ISHS Acta Horticulturae 563: International Conference on Environmental Problems Associated with Nitrogen Fertilisation of Field Grown Vegetable Crops
EFFECT OF EARLY AND LOCALISED NITROGEN FERTILISATION ON GROWTH, YIELD, EARLINESS AND FERTILISER USE EFFICIENCY OF FIELD EGGPLANT |
| Authors: | A. Rosati, V. Magnifico |
| Keywords: | fertigation, urea |
| Abstract:
The effects of short-term deficiency of soil N at transplanting and the effectiveness of early and localised N fertilisation were studied on field eggplant (Solanum melongena L.). Pre-transplanting some of the plantlets (T1) were irrigated with water while the others (T2 and T3) were irrigated twice with a water based solution of urea, providing 0.25 kg N ha-1. In addition some of the plants (T3) receiving the urea solution were then fertigated at transplanting with 23 kg N ha-1 while all other were not. Eight days after transplanting (DAT) all plants were fertigated with 23 kg N ha-1. No other N fertilisation was applied until 30 DAT, after which plants (T1 and T2) were fertigated bi-weekly with N fertiliser until a total of 200 kg N ha-1 had been applied; T3 plants were dropped from this experiment at this time. Net CO2 assimilation rate, measured 8 DAT (pre fertigation), was 9, 24 and 27 µmol m-2 s-1 respectively for the non-fertilised (T1), fertilised before transplanting (T2), and fertilised both before and at transplanting (T3) treatments. Plant dry weights and leaf area were measured and N uptake assessed at transplanting and at 8, 16 and 29 DAT. At eight DAT, non-fertilised plants were half the weight and had a third the leaf area of the plants fertilised both before and at transplanting. Plants fertilised only before transplanting had values of about 80% of those of plants fertilised both before and at transplanting. Although all plants were equally fertigated at 8 DAT with 23 kg N ha-1, the differences in dry weight and leaf area between treatments remained nearly constant at 16 and 29 DAT, and the initial delay in plant development was never recovered. This delay resulted in reduced yield and a later harvest. Crop N uptake was very low during the first 29 days reaching 14.5 kg N ha-1 in the most fertilised treatment. The importance of early and localised N fertilisation is discussed. | |
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