Reducing Nitrogen Rate and Increasing Plant Density Accomplished High Yields with Satisfied Grain Quality of Soft Wheat via Modifying the Free Amino Acid Supply and Storage Protein Gene Expression

Abstract

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–1 with 50% top-dressed N and 360 × 104 plants 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.

Chain Terminators and Glutathione Weaken Wheat Dough under Excess Nitrogen Input

“…In agreement with these reports, we observed increased GPC and wet gluten content, a higher Gli/Glu ratio, and a negative correlation between DST and the Gli/Glu ratio in response to higher N rates. Here, a large discrepancy was found between our result and those of Yang et al and Zheng et al, who found that the protein quality index increased as the N application rate increased from 0 kg to an optimum rate under different experiment conditions. In our experiment, the DST and R max decreased when the N rate increased from 100 to 200 kg ha –1 .…”

“…We studied GY5766, which is a bread wheat cultivar, whereas Yang et al . and Zheng et al studied soft wheat cultivars. Additionally, the content of available N in the soil before sowing was much higher in our study (on an average 126.0 mg kg –1 ) than that (on an average 76.4 mg kg –1 ) in the study of Zheng et al…”

Effects of Different Fertilizer Treatments, Environment and Varieties on the Yield-, Grain-, Flour-, and Dough-Related Traits and Cookie Quality of Weak-Gluten Wheat

“…Inconsistent conclusions have been made in different studies of fertilization (especially N fertilizer) for weak-gluten wheat [ 13 , 14 , 15 ]. Under 150 Kg N ha −1 with 50% top-dressed N and 360 × 10 4 plantsha −1 , the grain yield loss of soft wheat can be compensated, while PC can be decreased (Zheng et al 2022) [ 7 ]. The result of the fertilization mode might be attributed to the downregulation of high-molecular-weight genes and low-molecular-weight genes in mature grains [ 7 ].…”

“…The production of Chinese cookies from weak-gluten wheat has been predicted to dramatically increase from 1.05 million tons in 2004 to 14.4 million tons in 2024. Nevertheless, no more than 1.0% of the total weak-gluten wheat grain production can meet the requirement of cookie making for quality [ 6 , 7 ]. PC and WGC of flour are major parameters to evaluate the quality of wheat for special use.…”

“…Therefore, it is important to balance the grain PC and grain yield in weak-gluten wheat through some special cultivation measures. A decrease in nitrogen (N) application can significantly decrease both grain PC and grain yield; however, to some extent, the loss of grain yield can be compensated by increasing the top-dressed N ratio and plant density [ 7 ]. A previous study has revealed that increasing plant density, which is accompanied by an increase in effective ears, can improve the yield and dry matter accumulation while decreasing the grain PC of the soft wheat population [ 16 ].…”