Introduction

Fall forage production potential is one of the major considerations in deciding which variety to plant. Dual-purpose wheat producers, for example, 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 awnless wheat variety or one that germinates readily in hot soil conditions. Ultimately though, fall forage production is a selection criterion that should be considered. For more information on variety characteristics, please 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 heavy role in dictating how much fall forage is produced. All of 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 2021-2022 crop year, 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 are provided in Figures 1 and 2.

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 is provided in Table 1.

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 eight-inch section of row and selecting ten plants randomly from this sample. The largest tiller on each plant was split longitudinally, 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.

Figure 1. Average daily temperature (line graph) and rainfall (bar chart) from September 1, 2021 to March 30, 2022, at Stillwater, OK. Weather data courtesy Oklahoma Mesonet.

Figure 2. Average daily temperature (line graph) and rainfall (bar chart) from September 1, 2021 to March 30, 2022, at Chickasha, OK. Weather data courtesy Oklahoma Mesonet.

Results

As indicated in Figures 1 and 2, the 2021-2022 fall forage production season included moderate temperatures and low rainfall that was conducive to moderate fall forage production in our fields. Our results reflect these conditions in the sites evaluated. The average fall forage production at Stillwater was 2,775 lbs/acre, and values ranged from 1,777 to 3,277 lbs/acre (Table 2). Average forage production at Chickasha was 1,762 lbs/acre and values ranged from 1,385 to 2,340 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 winter was warmer than usual, and March of 2022 was characterized by warmer and drier than the average. These conditions likely resulted in plant development and the onset of first hollow stem as expected for our region. The average winter wheat first hollow stem date at Stillwater was day 48 (February 18). This was 13 days earlier than 2021 (March 4), similar to 2020 (February 19), and 2 days earlier than the 20-year average (March 6). There was a 32-day difference between the earliest and latest varieties at Stillwater compared to a 48-day difference in 2021 and 23-day difference in 2020. The average winter wheat first hollow stem date for the Chickasha location was 66 (March 7). This was 7 days earlier than 2021 (March 13), 17 days later than 2020 (February 18), and similar to the 20-year average (March 6). There was a 36-day difference between the earliest and latest varieties at this location, compared to a 45-day difference in 2021 and 28-day difference in 2020.

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 1. Location, planting, clipping and soil information.

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

Table 2. Fall forage production for the winter wheat varieties at Stillwater, OK during the 2021-2022 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, OK during the 2021-2022 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 2021 and measured in 2022 at Stillwater and Chickasha, OK.