@article{Massa_Incrocci_Botrini_Carmassi_Diara_Delli Paoli_Incrocci_Maggini_Pardossi_2018, title={Modelling plant yield and quality response of fresh-market spinach (Spinacia oleracea L.) to mineral nitrogen availability in the root zone}, volume={13}, url={https://www.agronomy.it/agro/article/view/1120}, DOI={10.4081/ija.2018.1120}, abstractNote={<p>Spinach is one of the most important green-leafy vegetables, consumed worldwide, and its intake is beneficial for human beings. In this crop, produce yield and quality are closely related to plant nitrogen (N) nutrition. A precise supply of N is also essential for high environmental and economic sustainability. Main aims of the work were: i) to establish relationships between produce yield or quality and mineral N availability in the root zone; and ii) to define an optimal mineral N level to be maintained in the root zone for spinach. Eight experiments were carried out during a four-year-long period under typical Mediterranean climate conditions. Different amounts of N fertilisers were supplied leading to twenty different levels of mineral N in the root zone. Experimental measurements included climate parameters, plant growth, tissue and soil analyses, produce yield and quality indicators. A segmented linear model significantly represented the relationship between crop yield (1.7 to 21.7 t ha<sup>–1</sup>) and soil mineral N concentration (7.6 to 41.0 mg kg<sup>–1</sup>). Basing on this model, an optimal mineral N threshold was fixed at 23.4 mg kg<sup>–1</sup>. Above this threshold, crop yield did not show any significant variations as well as tissue characteristics and produce quality. Plants grown under suboptimal N levels showed reduction in growth, tissue mineral (nutrients) content, and SPAD index. The proposed models could be implemented in fertilisation protocols for the optimization of N supply and the estimation of spinach growth and yield.</p>}, number={3}, journal={Italian Journal of Agronomy}, author={Massa, Daniele and Incrocci, Luca and Botrini, Luca and Carmassi, Giulia and Diara, Cecilia and Delli Paoli, Pasquale and Incrocci, Giorgio and Maggini, Rita and Pardossi, Alberto}, year={2018}, month={Aug.}, pages={248–259} }