First attempt to simulate the response of aubergine crops to N supply: a means to optimise N fertilisation
Résumé
Public concern about nitrate pollution of waters from horticultural soils emphasises the need for more efficient ways of using N-fertiliser. This paper examines the effect of N supply on dry matter accumulation and N uptake of aubergine (Solanum melongena L.) crops by combining experimental and modelling work. Plants were grown in Pontecagnano (SA), Italy in a sandy loam soil. N fertiliser (ammonium nitrate) was applied weekly by fertigation, to give a total amount of 50, 200 and 355 kg N ha(-1) in 1997 and 25, 150 and 250 kg N ha(-1) in 1998. Total dry matter and N content of the crop were assessed at two week intervals. N_ABLE, a model developed at Horticulture Research International, UK was used to predict the time course of dry weight and N content of the crop. This model was developed for vegetable crops grown in northern Europe, and has never been used for aubergine, grown under Mediterranean conditions and with fertigation. In the absence of parameter-values specific for aubergine crops, values for cauliflower were used. Experimental results showed that plant dry matter and N uptake increased with increasing N fertilisation on any given date. Total N uptake ranged between 120 for the lowest to 230 kg ha-1 for the highest N fertilisation treatments. Comparison between simulated and observed results showed that the model predicted dry matter accumulation under different N supplies reasonably well. However, the critical-N concentration curve for maximum growth did not match the field data and needs to be parameterised specifically for aubergine crops. Thus, the model appears potentially useful for predicting aubergine crop growth and N uptake in response to N supply, and could be used to optimise N fertilisation of field aubergine crops once appropriate parameterisation has been completed.