GROWTH AND NITROGEN UPTAKE OF TWO BROCCOLI CULTIVARS
Dry weight (DW) accumulation and partitioning, and N uptake and allocation for two broccoli cultivars (Parthenon and Montecarlo) grown in a Mediterranean environment, were studied. Transplanting was done on 25 September 2008 (3.5 plants/m2) and harvesting on 29 January 2009. Plants were fertilized with 130 kg ha-1 of N. Starting from 21 days after transplanting up to commercial maturity of corymbs, eight destructive samplings were performed. At each sampling, fresh and dry weight of leaves, stems and corymbs were recorded. Kjeldahl-N concentration was also determined on dried aerial parts of the plant. Nitrogen uptake data for each cultivar were used for modeling the decrease in N concentration in the aboveground plant DW as affected by plant DW increase, by using the exponential curve: %N=aDW-b. In Montercarlo maximum aerial DW accumulation occurred 15 days before the harvest (5.3 t ha-1), while in Parthenon DW continuously increased up to the end of the growing cycle (5.0 t ha-1). The maximum corymb DW accumulation was reached earlier in Montecarlo that in Parthenon. Montecarlo compared with Parthenon showed higher stem DW and an earlier leaf senescence. No difference was observed in the harvest index (0.26) and in the corymbs fresh yield. Partial factor productivity index indicates that 85.7 kg of fresh product was obtained for each kilogram of N fertilizer. Nitrogen dilution curve fitted for Montecarlo had a and b parameters slightly higher compared with Parthenon curve. Total N uptake was higher in Montecarlo than in Parthenon, while corymb N uptake was 74 and 71 kg ha-1, respectively. Total plant nitrogen use efficiency (NUEtotal), showed by the total aerial DW accumulation per unit of up-taken N (NUEtotal), was similar for both cultivars, whereas Parthenon exhibited higher nitrogen efficiency in head production per unit of up-taken N (NUEyield) than Montecarlo.
Conversa, G., Bonasia, A. and Elia, A. (2013). GROWTH AND NITROGEN UPTAKE OF TWO BROCCOLI CULTIVARS. Acta Hortic. 1005, 633-640
Brassica oleracea, dry weight, partitioning, dilution curve, yield, NUE, PFP