Quebra-pedra (Phyllanthus stipulatus (Raf.) Webster, Euphorbiaceae) is a popular remedy used to reduce uric acid in blood and to facilite the elimination of kidney stones. The research was carried out at the Vegetable Crops Experiment Station of the National Institute for Amazonian Research, in Manaus, Amazonas, Brazil, using seeds of a local wild population. A split-plot design was used, where the main plots were the natural environment and 50% shade, the subplots were constituted by doses of 0,2,4,6, 8 and 10 kg of organic compost (OC)/m2 and contained 20 plants in 1 m2. The following characters of the 6 useful plants per subplot were evaluated: stalk diameter at soil level, plant height, root, stalk, branch and leaf biomass (fresh and dry). No significant differences among environments were found for total plant biomass (63.1 g vs 62.3 g fresh wt, 26.6 g vs 25.6 g dry wt, respectively), but were found for height (70.0 cm in sun light vs 96.2 cm in shade) and, consequendy, for stalk biomass (5.1 and 5.7 g dry wt, respectively). Quebra-pedra responds to organic manure, both in total biomass and in all of its components, with an increment of 43% in total biomass between the minimum and maximum treatment, but the benefit/cost ratio suggests that 4 kg of OC/m2 is the maximum amount that is economically viable in the soil used. Total biomass is composed of 17.2% root, 22.3% stalk, 23.1% branches and 37.4% leaves. Plant growth demands considerable potassium but little phosphorous, magnesium or micronutrients.
Quebra-pedra; Phyllanthus stipulatus; Euphorbiaceae; medicinal plant; alternative agriculture; organic compost