The objective of this research was to determine under field condition the accumulation and exportation of macronutrients by watermelon plant. The experiment was carried out in the Borborema region, State of São Paulo. The samples were taken at the 15, 30, 45, 60 and 75 days after transplanting (DAT), for dry mass determination and accumulation and exportation of N, P, K, Ca, Mg and S. The dry mass accumulation was slow until 30 DAT, intensifying later with the beginning of the frutification. At the end of the cycle, the average contribution of the vegetative part was of about 31% and of fruits 69%. The accumulation of the nutrients followed the curve of dry mass accumulation. The period of larger demand for the nutrients N, Ca and Mg occured from 45 to 60 DAT and for P, K and S from 60 to 75 DAT. The vegetative part was responsible for 29,6% of the total accumulated and the fruits for 70,4%. The nutrients in decreasing order of accumulation were: K>N>Ca>Mg>P>S. To yield of 40 t ha-1 the exported of nutrients by fruits were: 106.4 kg ha-1 of N, 11.1 kg ha-1 of P, 118.0 kg ha-1 of K, 4.3 kg ha-1 of Ca, 6.8 kg ha-1 of Mg and 6.0 kg ha-1 of S.
Citrullus lanatus (Thunb.); plant nutrition; growth
