In the eastern Great Plains, winter wheat (Triticum aestivum L.) typically is planted from late September through November. However, grain yield and grain quality often are reduced by variable weather conditions in the spring and foliar disease infections. Field studies were conducted in southeastern Kansas from 1990 through 1995 on a Parsons silt loam soil (fine, mixed, thermic, Mollic Albaqualf) to evaluate effects of planting date, with and without a foliar fungicide (propiconazole: (1-{[2-(2,4-dichloro-phenly)-4-propyl-1,3-dioxolan-2-yl] methyl}-1H-1,2,4-triazole), on grain yield, yield components, and grain quality (test weight and protein) of hard and soft red winter wheats with different maturities and disease resistances. In 2 of 6 yr, grain yields of all cultivars planted in late September were reduced significantly by barley yellow dwarf virus (BYDV) infection. Intermediate planting dates in mid- to late October resulted in the best grain yield and quality in most years. Grain yields and test weights of November-planted wheats were more variable and depended on specific environmental conditions. Grain yield and test weight responses to foliar fungicide depended on severity of specific foliar diseases, cultivar disease resistance, and environmental conditions, but significant yield increase occurred 77% of the time. Planting date had no significant effect on foliar fungicide effectiveness. Foliar fungicide had no effect on grain protein, head density, or kernels per head. Results indicate that a foliar fungicide application could be beneficial in protecting grain yield and test weight potential of both hard and soft winter wheat cultivars when conditions are favorable for foliar disease epidemics in the eastern Great Plains wheat-growing region.

Planting Date and Foliar Fungicide Effects on Yield Components and Grain Traits of Winter Wheat

The Crop Environment Resource Synthesis (CERES) models have been developed and utilized for the last 30 years to simulate crop growth in response to climate, soil, genotypes and management across locations throughout the world. We reviewed 215 papers found in the literature that contained field observed data where the CERES models were tested. Over 30 simulated variables of the CERES models have been tested in 43 different countries under various experimental treatments. Across all testing conditions, the CERES models simulated grain yield with a root mean square error (RMSE) of less than 1400 kg/ha (~10% relative error, RE), 1200 kg/ha (~20% RE) and 800 kg/ha (~10% RE) for maize, wheat, and rice, respectively. Phenological development was simulated with less than 7 days difference from the observations in most studies. The CERES models simulated aboveground biomass, harvest index, evapotranspiration, and soil water reasonably well too. The simulations of grain number (up to 4340 root mean square error, RMSE), grain weight (up to 22% error), intercepted photosynthetically active radiation (IPAR, up to 0.41 MJ/plant), leaf area index (LAI, 31.9% error), soil temperature (over 10°C difference), and nitrogen (N) dynamics (up to 80% error) were less accurate. In fact the average error of CERES model simulations tends to be higher under marginal crop growing conditions such as extreme heat or cold, water and nutrient deficit conditions.

A Comprehensive Review of the CERES-Wheat, -Maize and -Rice Models’ Performances

Addition of triticale (×Triticosecale Wittmack) into more diversified cropping systems could provide valuable economic and environmental benefits to producers in the U.S. Corn and Soybean Belt. To maximize triticale value, research was conducted to identify planting dates that allowed maximum dry matter production and N capture. Winter triticale was planted at 10-d intervals from 15 September to 15 October at three Iowa locations: central, northeast, and southwest for two growing seasons: 2002-2003 and 2003-2004. Aboveground dry matter production, N concentration, and N removal were greater at southwest Iowa than central and northeast Iowa. Dry matter production decreased as planting was delayed from late September to late October. Nitrogen accumulation at any time during the spring and summer was greater for September- than October-planted triticale in 2002-2003. At the end of the 2002-2003 season, mid-September-planted triticale had accumulated 37% more N than mid-October-planted triticale. In 2003-2004, total N capture occurring by early May was less for late-October-planted triticale than the other three planting dates, but there were no differences in N capture among the four planting dates from late May until maturity. Dry matter production was greatest when at least 300 growing degree days (GDDs) (base 4°C) accumulated between planting and 31 December. These results suggest that triticale should be planted in September to maximize spring forage yield and N accumulation although later planting dates would provide a higher quality forage if harvest was not delayed into late spring and summer.

Planting Date Effects on Winter Triticale Dry Matter and Nitrogen Accumulation

No-till planting winter wheat (Triticum aestivum L.) following summer crops requires different crop management than continuous wheat. A 3-yr study was conducted to determine if increased seeding rates and N fertilizer rates were required to maximize wheat grain yields following grain sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merr.]. Wheat seeding rates of 67, 101, 134, and 168 kg ha -1 and N treatments of 0, 45, 90, and 134 kg N ha -1 were applied to areas previously planted to grain sorghum and soybean. Grain yield increased as seeding rate increased in all 3 yr, with yield optimized at seeding rates of ≥134 kg ha -1 regardless of the previous crop. Wheat response to N varied with previous crop, with wheat following grain sorghum requiring 21 kg ha -1 more N to maximize grain yields compared with wheat planted after soybean. These previous-crop effects were attributed to grain sorghum producing higher levels of residue and this residue immobilizing a greater amount of available N than soybean residue. Leaf N content decreased as seeding rates increased and increased as N rates increased. Leaf N content had a similar response to N rates and previous crops as grain yields. Grain N content increased as applied N increased. Results of this study indicate that different seeding and N rates are required to optimize wheat yields when no-till planted after grain sorghum and soybean.

Seeding and Nitrogen Rates Required to Optimize Winter Wheat Yields following Grain Sorghum and Soybean

This research investigates the potential impacts of climate change on winter wheat Triticum aestiuum L. production, looking at changes both in the mean climate and in climate variabil- ity, under conditions of elevated atmospheric CO2 concentrations. The study region is comprised of the 5 states of Indiana, Illinois, Ohio, Michigan, and Wisconsin in the US. This analysis was conducted for the period 2050-59 for 10 representative farm locations in the 5 states for 6 future climate scenarios using the crop growth model CERES-Wheat. Wheat is currently the most widely grown crop in the world, with approximately 250 million ha planted each year. This region, while not a critical area for winter wheat production under current climate, is in a marginal area that could become a more important production region under a warmer climate. As such, the impacts of climate change on wheat growth are of great significance both regionally and globally. With future atmospheric CO2 concentrations of 555 ppmv, wheat yields increased 60 to 100% above current yields across the central and northern areas of the study region when modeled for 2050-59 climate change scenarios. In the southern areas of the study region, small increases (0.1 to 20%) and small decreases (-0.1 to -15%) were found. These decreases in yield were more frequent under climate conditions associated with the more extreme Hadley Center greenhouse gas run (HadCM2-GHG, representing a 1% increase in greenhouse gases per year) and for the doubled climate variability analyses. Across all sites, earlier planting dates (Sep- tember 2 is optimal) performed best; yields decreased as planting was delayed. These results have im- plications for spring-planted crops. CO2 fertilization effects also are found to be significant for wheat, representing an average yield increase greater than 20% under future climate scenarios, with greater benefits occurring under more moderate future climate scenarios. Without the effects of CO2 fertiliza- tion in the model, many of the southern locations had greater decreases in yields. The overall climate change impact across the study area resulted in large increases in yields with only a few locations exhibiting decreases, and those decreases occurring only under the more extreme climate scenarios.

https://www.int-res.com/articles/cr2002/22/c022p073.pdf

Sensitivity of winter wheat yields in the Midwestern United States to future changes in climate, climate variability, and CO2 fertilization

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 planing 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 [...]

B. J. Dahlke

Papers

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