Influence of Planting Date and Seeding Rate on Winter Wheat Grain Yield and Yield Components

Abstract

Winter wheat (Triticum aestivum L.) is commonly seeded over a 60-d period in the Midwest depending on crop rotation options, weather, and other farm operations. This study was conducted to determine whether winter wheat seeding rates should be altered depending on planting date and cultivar. Seeding date and planting rate responses of the cultivars, Merrimac and Cardinal, were evaluated at the University of Wisconsin Arlington Research Station during the 1988 to 1991 growing seasons. Eight planting dates ranged from 24 August to 3 November and seeding rates were 14, 28, 42, and 56 seeds/sq ft. Grain yield and yield components were influenced by all variables and specific interactions. Heads per square feet and kernel weight, two primary yield components, decreased as seeding was delayed after 12 September. Maximum grain yield occurred when planting Cardinal on 3 September using 28 seeds/sq ft. Delaying Cardinal planting to late September required a seeding rate of 42 to 56 seeds/sq ft to maximize yield. When planted in September and early October, Cardinal had higher yields than Merrimac due to heavier kernel weight. Changes in yield components allowed plants to adjust to varying conditions as planting was delayed. As grain yield decreased with a planting delay into October, kernel weight and heads per square feet continued to decrease for both cultivars. When planting was delayed past 3 October in 2 of the 4 yr, Merrimac had greater kernel weight, which translated into higher Merrimac grain yields than Cardinal. Grain yields of wheat planted in late October decreased due to yield component response to environment and to stage of plant development when growth ceased. These results can be used to improve establishment and yield of winter wheat, especially when planting at dates that are not always optimum. Research Question Producers aiming for maximum winter wheat grain yields need to begin with successful establishment of the wheat crop in the fall. Optimum planting date and seeding rate are necessary if one wants to attain high yields. This study compared planting date and seeding rate of two cultivars of varying winterhardiness to determine which combination produced maximum grain yields. Literature Summary Previous planting date research has determined that early seeding allows better stand establishment leading to greater yields. Research in Canada established that once planting date is determined, maximum yield for that date will be attained if yield components are managed by adjusting the seeding rate. Cultivars with different degrees of winterhardiness may influence optimum planting date and seeding rate. No published literature was found that examined the interaction of cultivars with planting date and seeding rate for the soft red winter wheat growing region of the Midwest. Study Description This study was conducted for 4 yr, 1988 to 1991, at Arlington, WI, using wheat management practices to maximize grain yield. Date: Eight planting dates in 10-d increments from late August through early November Cultivars: Merrimac-very winterhardy Cardinal-moderately winterhardy Rates: 14, 28, 42, and 56 weeds sq ft Applied Question Are optimum winter wheat seeding rates influenced by planting date and cultivar? Cardinal produced higher yields than Merrimac at all seeding rates when planted prior to 1 October when averaged over all 4 yr of our study (Fig. 1). While cultivars frequently responded differently to planting dates and seeding rates we did not find significant three-way interactions for grain yield. As planting was delayed into October, Merrimac grain yield decreased less rapidly than Cardinal. Merrimac planted in mid-to-late October also provided more consistent yields than Cardinal. We found maximum grain yields could be obtained by seeding Cardinal at 28 to 56 seeds/sq ft up to the third week in September. Growers could save seed costs, however, by using 28 to 42 seeds/sq ft, since the higher rate offered no advantage with early planting dates. When planting date is delayed past 1 October, yields are consistently higher at seeding rates of 42 to 56 seeds/sq ft for both cultivars; however, growers could reduce their risk of crop failure by switching to a more winterhardy cultivar, such as Merrimac. Profitability of winter wheat in the Midwest was the primary objective of our work. We recommend planting higher yielding, less winterhardy cultivars, using lower seeding rates early in the fall for maximum yields. If planting is delayed into October, we recommend that growers switch to more winterhardy cultivars and increase seeding rates. Figure 1Open in figure viewerPowerPoint Effect of planting date and seeding rate on yield of a. Merrimac and b. Cardinal SRWW, averaged over 4 yr, 1988–1991.