Wheat as a dual crop for biorefining: Straw quality parameters and their interactions with nitrogen supply in modern elite cultivars

Abstract

Abstract Agricultural residues, such as straw, offer an opportunity to produce biofuels and chemicals in biorefineries without compromising food production. The ideal “dual‐purpose cultivar” would have high yield of grain and straw. In addition, the straw should be easy to process in a biorefinery: It should have good degradability, high concentration of carbohydrates, and low concentration of ash. Nitrogen (N) is an essential nutrient important for plant growth, crop yield and grain quality. However, N production and application comes with a high cost and high environmental footprint. The N application should consequently be based on an economical optimum. Limited knowledge exists on how N application affects the potential of straw for biorefining, for example, straw yield and quality. This study, conducted over three cropping seasons, investigated the effect of N supply on the biorefining potential and included 14 wheat cultivars and one triticale cultivar. The N supply directly affected the yield of straw and grain. In addition, the protein concentration in grain and straw increased, but the composition of the straw with respect to carbohydrates and lignin was largely unaffected by N supply. The only significant change was a lower silicon concentration at increasing N application rate, which could be beneficial for lignin valorization in biorefineries. Likely due to the negligible changes in cell wall composition, the effect of N application rate on straw degradability was not significant. N application should therefore primarily be optimized with respect to grain quality and overall yield of grain and straw. Differences between cultivars were also minor with respect to their performance in a biorefinery process. From a breeding and agronomic perspective, focus should therefore be put on maximizing the biomass output from the field, that is, selecting the cultivar with highest grain and straw yield and optimizing the application of fertilizer to get optimum N use efficiency.

Keywords

• biofuels
• cell wall composition
• fertilizer application
• grain yield
• silicon
• straw degradability