The Ohio Corn Performance Test: 1972-2011.

The Ohio Corn Performance Test has been conducted by the Ohio State University Ohio Agricultural Research and Development Center since 1972. The objective of the test is to provide farmers, extension workers, crop consultants, and agribusiness personnel with unbiased agronomic information on hybrids marketed in the state. Testing is currently performed at ten sites in three regions of Ohio (Southwestern/West Central/Central; Northwestern; North Central/ Northeastern). Companies enter a hybrid at all the sites within a testing region. Hybrids are planted either in an early or full season maturity trial based on relative maturity information provided by the companies. In the Southwestern/ West Central/Central region, the relative maturity of hybrid entries in the early maturity trial is usually 110 days or earlier; the relative maturity of hybrid entries in the full season trial is 111 days or later. In the Northwestern and North Central/Northeastern regions, the relative maturity of hybrid entries in the early maturity trial is 108 days or earlier; the relative maturity of hybrid entries in the full season trial is 109 days or later. Hybrids are planted with a commercial type planter adapted for plot planting. Each plot consists of four 0.76 m rows approximately 7.6 m long. Seed companies select a final stand and percent overplant for each hybrid entered. Average test yields have increased nearly 60% since 1972. This dramatic increase in yield can be attributed to improvements in hybrid genetics and changes in cultural practices, especially higher seeding rates.  Average plant populations at harvest have increased from 60,200 plants/ha in 1972 to 89,150 plants/ha in 2011. In recent years, most hybrids entered in the test contained transgenic Bt insect resistance and herbicide tolerance. Non-transgenic hybrids currently account for about 10% of the total entries.