Optimizing Agronomic Management on a Cultivar Basis: A Case Study with Canadian Prairie Spring Wheat.

The yield gap in wheat is estimated to range between 10-60%. Narrowing the yield gap may be achieved by optimizing GxExM interactions. Small plot research trials were conducted to determine the yield and agronomic response of two Canadian Prairie Spring wheat cultivars, AC Foremost and AAC Penhold, to standard or advanced agronomic management. Both standard and advanced treatments received recommended fertility and seed treatment. In addition, advanced agronomic management received in-crop foliar applications of: 34 kg N/ha as Urea Ammonium Nitrate (UAN) + Agrotain N stabilizer at Growth Stage (GS) 29; Chlormequat chloride PGR at GS30-31; and two fungicides (pyraclostrobin + metconazole at GS39 and prothioconazole + tebuconazole at GS55). Thirteen site years of data demonstrate how these two cultivars require different agronomic management to maximize yield. AAC Penhold showed a 0.37 t ha^-1 yield response to advanced management, but that yield response occurred at only five of the 13 site years. In contrast, AC Foremost had a much larger (0.95 t ha^-1) yield response to advanced management which occurred at 10 of the 13 site years. The yield response of AAC Penhold was more typical at site years with greater than 260 mm of growing season precipitation; however, AC Foremost typically responded in both dry and wet site years, even where growing season precipitation was as little as 116 mm. Additional studies on AC Foremost found that greater than 88% of the yield response was attributed to yield protection due to the fungicide application. Findings from this and associated studies suggest that the genetic disease resistance of AAC Penhold is superior to that of AAC Foremost and therefore different fungicide management strategies must be employed for different cultivars. If producers adapt their agronomic management to match a cultivar’s genetic potential, crop inputs could be used more efficiently while narrowing the yield gap.