Stable quality traits of soft winter wheat under nonlimiting nitrogen conditions

Abstract

Bread wheat (Triticum aestivum L.) quality is determined by genotype and environment. The aim of this work was to find gluten proteins related to wheat quality independent of crop environment and under nonlimiting N conditions for wheat yield. Field experiments assessing the effect of N rate in soft winter wheat quality parameters were performed in three locations in Navarra (in northern Spain) during 5 yr with a randomized complete block design and four replications. The minimum N rate that produced maximum grain yield (N(op)) was determined for each year. Grain samples from N treatments equal to or above N(op) were milled. Gliadins and glutenins were extracted from white flour. They were separated into alpha plus beta-, gamma-, omega-gliadins, high molecular weight glutenin subunits (HMW-GS), and low molecular weight glutenin subunits (LMW-GS) and they were quantified by reverse phase high performance liquid chromatography (RP-HPLC). Although an increase in N fertilizer rate led to increases in gliadin and glutenin contents as well as dough strength and extensibility, environmental variability differentially affected the synthesis or polymerization of each gliadin and glutenin type. In terms of protein fractions, both HMW-GS and LMW-GS were determined to be the protein fractions best correlated to dough strength (R(2) = 0.78) whereas gamma-gliadins were the best correlated to dough extensibility (R(2) = 0.72) independent of N nutrition, environmental conditions, and water availability.