Modern elite winter wheat cultivars use two physiological pathways to achieve yield stability

Identifying target traits for breeding stable, high-yielding winter wheat cultivars is challenging due to the intricate interplays of genotype, environment and management practices. We hypothesized that yield stability could be achieved through multiple genotypic strategies and that agronomic management stimulating these strategies would enhance stability. To test this, three-years of field experiments were conducted using eight high-yielding elite cultivars and three agronomic practices:1) nitrogen levels (220 or 176 kg N/ha), 2) fertilizer application timing, and 3) two sowing dates. Detailed field phenotyping of 130 agronomic, phenological, chemical and physiological traits, resulted in 40,557 measured or derived trait values. Correlation and multivariate analyses suggested that management practices promoting grain number increased yield stability, while nitrogen level influenced the importance of application time and sowing date. Interestingly, modern elite cultivars exhibit two distinct physiological strategies coupling different source capacity and sink demand strategies to achieve genotypic yield stability: (1) coupling high tiller and grain numbers with longer canopy stay-green and higher carbon reserves and (2) coupling high grain length with low tiller number and greater remobilization of pre-anthesis carbon reserves. The integration of multiple physiological pathways could therefore facilitate the identification of trait combinations for yield stability breeding.