Search

In a 2 yr field experiment, we investigated the combined effects of reduced nitrogen (N) rate and increased plant density on the trade-off between the grain protein content (GPC) and the grain yield (GY) in soft wheat cultivars. Reducing N application significantly decreased both GPC and GY; however, to some extent, increasing the top-dressed N ratio and plant density compensated for the GY loss. Optimizing the combination of these three factors (150 kg N ha–1with 50% top-dressed N and 360 × 104plants ha–1) achieved both the required lower GPC for soft wheat and relatively higher GY compared with the conventional cultivation strategy. In addition, this optimized combination downregulated 11 high-molecular-weight glutenin subunits, 8 low-molecular-weight glutenin subunits, 5 α/β-gliadins, and 2 γ-gliadins in mature grains as identified by data-independent acquisition mass spectrometry. Further analysis indicated that the relatively lower free amino acid content and downregulated expressions of the seed storage protein (SSP) synthesis-related genes in filling grains contributed to the reduction of SSP and GPC. Furthermore, the dilution effect induced by a relatively higher accumulation of starch than proteins also partially explained the reduced GPC. Unlike proteins, grain starch accumulation and content depended more on the soluble sugar availability, rather than on the starch synthesis capacity. These findings provide novel insights on simultaneous improvement in the grain quality and yield of soft wheat through synchronized manipulations of N fertilization and plant density.

Understanding the contribution of protein composition and gluten structure to dough property and biscuit baking is crucial to improve soft wheat (Triticum aestivumL.) grain quality. Thus, the relationships of protein composition, gluten structure, and dough rheological properties with short biscuits quality was investigated using 10 Chinese soft wheat varieties. Content of grain protein, flour protein, gliadin, glutenin, and high and low molecular weight glutenin subunits were significantly positively correlated with hardness of biscuit, but negatively correlated with spread factor and sensory score. Gluten of wheat varieties with lower dough strength and better biscuit quality showed thinner walls of apertures and more regular apertures in its microstructure. The gluten with higher strength had more apertures and antiparallel β‐sheets and fewer α‐helices. Moreover, dough with a higher softening degree was easier to stretch and tended to produce biscuits with larger diameter and crispier taste during baking. In conclusion, main wheat quality characteristics that can be used to select grain samples suitable for making tasty biscuits were recommended as follows: flour protein content, wet gluten content and microstructure, Zeleny sedimentation value, and dough softening degree.