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

Abstract 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 (δ13C) of n-alkanes in historical winter wheat cultivars. We investigated leaf and grain wax n-alkane concentration (ΣalkLand ΣalkG ) and carbon isotopes (δ13CalkL and δ13CalkG) on C29 as well as bulk leaf and grain carbon isotopes (δ13CbulkL and δ13CbulkG) to assess if these wax components changed across five wheat cultivars released from the 1950s to the early 2010s. Results showed that ΣalkL and grain yield increased, while δ13CalkL and δ13CbulkL decreased across the historical wheat cultivars. We found a significant correlation between ΣalkL and shoot biomass at the early growth stage, and a strong correlation between ΣalkL at the grain-filling stage and grain yield. Grain measures, including ΣalkG, δ13CalkG, and δ13CbulkG did not correlate with crop production. Although δ13CalkL 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 ΣalkL has been indirectly selected in breeding efforts to improve crop production in winter wheat, suggesting that greater leaf waxiness confers advantages for crop growth.