Effect of split applications of urea on protein size distribution, physical dough properties, and baking performance of five experimental bread wheat lines

Abstract

Five experimental bread wheat lines (BWL) were grown at the Yaqui Valley Experimental Station in Sonora, México during two consecutive growing cycles. The effect of five nitrogen fertilization (NF) treatments on protein size distribution (PSD), physical dough properties (PDP), and baking performance of the BWL was evaluated. Polymeric and monomeric proteins were evalu-ated by SE-HPLC. PDP were carried out by the National Mixograph and the TA-XT2 Texture Analyzer. Baking performance was evaluated using the straight dough method. Protein content (PC), main protein fractions (glutenins, gliadins, albumins-globulins), and mixograph development time (MDT) were significantly influenced by NF treatment and BWL but not by their interaction. On the other hand, PDP measured by the Kieffer rig, and baking performance were significantly influenced by the main factors (NF and BWL) and their interaction. The amount and timing of fertilizer applied to the BWL modified the PC, PSD, PDP, and bread loaf volume. PDP exhibited a larger variation in comparison to the PSD of glutenins. The split application of 150 kg of urea/ha (50-50-50) to all BWL showed a better loaf volume response than the same amount of urea applied at sowing (150-0-0). The application of 300 kg of urea/ha to all BWL, either at sowing or at three split applications of 100 kg of urea/ha each, resulted in higher flour unextractable polymeric protein (FUPP). On the other hand, the split application of 100-100-100 kg of urea/ha to three of the BWL represented the higher total unextractable polymeric protein (TUPP). Differences on PC and PSD were reflected on differences on PDP and bread loaf volume observed among the BWL.