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

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.

Towards an ideotype for food-fuel dual-purpose wheat in Argentina with focus on biogas production

“…We studied 36 genotypes with contrasting GY that included old and modern cultivars bearing germplasm of 3 different origins (CIMMYT, Criollo and French). In agreement with previous reports, we found high variability in all agronomic traits (GY, SY, HI, and ∆LS) [ 35 , 38 , 50 , 51 ]. When all genotypes were regarded together, we found a positive correlation between GY and SY, in agreement with other authors [ 52 ], which suggests that it is possible to increase SY without compromising GY, a central issue for developing DP cultivars [ 14 ].…”

“…When all genotypes were regarded together, we found a positive correlation between GY and SY, in agreement with other authors [ 52 ], which suggests that it is possible to increase SY without compromising GY, a central issue for developing DP cultivars [ 14 ]. However, despite this positive correlation, high variability of SY can still be found in groups of similar GY (Table 1 , [ 35 ]). These discrepancies regarding SY and GY correlation point out the importance of gaining knowledge on biomass production and allocation in wheat plants [ 38 ].…”

“…However, less attention has been paid to factors affecting wheat straw [ 52 ]. With the development of 2G-biofuel production, efforts on increasing the yield and quality of straw to maximize the overall value of wheat crop are expected to increase [ 35 , 68 ]. An analysis run on GY and HI from many trials in the United States allowed to detect differences in SY among wheat classes [ 33 ] and, here, we report genotype effects on both SY and composition, in agreement with previous reports [ 35 , 38 , 69 ].…”

“…To successfully manage wheat straw as a commodity and to help position it in the biofuel industry, it is crucial to understand the correlations between biomass, GY, and SY [ 33 ], since selecting cultivars with higher SY and without negative effects on GY may constitute a mean to increase the overall straw resource. Even though SY is known to be influenced by several environmental and management factors, including cultivar selection, it is rarely reported in the literature [ 14 , 33 – 35 ]. One of the most frequently used approaches to assess SY is based on empirical models that infer SY from GY statistics [ 36 ].…”

Biofuel production from straw hydrolysates: current achievements and perspectives

“…If biofuel production is profitable, energy crops might be produced instead of food plants (Glithero et al 2015 ; Shortall 2013 ; Sims et al 2010 ). In contrast, cereal straw may represent an ideal resource for biofuel production, as it is a co-product of food production, and thus, its production does not compete with food generation (Townsend et al 2017 ) and a high level of grain production did not have any negative effect on the utilisation of the straw as raw materials for biofuel production (Jørgensen et al 2018 ).…”