Relationships between nitrogen utilization and grain technological quality in durum wheat: II. Grain yield and quality

The relationships between grain quality and N utilization in durum wheat (Triticum durum Desf.) have not been very thoroughly investigated. The aim of this study was to evaluate the effects of N fertilizer rate and water regime on grain yield and quality under Mediterranean conditions in relation to N utilization. Four durum wheat cultivars (Appio, Creso, Ofanto, and Simeto) were grown in field trials under two water regimes (irrigated and rainfed) at three N levels (0, 60, and 120 kg ha–1) in southern Italy during two cropping seasons. At harvest, grain yield and its main components, protein and gluten content, gluten index, sodium dodecyl sulfate sedimentation test, rheological indices dough strength alveograph index (W) and tenacity/extensibility ratio (P/L), and grain yellow index were determined. For the rainfed treatment in the first (drier) year, a decrease in grain yield consistent with an increase in protein content, gluten index, and W and P/L indices was observed. With increasing N level, protein content increased in both growing seasons but a significant improvement in technological parameters was observed only in the first year, mainly under rainfed conditions. Among the investigated cultivars, only Simeto always showed both good yield and quality performance. The positive correlation between plant N content at anthesis and protein content indicated a significant contribution of pre-anthesis assimilation. The high correlations found for both N translocation and N harvest index with technological indices suggest that lately remobilized N might increase the protein polymerization degree, with a consequent improvement in grain quality.