Nitrogen level effect on yield and quality of fertigated processing tomato in southern italy

Summary

This field trial in southern Italy examined the optimal nitrogen fertilisation strategy for processing tomato under fertigation conditions across four N rates (0–300 kg·ha⁻¹). The results show a non-linear response: whilst dry matter and fruit yield increased with N up to 200 kg·ha⁻¹, the highest N rate (300 kg·ha⁻¹) resulted in the greatest dry matter accumulation but reduced nitrogen use efficiency and a declining trend in fresh matter and marketable fruit yield, suggesting over-fertilisation reduces farm productivity and nutrient efficiency.

Regional applicability

Although conducted in southern Italy, the findings on optimal N rates for processing tomato are transferable to United Kingdom protected horticulture and outdoor cropping systems, particularly regarding principles of nitrogen use efficiency and fertigation management. UK farmers and agronomists may adapt the 100–200 kg·ha⁻¹ range as a starting point for their own soil and climate conditions, though UK growing seasons and water availability differ from Mediterranean conditions and would require local calibration.

Key measures

Fresh and dry weight of leaves, stems, and fruits; number of fruits; leaf area; total N content in plant organs (early and late fruit setting, ripening); total and marketable fruit yield; crop N uptake (kg·ha⁻¹); nitrogen use efficiency for total aboveground dry mass (NUE-pt) and fruit dry mass (NUE-ft)

Outcomes reported

The study evaluated the effects of four nitrogen levels (0, 100, 200, 300 kg·ha⁻¹) applied via fertigation on growth, nitrogen uptake, nitrogen use efficiency (NUE), and yield of processing tomato. Measurements included dry and fresh matter accumulation in plant organs, fruit number and yield, crop nitrogen uptake, and nitrogen use efficiency metrics.

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