Yield data from the Uniform Southern Soft Red Winter Wheat Nursery emphasize importance of selection location and environment for cultivar development

Authors: BOYLES, RICHARD - Clemson University; Marshall, David; Bockelman, Harold

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2019
Publication Date: 8/15/2019
Citation: Boyles, R., Marshall, D.S., Bockelman, H.E. 2019. Yield data from the Uniform Southern Soft Red Winter Wheat Nursery emphasize importance of selection location and environment for cultivar development. Crop Science. 59(5):1887–1898.

Interpretive Summary: Genetic gain in grain yield in wheat is needed to meet worldwide food requirements. Over the past 20 years in the Uniform Southern Soft Red Winter Wheat Nursery, The average genetic gain has been 1.7% per year.

Technical Abstract: Yield and agronomic data from a regional soft red winter wheat nursery — consisting of 604 advanced breeding lines (ABLs) and 36 testing locations over a 21 yr period — were evaluated to understand recent genetic gains in wheat and determine the impact of selection location and environment on cultivar performance and adaptation. Relative mean yield improvement of ABLs with respect to historical cultivar AGS 2000 was 106 kg ha-1 yr-1 (1.58 bu ac-1 yr-1), equating to an annual genetic gain of 1.6%. Yield gains for wheat during this timespan were attributed to an increase in both yield potential and stability across environments. However, a strong tradeoff (r=-0.36, p-value<2.2e-16) was observed between yield potential and stability. Additionally, distance between selection and evaluation environments was significantly correlated with yield, with yield decreasing as distance between locations increased. Advanced breeding lines had a +221, +126, and -29.6 kg ha-1 yr-1 (+3.29, +1.88, and -0.44 bu ac-1) yield difference over the location mean when the selection location was within, adjacent, and nonadjacent to the trial location zone, respectively. Advanced breeding lines in general performed poorly in production environments west of their selection site. Based on data analyzed, elevation and latitude are significant geographic parameters to consider when determining optimal selection location for production environment. Meanwhile, change in growing degree days between selection and evaluation location had a stronger influence on yield than did precipitation. Findings demonstrate the importance and benefits of breeder collaborations and multi-environment testing on crop improvement, which will be needed to maximize yield gains in the twenty-first century.