Agroscope, Institute for Plant Production Sciences IPS, Switzerland

Influence of splitting the application of nitrogenous fertilisers on the baking quality of wheat

Certain types of bread products require a high protein content and well-defined rheological qualities. Although Swiss wheat varieties have a high protein content, said content fluctuates a great deal, and in some years is too low for breadmaking. From 2011 to 2013, a study was carried out on four varieties of wheat and seven nitrogen fertiliser application methods. The aim was on the one hand to analyse the influence of the nitrogen fertiliser (dose and splitting of application) on protein levels, and on the other to examine the relationship between the protein levels of the varieties and their rheological and baking qualities. The splitting of nitrogenous fertiliser applications into three rather than two doses not only significantly increases wet gluten content, but also substantially improves qualitative properties. A 20-40-80 kg N/ha split with a final dose when the flag-leaf appears is ideal for increasing wet gluten content without affecting either rheological quality or yield. This split can be recommended when cultivating ‘Top’ class varieties. The results also show that an increase in protein content does not necessarily improve gluten quality, since several parameters stagnate or decrease when nitrogen fertilisation is intensified. This observation can be explained by the stagnation in the proportion of glutenins, as well as by a decrease in gliadins in favour of albumins and globulins. No matter what nitrogenous fertilisation method is used, the variety ‘Runal’ always achieves the best protein levels. Despite its lower protein content, the variety ‘CH Claro’ obtains equivalent results to Runal in the rheological and baking tests.

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