The optimal nitrogen (N) rate for potato crops depends on the production system. The objective of this study was to determine the optimal rate of N for the production of minitubers of the basic seed potato grown hydroponically, and to verify the development of the plant in a hydroponic system using a platform of asbestos tiles. The experiment was conducted in a greenhouse at the Department of Plant Science of the Federal University of Viçosa, using shoots of the Asterix cultivar. The treatments consisted of four levels of N (45, 90, 180 and 270 mg L-1), with 10% of each dose of N being applied as ammonium nitrate (N-NH4+) and the remainder in the form of calcium nitrate and potassium nitrate. The largest number (14.1 tubers per plant) and the maximum weight of tubers (68.4 g per plant) were obtained with 188.9 and 270 mg L-1 N respectively. Therefore, the number and weight of tubers were not optimized by the same rate of N. The critical SPAD index in the fourth leaf varies with the age of the plan,t with 38.4 being the largest value reached at 58 DAT.
Potato; Hydroponic systems; Chlorophyll meter; Plant nutrition of nitrogen
