Corn Grain

Corn Grain Hybrid Test in Tennessee 2021

Location Information


Medium-season Hybrids

Full-season Hybrids

Additional Trial Information

Appendix A (available online only)

Virginia Sykes, Assistant Professor, Variety Testing Coordinator and Agroecology Specialist 
Ryan Blair, Extension Area Specialist, Grain Crops & Cotton 
Aleksandra Wilson, Research Associate, Variety Testing and Agroecology 
Francisco Palacios, Research Specialist, Variety Testing and Agroecology 
Brooke Keadle, Graduate Research Assistant, Variety Testing and Agroecology 
Dennis West, Professor, Corn and Wheat Breeding 
David Kincer, Research Associate, Corn and Wheat Breeding 
Angela Thompson McClure, Professor, Corn & Soybean Specialist 


This research was funded by UT Extension, the Tennessee Corn Promotion Board, and participating companies. 

We gratefully acknowledge the assistance of the following individuals in conducting these experiments: 

East Tennessee AgResearch and Education Center (Knoxville, TN) 
Robert Simpson, Center Director 
BJ DeLozier, Farm Manager 
Cody Fust, Research Associate 
Charles Summey, Senior Field Worker 
Nicholas Tissot, Farm Crew Leader 

Highland Rim AgResearch and Education Center (Springfield, TN) 
Robert Ellis, Director 
Brad S. Fisher, Research Associate

AgResearch and Education Center at Milan (Milan, TN) 
Blake Brown, Center Director 
Weston Bracey, Research Associate 
Bryan Garren, Research Associate 
Jason Williams, Research Associate 

West Tennessee AgResearch and Education Center (Jackson, TN) 
Scott Stewart, Center Director 
Randi Dunagan, Research Associate 

Agricenter International (Memphis, TN) 
Bruce Kirksey, Director 

Middle Tennessee AgResearch and Education Center (Spring Hill, TN) 
Kevin Thompson, Director 
Joe David Plunk, Research Associate 

Additionally, we are grateful for the continued support and dedication of the many county extension agents and cooperators who contribute to these results (for a full list of extension agents and cooperators, see table 2). 

Experimental Procedures: 

AgResearch and Education Center Tests: All corn hybrid trials were conducted in each of the physiographic regions of the state. Tests were conducted at the Highland Rim (Springfield), East TN (Knoxville), Milan (Milan) and West TN (Jackson) AgResearch and Education Centers (REC). The early and medium-season tests were also planted at the Agricenter International Research Center (Memphis). Duplicate plantings of the early-, medium- and full-season tests were made at the Milan and Highland Rim REC for performance testing with and without irrigation. 

The corn hybrids were placed in either the early-, medium-, or full-season tests based on the maturity as reported by the company providing the hybrid. The early season test contained hybrids that had maturity <114 days after planting (DAP); the medium season test contained hybrids with maturity of 114-116 DAP; and the full season test contained hybrids with maturities >116 DAP. All corn hybrid trials were planted to uniform populations per acre at each location using a precision seeding planter. Trials were planted with a goal of 36,000 plants per acre for irrigated plots and 34,000 plants per acre for non-irrigated plots, although final populations varied by location (Table 1). Tests were conducted using 30-inch row spacing. The tests were fertilized with approximately 230 lbs N/a. A portion of the nitrogen was applied prior to planting (e.g. 80 lbs/a) and the remainder was applied as a side-dress (e.g. 150 lbs/a). The plot size was two, 30-ft. rows. Plots were replicated three times at each location. An incomplete block design was used at each location in order to reduce the within replication variation. 

County Standard Tests: The County Standard Corn Tests were conducted in 25 counties in Tennessee and one county in Kentucky. The number of counties varied by test. The County Standard Tests were divided into early-, medium-, and full-season glyphosate resistant and Bt stacked trait tests (same DAP criteria as listed above). Each hybrid was evaluated in a large strip-plot at each location, thus each county test was considered as one replication of the test in calculating the overall average yield and in conducting the statistical analysis to determine significant differences. At each location, plots were planted, sprayed, fertilized, and harvested with the equipment used in the cooperating producer’s farming operation. The width and length of strip-plots were different in each county; however, within a location in a county, the strips were trimmed on the ends so that the lengths were the same for each variety, or if the lengths were different then the harvested length was measured for each variety and appropriate harvested area adjustments were made to determine the yield per acre. 

