Crop breeding has increased the productivity and leaf wax n-alkane concentration in a series of five winter wheat cultivars developed over the last 60 years.

Plant wax n -alkanes are a major constituent of the leaf and grain surface. In this study, we explored what can be learned from the abundance and carbon isotopic composition (δ 13C) of n -alkanes in historical winter wheat cultivars. We investigated leaf and grain wax n -alkane concentration (Σ alkL and Σ alkG) and carbon isotopes (δ 13C alkL and δ 13C alkG) on C 29 as well as bulk leaf and grain carbon isotopes (δ 13C bulkL and δ 13C bulkG) to assess if these wax components changed across five wheat cultivars released from the 1950s to the early 2010s. Results showed that Σ alkL and grain yield increased, while δ 13C alkL and δ 13C bulkL decreased across the historical wheat cultivars. We found a significant correlation between Σ alkL and shoot biomass at the early growth stage, and a strong correlation between Σ alkL at the grain-filling stage and grain yield. Grain measures, including Σ alkG , δ 13C alkG , and δ 13C bulkG did not correlate with crop production. Although δ 13C alkL and grain yield were not correlated at the flowering stage, they were correlated at the grain-filling stage under dry conditions. Our results indicate that increased Σ alkL has been indirectly selected in breeding efforts to improve crop production in winter wheat, suggesting that greater leaf waxiness confers advantages for crop growth. [ABSTRACT FROM AUTHOR]