High Throughput Characterization of Wheat Photosynthetic Efficiency, Biomass, and Yield.

Selecting genotypes for low heritability traits such as yield, biomass, and quantitative disease resistance in plant breeding programs, requires large amounts of time, effort and resources. The Wheat Breeding and Genetics program at Michigan State University is testing the potential of a new tool, called PhotosynQ (photosynq.org), to rapidly measure photosynthetic parameters and possibly predict biomass and yield of breeding lines. In the trial, photosynthetic parameters, leaf area index (LAI), disease pressure, and yield were measured in 30 Michigan adapted wheat cultivars. Plants were grown in three replicate plots in a completely randomized alpha lattice block design at two locations: Richville and Mason, MI. At the Richville site, plants were grown under a high management regime that included a fall treatment of 28% N (30 lbs N/acre), a spring treatment of urea (90 lbs N/acre), and two fungicide treatments—Quilt to control early-season fungal disease and Prosaro to control fusarium head blight and other late-season diseases. Quilt was applied at Feekes 8.5-9.0 and Prosaro was applied at anthesis. At the Mason site, one trial was under the high management regime, while a second trial was under low management. The low management only included a single spring treatment of urea (90 lbs N/acre). All plots were treated with Affinity BroadSpec for weed control. Photosynthetic parameters, including photosystem II efficiency and chlorophyll content, were measured at 4 growth stages (at two week intervals) throughout the growing season. On a given day, each plot was measured 4 times by randomly selecting representative flag leaves. LAI, disease pressure, and yield were measured on a per plot basis. Hourly weather data was collected at both locations using local weather stations. Across all locations and cultivars, photosystem II efficiency, chlorophyll content, LAI values and bu/A averaged 0.29, 36.35, 2.13, and 85.2 respectively. The complete data will likely paint a comprehensive picture of wheat photosynthesis over the course of the growing season. We anticipate that plants with higher photosynthetic efficiency and LAI will have higher grain yield.