Growing Season: Corn grain official variety trials were planted between mid-April and mid-May at the University of Tennessee AgResearch and Education Center (REC) locations. Early season rains were light and did not affect corn planting throughout most of the state; however, early season freezes may have hindered growth or planting in areas of higher elevation in late April. Statewide corn planting was on par with the five-year average by mid-May, with 86 percent of corn planted in Tennessee. Hot, dry weather in early to mid-August stressed corn development across the state. By mid-August, 79 percent of the crop rated good to excellent. A fair amount of precipitation, due to the remnants of hurricane Ida at the beginning to mid-September, delayed corn harvest across the state. This put corn harvest 18% behind the five-year average, with only 57% of corn grain harvested by the beginning of October. According to the National Agricultural Statistics Service, Tennessee producers planted 1,040,000 acres this year, an increase of 180,000 acres from 2020. Acreage harvested for grain is projected to be 970,000 acres with a total production of 167 million bushels. This is an increase of 11 million bushels compared to 2020. Average yield for Tennessee in 2021 is projected to be 172 bu/a which is 4 bu/a lower than national average. 

Interpretation of Data: 

The tables on the following pages have been prepared with the entries listed in order of yield performance, the highest-yielding entry being listed first. Mean separation was performed using the Fisher’s Protected LSD (Least Significant Difference) test. The mean trait value of any two entries being compared must differ by at least the LSD amount shown to be considered significantly different at the 5% level of probability. Tests with an LSD value of N.S. indicate there were no significant differences in entry performance within that test. To simplify interpretation, Mean Separation Letters have been listed next to traits evaluated across locations. Hybrids that have any letter in common are not significantly different at the 5% level of probability based on the LSD test. Hybrids with performance statistically equivalent to the top performing hybrid will have an “A” included in the list of mean separation letters next to that entry. 

The coefficient of variation (C.V.) values are also shown at the bottom of each table. This value is a measure of the error variability found within each experiment. It is calculated as the ratio of the square root of error variance to the mean yield. For example, a C.V. of 10% indicates that the size of the error variation is about 10% of the size of the test mean. Similarly, a C.V. of 30% indicates that the size of the error variation is nearly one-third as large as the test mean. A goal in conducting each yield test is to keep the C.V. as low as possible, preferably below 20 percent. 


Yield and Agronomic Traits. Seventy-one corn hybrids were evaluated in the 2021 AgResearch and Education Center (REC) tests in Tennessee. There were 27 hybrids in the early- (Tables 4-5), 29 hybrids in the medium- (Tables 8-9), and 15 hybrids in the full-season (Tables 12-13) tests. These hybrids represent 10 different brands (Table 17). The County Standard (CS) tests consisted of an early-season glyphosate resistant and Bt stacked trait test (19 hybrids at 12 locations, Table 6), a medium-season glyphosate resistant and Bt stacked trait test (21 hybrids at 20 locations, Table 10), and a full-season glyphosate resistant and Bt stacked trait test (14 hybrids at 10 locations, Table 14) for a total of 54 hybrids. Common to both the REC and CS tests were 14 early-season, 16 medium-season, and 10 full-season hybrids (Tables 7, 11, 15). Similar to the REC tests, all hybrids in the CS tests were placed in the maturity test for which they fit, regardless of other traits associated with each entry. 

All 71 hybrids evaluated were transgenic, containing genetic modification for a combination of herbicide tolerance (RR, RR2, LL) and insect tolerance (A4, CB, HX1, Q, SS, TRE, VIP 3330, VR, VT2P, VZ, YGCB) (see table 17 for full descriptions of abbreviated traits). The majority of entries had glyphosate herbicide tolerance and VT2P insect tolerance. The breakdown of traits by entry are listed below: 

Herbicide Tolerance Number of Entries Insect Tolerance Number of Entries 
GT, RR, or RR2 58 300GT 
GT, RR, or RR2 and LL 13 D2 
TRE 12 
VT2P 44 

Irrigated vs. Non-irrigated Yields. Duplicate tests were conducted with and without irrigation at Milan and Springfield. At the Springfield location, irrigated tests far out-yielded non-irrigated tests. Irrigated yields exceeded non-irrigated yields by 74, 79, and 90 bu/ac in the Early, Medium, and Full test, respectively. At Milan, yields were more similar between the irrigated and non-irrigated tests with a slight yield advantage in the irrigated tests. Irrigated tests out-yielded non-irrigated tests by 5, 11, and 2 bu/ac in the Early, Medium, and Full test, respectively. 

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