Abstract

Desmodium incanum DC., popularly known as pega-pega, is a wide spread leguminous plant in fields in the state of Rio Grande do Sul in Southern Brazil and is well accepted by the cattle as forage. However, its forage potential is currently threatened, due to the replacement of natural grasslands by agricultural crop and grazing lands and because of the poor pasture management associated with high stocking rate, making it necessary to search for alternatives for the preservation of this genetic resource. The aim of this study was to test variations in the composition of culture media in order to optimize the development of in vitro plantlets of D. incanum. The study was divided into three stages: the first test, evaluated different compositions of MS medium, varying concentrations of nutrients, especially macronutrients (MS 50%; MS 50% and macronutrients at 25%; MS 100% and macronutrients at 50%; MS 100% and macronutrients 25%); the 2^nd test evaluated different concentrations of MS medium nutrients, especially micronutrients (MS 50%; MS 100% and micronutrient at 50%; MS 50% and micronutrients at 25%); and the 3^rd test, in which varying concentrations of IBA (0, 0.5, 1.0 and 1.5 mgL^-1) were evaluated. In Test 1, the culture media with components diluted to 50% provided better development for D. incanum in relation to the media with 100% of the components, and MS 50% was the best treatment. In Test 2, the MS medium with 25% of micronutrients and 50% of other components provided the best growth. In Test 3, the species D. incanum responded positively to the addition of IBA with an increase in root development.

Key words: In vitro, forage, pampa biome, leguminous plant, mineral nutrition.