8 and position of each kernel. “This provided some very fundamental insights into grain development,” notes McElroy. Through the research process, the question of how to determine if plant stress has affected the development of kernels with so much variation in weight and mass of each panicle was investigated. The answer was to look for differences in kernel thickness patterns. By deconstructing the panicle and measuring the kernels, McElroy was able to determine when the plant was stressed. “If it was stressed later in the season, we saw solid top fill and poorly filled kernels at the bottom,” he explains. This information was compared to rainfall data for each test site to confirm the timing of environmental stressors with the kernel fill results. NEXT STEPS This study’s novel approach to determining how oat stressors impact yield will go a long way to help plant breeders develop more effective selection techniques. McElroy’s novel approach to measuring plant stress response by determining kernel size distribution patterns and measuring kernel thickness is part of an ongoing effort to understand the genetic basis of factors affecting oat yield and quality. “The results of this project will provide a more effective tool for plant breeders to select for specific stress tolerances, particularly those stresses that occur during the grain fill period,” says McElroy. “Ultimately, this information will create more stable, higheryielding oat varieties for Ontario growers.” Funding for this research was provided by Grain Farmers of Ontario, Cribit Seeds, and the Crop Development Centre (University of Saskatchewan). l continued from page 6 This research project received funding from Grain Farmers of Ontario. IN-FIELD TRIALS The in-field studies took place in New Liskeard, Ontario and Sainte-Anne-de-la-Pocatière, Quebec in 2019, and in New Liskeard and West Montrose, Ontario in 2020. Two tests of 36 entries (six check varieties and 30 advanced lines) were grown in standard plots, with three replications at each site. Prior to harvest, 20 panicles were removed from each plot for detailed analysis. McElroy explains that measuring grain fill can be challenging because kernel size, even under good growing conditions, vary considerably within a panicle. “There can be a 10-day difference in flowering time from kernels at the top to the bottom of the panicle, and secondary kernels are always about 30 per cent smaller. So, if wellfilled secondary kernels from the lower part of the panicle weigh less than a poorly filled primary from an upper node, how do we determine ‘who did their best and who didn’t’?” he says. That’s why the research required deconstructing individual panicles — more than 150 in total — to record the mass PGR OAT GRAIN FILL. DISTRIBUTION OF KERNEL SIZE CLASSES OF FOUR LINES AT TWO LOCATIONS. LINES WITH A HIGH PROPORTION OF THICK, HEAVY SEEDS (GROUPS 4 AND 5) ARE DESIRABLE. LINES A AND C SHOWED A SIGNIFICANT INCREASE IN LIGHT KERNELS AT WEST MONTROSE LOCATION, COMPARED TO NEW LISKEARD LOCATION, SUGGESTING SUSCEPTIBILITY TO STRESS DURING GRAIN FILL. LINES B AND D SHOWED SOME STRESS EFFECTS AT WEST MONTROSE, BUT WERE GENERALLY MORE STABLE AND HAD THE HIGHEST PROPORTION OF WELL-FILLED KERNELS. IMAGE COURTESY ART MCELROY.
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