Parâmetros fenométricos e qualidade da erva-mate em função do sombreamento, vento e cobertura vegetal do solo

Abstract

The herb mate is a Brazilian tree species from the South and Midwestern of Brazil. The quality of its product is determine by its answers to ecophysiological stress, since it is a climax plant which natural habitat is a microenvironment sheltered by larger arboreal extracts. The use of herb mate leaves and branches as chimarrão and tererê beverages are the best-known and popularized ones in the Southern states of Brazil. Currently, there has been a strong competition from more profitable annual crops expanding, and a growing demand for pharmaceutical and food industries due to its rich composition in phenolic compounds and antioxidants, which concentration depends on the production environment condition, resulting in prices increase of the products obtained and the demand for more favorable environment to high quality. Thus, more appropriate cultivation and handling practices are necessary to different micrometeorological conditions, depending on the region and time of year. The objective of this study was to evaluate the ecophysiological responses of herb mate under different levels of shading, concerning the effect of soil cover by plant residues, and mechanical stress resulting from the increase of wind speed. Two experiments were conduct with the DF /UFSM. In experiment one, conducted with young plants of herb mate, the field, the land cover factor (covered and bared soil) and the percentage factor of plants shading (0, 18, 35 and 50%) were evaluated in a completely randomized design. Each sample consisted of 12 plants of a progeny with four replications. In experiment 2, conducted in field by taking advantage of a side protection structure of an old greenhouse, the shading factors were tested (18 and 35%) and wind speed (natural ( 0), 2, 4 and 6 m s-1), being tht each sample had 12 plants in three repetitions. Ventilation was generated by portable fans of different powers. The results showed that the soil cobetura is beneficial for young plants having an increased height, the number of sprouts and more intense staining green hue. The shading of 35 and 50% had higher gain in dry mass, higher leaf area, more intense green color and increased stomatal opening. As the phytochemical composition the concentration of polyphenols and flavonoids was higher in sombremamentos getting 35% higher antioxidant capacity. The application of forced ventilation reduced the number of shoots and stomatal opening, and the leaves were less intense green color and slightly altering the phytochemical composção of phenolic compounds and flavonoids and antioxidant capacity. Young erveiras have better establishment to higher growth and better development with greater accumulation of phytochemicals compounds covered soils with partial shading of 50% and places with little wind.