Introduction 

Fall forage production potential is one of the major considerations in deciding which wheat variety to plant. For example, dual-purpose wheat producers may find varietal characteristics, such as grain yield after grazing and disease resistance, to be more important selection criteria than an advantage in early forage production potential. Forage-only producers might place more importance on planting an awn-less wheat variety or one that germinates readily in hot soil conditions. Ultimately, fall forage production is a selection criterion that should be considered. For more information on variety characteristics, refer to OSU fact sheet PSS-2142, Wheat Variety Comparison Chart.

Fall forage production potential is determined by genetics, management and environmental factors. The purpose of this publication is to quantify some of the genetic differences in wheat forage production potential and grazing duration among the most popular varieties grown in Oklahoma. Management factors, such as planting date, seeding rate and soil fertility, are very influential and are sometimes more important than variety selection in determining forage production. Environmental factors, such as rainfall amount and distribution and temperature, also play a big role in dictating how much fall forage is produced. All these factors, along with yield potential after grazing and the individual producer's preferences, will determine which variety is best suited for a particular field.

Site Descriptions and Methods 

The objective of the fall forage variety trials is to give producers an indication of the fall forage production ability of wheat varieties commonly grown throughout the state of Oklahoma. The forage trials were conducted under the umbrella of the Oklahoma State University Small Grains Variety Performance Tests. During the 2022-2023 growing season, the forage trials were conducted at the Chickasha and Stillwater test sites. Additionally, first hollow stem measurements were collected at both sites. Weather data for each location is provided in Figures 1 and 2.

Figure 1. Average daily temperature (line graph) and rainfall (bar chart) from Sept. 1, 2022 to March 31, 2023, at Stillwater. Weather data courtesy Oklahoma Mesonet.

Figure 2. Average daily temperature (line graph) and rainfall (bar chart) from Sept. 1, 2022 to March 31, 2023, at Chickasha. Weather data courtesy Oklahoma Mesonet.

A randomized complete block design with four replications was used at each site. Plots at each location were established in a conventionally tilled seedbed. At planting, 5 gal/acre of 10-34-0 was applied in seed furrow at Stillwater and Chickasha. The seeding rate at both locations was 120 lbs/acre. Forage was measured by hand clipping two, 1-m by 1-row samples approximately ½ inch above the soil surface from the interior rows within each plot. There was only one forage sampling date at each location. All samples were placed in a forced air dryer after collection for approximately seven days and weighed. Fertility, planting date and clipping date information are provided in Table 1.

Table 1. Location, planting, clipping and soil information.

Notes: STP: soil test P index; STK: soil test K index.

 
First hollow stem sampling began in early February at the Stillwater and Chickasha locations. It continued every three to four days on a by-variety basis until all varieties reached first hollow stem. Plant samples were collected for each variety by digging an approximately 8-inch section of row and selecting 10 plants randomly from this sample. The largest tiller on each plant was split lengthwise and the hollow stem below the developing grain head was measured. Varieties were considered to be at first hollow stem when the average measurement of the ten plant samples was 1.5 cm (5/8 inch) or greater. For more information on first hollow stem, refer to OSU fact sheet PSS-2147, First Hollow Stem: A Critical Wheat Growth Stage for Dual-Purpose Producers.

Results 

As indicated in Figures 1 and 2, the 2022-2023 fall forage production season included moderate temperatures and low rainfall, which was responsible for low fall forage production in our fields. The average fall forage production at Stillwater was 366 lbs/acre, and values ranged from 204 to 546 lbs/ acre (Table 2). Average forage production at Chickasha was 379 lbs/acre, and values ranged from 230 to 546 lbs/acre (Table 3).

First hollow stem data are reported in day of year (day) format for the winter wheat varieties in Table 4. To provide a reference, keep in mind that March 1 is day 60. The fall and winter months were characterized by extreme drought with temperatures above normal. Many wheat fields did not receive significant rain until the end of March 2023. Lack of moisture likely resulted in late wheat emergence, slow plant development and delayed onset of first hollow stem for the north central region. It also may have comprised differences among varieties on the onset of first hollow stem. The average winter wheat first hollow stem date at Stillwater was day 69 (March 10). This was 20 days later than 2022 (Feb. 18), six days later than 2021 (March 4), and 4 days later than the 20-year average (March 6). There was a 14-day difference between the earliest and latest varieties at Stillwater compared to a 32-day difference in 2022 and 48-day difference in 2021. The average winter wheat first hollow stem date for the Chickasha location was day 71 (March 12). This was five days later than 2022 (March 7), similar to 2021 (March 13), and six days later than the 20-year average (March 6). There was an 11-day difference between the earliest and latest varieties at this location compared to a 36-day difference in 2022 and 45-day difference in 2021.

Acknowledgments 

The authors want to thank the Oklahoma Wheat Commission and the Oklahoma Wheat Research Foundation for providing partial funding for this research.

Seed Sources and Abbreviations 

• AgriMAXX = AgriMAXX Wheat
• AgriPro = AgriPro|Syngenta Seeds
• AGSECO = AGSECO Inc.
• CROPLAN = CROPLAN by WinField United
• KWA = Kansas Wheat Alliance
• LCS = Limagrain Cereal Seeds
• OGI = Oklahoma Genetics Inc.
• OSU = Oklahoma State University
• PlainsGold = PlainsGold Seeds
• WestBred = WestBred Wheat

Table 2. Fall forage production for the winter wheat varieties at Stillwater during the 2022-2023 production year.

Notes: Bolded values are not statistically different from the highest-yielding variety within a column.

Table 3. Fall forage production for the winter wheat varieties at Chickasha during the 2022-2023 production year.

Notes: Bolded values are not statistically different from the highest-yielding variety within a column.
NS: no statistical differences were detected among varieties within a column.

Table 4. Occurrence of first hollow stem (day of year) for the winter wheat varieties sown in 2022 and measured in 2023 at Stillwater and Chickasha

Notes: Double-dashes "--" indicates data not available.