EFFECTS OF NITROGEN ON ACCUMULATION AND PARTITIONING OF DRY-MATTER AND NITROGEN OF VEGETABLES .2. LEEK

Information about the nitrogen demand and response of leek (Allium por rum L.) is scarce, but relevant for optimisation of nitrogen fertilisa tion strategies. The purpose of the current study was to analyse the d ynamics of accumulation of dry matter and nitrogen in leek. Therefore four experiments were carried out with different amounts and different dates of application of nitrogen. Observations included frequent meas urements of dry matter and nitrogen accumulation of leaf blades, leaf sheaths and, if present, scape. Both the amount of nitrogen applied an d the time of application affected the total accumulation of dry matte r and nitrogen in the plant. The relative partitioning rates of dry ma tter increase to the shaft were affected in such a way that the final harvest indices for dry matter (which ranged from 0.32-0.53) were sign ificantly lower at higher amounts of nitrogen applied. The final harve st indices for nitrogen ranged from 0.21-0.35 and were not significant ly affected by amount or timing of fertiliser applications. The total nitrogen concentrations of leaf blades and leaf sheaths decreased with increasing leaf age. Average nitrate nitrogen concentrations over all plant parts were always below 0.4%.