Análise fitoquímica e resgate de plantas adultas de erva-mate (Ilex paraguariensis St. Hill.) por estaquia

Abstract

The phytochemical analysis and rescue of selected adult plants of mate (Ilex paraguariensis St. Hill.) constitute a great challenge to enable mass cloning. The objectives of this research were to define a fast and efficient method of ultrasonic extraction of total phenolic compounds and flavonoids and to quantify the antioxidant capacity of Ilex paraguariensis leaves using less aggressive and low cost solvent in Brazil (ethanol) and compare with most used solvents (methanol and acetone) find in the literature, aiming at the large scale use; to quantify the contents of these compounds and of the nutrients of the soil and leaves of plants in production of mate; and rescue adult plants by cuttings. The extractor solvents were distilled water and aqueous solutions of ethanol, acetone and methanol, acidified or not with 1% hydrochloric acid. We evaluated the phenolic compounds and the total flavonoid and antioxidant activity with the methods 2,2-diphenyl-1-picrilhidrazila (DPPH), 2,2'-azino-bis (3-etilbenzotiazolin) 6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP). Leaf and soil samples from 61 preselected plants were collected and analyzed for phytochemical contents, and the macro and micronutrient values of leaves and soil were determined. In the rescue of adult plants, seven other mate plants were submitted to girdling to stimulate the emission of epicormic shoots. Shoots were sectioned in single node cuttings, treated with indolebutyric acid (IBA). The cuttings were evaluated for percentages of survival and rooting at 60 days of cultivation in a humid chamber. The two plants with the greatest potential for rooting of cuttings were used to evaluate the effect of the position of collection of the shoots, treated or not with IBA, in the rooting of the same ones. The ideal extraction conditions for total phenolic compounds, flavonoids and the quantification of the antioxidant capacity were found using the FRAP method with mate samples treated with 70 % acidified hydroethanol solvent, submitted to 15 min. of ultrasound and 30 min. of mechanical agitation. Phenolic compounds and flavonoids have high correlation estimations. These compounds also have a high correlation with antioxidant capacity, especially when determined by the FRAP method. The contents of total phenolics, flavonoids and antioxidant capacity show great variation between mate plants in production, enabling the distribution of the same in five different groups aiming selecting for these characters. These compounds are positively correlated with each other and the pH and the availability of phosphorus and zinc in the soil. It is possible to rescue adult plants of mate by cuttings from adventitious shoots. The AIB promotes an increase in the percentage of rooting, which facilitates the rescue of adult plants of mate. The genetic affects the survival of the cuttings and the competence for rooting, besides changing the effect of position of collection of the shoots.