Soil-Based Methods to Screen Soybean Plants for Resistance to Iron Deficiency Chlorosis (IDC) and Seedling Vigor on Calcareous Manitoba Soils
Kevin Baron (Solum Valley Biosciences), Craig Riddell (Riddell Seed Co.), Rick Rutherford (Rutherford Farms Ltd.)
The objective of this project is to develop an improved growth chamber or greenhouse method to enable rapid screening of soybean seedlings for resistance to iron deficiency chlorosis (IDC). IDC is a major stress factor impacting the yield potential and profitability of soybean production in the Interlake and Eastman regions of Manitoba.
The development of a soil-based method to screen for iron deficiency chlorosis is the first step for several related projects. For external clients, such as commodity organizations or private seed companies, N49 Genetics (Kevin Baron, Craig Riddell, Rick Rutherford) has the capacity to screen soybean germplasm for IDC twelve (12) months a year and outside of a field nursery scenario, or even in advance of the planting season. This is advantageous if agronomists or growers are hesitant to plant new genetics that have not be adequately screened on some of the more challenging soils in Manitoba.
Obtaining reliable and consistent visual chlorosis scores (VCSs) between field environments and across growing seasons is also known to be problematic, and this is intimately linked with spatial variability in soil parameters (carbonates, salts) and the unpredictable nature of weather events (e.g. rainfall, cold temperature) that contribute to IDC. If conditions during the growing season are not conducive to IDC symptoms appearing, this method could be accessed to supplement information generated from varietal screening conducted on an annual basis in field environments.
For N49 Genetics, this soil-based method provides a means to continually select IDC resistant seedlings from breeding populations. Over the 2021 and 2022 seasons, N49 Genetics will establish specialized temperature-controlled facilities that enable soybean seedlings to continuously be screened under conditions (soils, daylength, temperature) that mimic the early season growing conditions in Manitoba and Saskatchewan. Development of a soil-based assay also enables selection of root-related traits (e.g. N2-fixation, rhizosphere pH, root foraging) that may not be adequately captured in hydroponic systems.
The equipment & techniques developed in this study were adapted from US researchers seeking to replace hydroponic systems with a more rapid, cost-effective and soil-based method of screening soybean germplasm for salt tolerance (Lee et al. 2008). Locally, MPSG-funded research has also contribued to the development of a hydroponic system at AAFC Morden to screening soybean germplasm for IDC (Hou, 2017). During the course of our study, Jay Goos with North Dakota State University also published a technical report detailing a sand:soil culture method of inducing IDC symptoms using the “Cone-tainer™” system (Goos, 2019). Several aspects of the current methodology have drawn up from previously published work.