Project Leader: Jessica Rutkoski, University of Illinois 

 Purpose: For each day wheat is harvested earlier, double-crop soybeans gain about 0.5 bushels per acre on average. Farmers need access to elite early wheat varieties that yield well and avoid early jointing when freeze events could damage reproductive growth. This research helps farmers choose the right wheat varieties to maximize wheat yields and plant double-crop soybeans earlier. Earlier double-crop soybean planting leads to higher soybean yields, ultimately improving economic returns on wheat and double-crop soybean acres. 

Locations of the wheat variety trials in 2024.

Approach: In 2024, researchers grew and collected yield data on commercial wheat varieties at multiple locations. At two sites, Urbana and St. Peter, they also measured jointing and maturity. Jointing marked the start of reproductive growth, while physiological maturity and 14% moisture indicated harvest maturity date. Full data on commercial varieties was reported in the University of Illinois Official Variety Trial publication, available at vt.cropsci.illinois.edu. This research continues for a second year in 2025. 

 Results: 

•  There was a 9-day range in maturity dates among commercial wheat varieties. Takeaway: Selecting the right wheat variety can help growers plant their double-crop soybeans about one week earlier. 
• In Southern Illinois, early jointing was linked to lower yields. Jointing time accounted for 15% of yield variation among varieties. Takeaway: Early-jointing wheat varieties should generally be avoided in our region. Select early-maturing varieties that do not joint early. 
• Earlier-maturing varieties had slightly higher test weights than later-maturing varieties. Scab resistance had a much larger impact on test weight but was not linked to maturity timing. Takeaway: Earlier-maturing wheat varieties may have a slight test weight advantage, but scab resistance plays a much larger role in determining test-weight.  
• Jointing time is partially controlled by the same genes that determine the duration of winter and day length needed to trigger the onset of the reproductive growth phase. Takeaway: Jointing time is genetically controlled, so varieties that do not joint early in your area should always be expected to follow a similar pattern.