducted in an area and yerba mate managed in consortium with a fragment of Mixed Ombrophilous Forest, in the Municipality of Guarapuava, Center-South region of Paraná. Photosynthetically active radiation (PAR) was characterized in all plants of the experimental area, and in the sequence, these were separated into classes, which comprise the treatments, containing five individuals per group, randomly selected, resulting in 20 sample units. To determine the production of commercial biomass, pruning of leaves, branches and fine branches was carried out according to commercial standards. Leaf area determination was performed with ImageJ® Software (Powerful Image Analysis). Determinations of caffeine, nitrogen, phosphorus, potassium, calcium, magnesium and sulfur contents were performed in the foliar tissues, and the samples were collected in pre - flowering culture. In the soil, the determination of the contents of aluminum, phosphorus, potassium, calcium, magnesium and sulfur were carried out, and the samples were collected in the crown projection of the yerba mate plants. The statistical analysis of the results was performed using the confidence interval of the means, with 0.95 of significance. The effects of soil chemical variables, leaf nutrient concentration, leaf area and yield were determined using multivariate statistical techniques using the Principal Component Analysis (PCA) and Pearson's Correlation Matrix. It was verified that the commercial biomass production of yerba mate had a behavior directly proportional to the luminous intensity, with a mean production of 29.74; 28.34; 14.6 and 4.24 kg plant-1, for the light strata 100, 73, 50 and 30%. As for the variable leaf area, the behavior was inversely, increasing with the decrease of the incident luminosity. Caffeine production was influenced by light intensity, presenting the highest values in the most shaded environments, with 3.77 mg.g-1 and 8.85 mg.g-1, for the 100 and 30% luminosity strata, respectively. Foliar potassium, aluminum in the soil, calcium in the soil and sulfur in the soil showed a reduction in their concentrations with increasing light intensity, while the other variables remained unchanged. In the Correlation Analysis, the luminosity presented a high coefficient of correlation with production, caffeine, leaf area, leaf potassium and potassium in the soil. The Principal Component Analysis (PCA) verified the formation of groups between caffeine, leaf area, leaf potassium and potassium in the soil in the light index 30%, while the production grouped together with the substrate with the highest luminous intensity. By the sensorial analysis no statistical differences in the taste, color, aroma, overall acceptance and purchase intensities were found for products from different luminous intensities. The results evidenced that different photosynthetically active luminosity indices (PAR) on the yerba mate plants provided changes in the productive dynamics, altering the amount of commercial biomass, chemical composition and plant morphology, although it did not present effects on the organoleptic characteristics of the product.