Late-season N increases improver common and durum wheat quality

The foliar N application at a low rate is a strategy that could be applied by farmers in substitution to the traditional late soil application when there are restrictions on N distribution. The aim of this study was to compare the effect of late-season N fertilization strategies on wheat (Triticum spp.) quality. Field experiments were set up in two different soils, in Northwest Italy. The effect of N fertilization was evaluated in each site on two common (T. aestivum L.) and two durum wheat (T. turgidum L. var. durum Desf.) cultivars. Late-season N was soil-applied (40 kg N ha–1) as ammonium nitrate at heading, or foliar sprayed (5 kg N ha–1) at flowering, and compared with a control without N fertilization after the vegetative growth stage. Nitrogen soil application increased flag leaf greenness (+12%) and grain protein content (GPC) (+15%) for both crops. This fertilization strategy led also to higher test weight (+1.4%), kernel hardness (+14%), dough strength (W) (+42%), and lower tenacity/extensibility ratio P/L (–18%) in the common wheat, and to a lower yellowberry percentage in the durum wheat (–29%). The strategy to apply a foliar N fertilizer at anthesis at a lower rate, although it has a greater cost effectiveness, led to a less effective and stable bread- or pasta-making quality enhancement, with an average increase of GPC and W only in the silt loam soil by 5 and 18%, respectively. This strategy could lead to more successful increase of GPC in soils with a probable lower nitrate leaching during the vegetative stages.