Weed Interference in the Morphophysiological and Nutritional Characteristics of Erva-Mate (<i>Ilex paraguariensis</i>)

Abstract

The erva-mate ( <i> Ilex paraguariensis </i> ) represents an alternative crop for agricultural exploitation in South Brazilian farms with potential to export the harvested product. However, there is scarce information about the interference caused by weeds on this crop. The objective of this work was to evaluate the interference of weed species on the morphophysiological and nutritional characteristics of erva-mate. The experiment was installed in greenhouse at the Federal University of Fronteira Sul (UFFS), <i> Campus </i> Erechim/RS, Brazil, in randomized blocks design, arranged in a 4 × 6 factorial scheme, with four replications. In factor A, weed species ( <i> Urochloa plantaginea </i> —Alexandergrass, <i> Bidens pilosa </i> —Hairy beggarticks, <i> Ipomoea indivisa </i> —Morning glory and <i> Conyza bonariensis </i> —Hairy fleabane) were allocated, and in B the populations of these species competing with the erva-mate (0, 1, 2, 3, 4 and 5 plants per pot) were considered. The variables evaluated in erva-mate were sub-stomatal CO 2 concentration, photosynthetic rate, CO 2 consumed, stomatal conductance, transpiration rate, water use efficiency, height, stem diameter, leaf area and shoot dry mass. Concentrations of nitrogen (N), phosphorus (P), calcium (Ca) and magnesium (Mg) were also evaluated. Overall, all weed species and densities among the tested ones harmed the development of erva - mate plants, which was considered as low competitive with weeds.