The citrus industry is an important economical activity in Brazil. The increase and maintenance of citrus groves require the production of 15-20 million nursery plants yearly. Due to the type of nurseries and horticultural characteristics of rootstocks and scions the development of guidelines for best nutrient management of these plants is requiered. This research evaluated the supply of N and Cu, and the growth and nutritional status of 'Pêra' sweet orange nursery trees grafted on 'Rangpur lime' and 'Sunki' mandarin rootstocks. Two levels of N (120 and 240 mg L-1) and four of Cu ( 0, 5, 10 and 20 mg L-1; Cu-EDTA) were applied via fertigation from seedlings transplantation to finalization of nursery plants. The Rangpur lime demonstrated greater vigour compared to the 'Sunki', based on production of dry mass and plant size. Better plant growth was attained at 240 mg L-1 of N and 5 to 10 mg L-1 of Cu, whereas a negative growth was observed with 20 mg L-1 of Cu, which was associated with Cu concentrations in the leaf tissue of 20 mg kg-1 and root of 50 mg kg-1. This negative effect was minimized with greater N supply. Similarly, bud take was optimum with intermediate Cu supply both rootstocks on both rootstocks. Copper demand of 'Pêra' nursery plants was greater for those on 'Sunki' mandarin rootstock and at 200 mg L-1 of N fertigation. Excess of Cu also reduced Mn uptake by plants. Greater Cu concentration was observed in root tissues from the upper part of nursery bags, compared to the lower part which, was in line with the Cu adsorption in the substrate, as indicated by a maximum concentration of 310 mg kg-1 of Cu.
Citrus; mineral nutrition; fertigation; micronutrients; propagation
