A greenhouse experiment was carried out from November 2005 through April 2006, at UNESP, Jaboticabal, SP, Brazil, to study dry mass production and macronutrient distribution and accumulation by Ipomoea nil, an important weed of annual and perennial crops in Brazil. The plants were cultivated in 7 liter pots, with sand substrate daily irrigated with Hoagland & Arnon nutrient solution. The experimental design was completely randomized with four replications. The treatments corresponded to the evaluation times, at 14 day intervals, beginning 21 days after emergence (DAE). In each evaluation, the plants from four pots were analyzed for dry mass accumulation and mineral nutrition. I. nil showed small dry mass and macronutrient accumulations at the beginning of the experimental stage. These accumulations intensified after 77 DAE, reaching the maximum theoretical value at 123, 122, 124, 121, 119, 121 and 125 DAE, for dry mass, N, P, K, Ca, Mg and S, respectively. Leaves and stems were the main organs responsible for dry mass accumulation by I. nil plants. K and N were the macronutrients extracted at higher amount by this species.
weeds; morning-glory; dry mass; macronutrients
