Improved yield and nutrient efficiency in two globe artichoke genotypes by balancing nitrogen and phosphorus supply

Efficient fertilization is a central topic in sustainable agriculture since fertilization strongly influences both crop performances and environmental impact. In several Mediterranean regions, globe artichoke fertilization is still empirically oriented toward nitrogen overdressing and insufficient phosphorus supply. To date, there is a lack of systematic research on the relationships between nitrogen and phosphorus fertilizations, especially in terms of nutrient efficiency. Here, in a 2-year experiment, we studied the effects of two phosphorus fertilization rates, 50 and 150 kg P2O5 ha−1, and four nitrogen fertilization rates, 0, 150, 300 and 450 kg N ha−1, on earliness, yield characteristics and nutrient efficiency indices of two globe artichoke genotypes: the traditional vegetatively propagated ‘Violetto di Sicilia’ and the modern ‘seed’-propagated ‘Opal F1’. The nutrient efficiency indices included partial factor productivity of nitrogen (PFPN), total factor productivity (TFP) and nitrogen agronomic efficiency (NAE). Results show that the highest phosphorus rate allowed to reduce nitrogen supply from 450 to 300 kg ha−1 without compromising earliness or yield of the crop. The highest phosphorus rate also increased PFPN up to 6.9 kg heads dry weight ha−1 kg−1 and NAE up to 2.5 Δ kg dry weight ha−1 kg−1, thus indicating a better nitrogen utilization of the crop, especially at lower doses. ‘Opal F1’, as compared to ‘Violetto di Sicilia’, showed higher PFPN of 8.1 versus 5.2 kg heads dry weight ha−1 kg−1 and TFP of 4.0 versus 2.4 kg heads dry weight ha−1 kg−1, especially at low nitrogen supplies. We conclude that balancing nitrogen and phosphorus supplies, together with the adoption of globe artichoke genotypes characterized by more efficient utilization of soil mineral nutrients, are effective tools to promote both yield performances and a more sustainable nitrogen fertilization of the crop.