Heterosis in Modern Single-Cross Hybrids
(in co-operation with Liz Lee)How great an impact does heterosis have on grain yield? After being repeatedly asked this question and discovering that we did not have any current data, we decided to generate some data of our own. The results below are from a study grown during the summers of 2000 and 2001. Using two commercial hybrids we examined the performance of the double-cross hybrid (cross between the two hybrids), the two hybrids themselves, and both F2s (self of the hybrids). The two hybrids used in this study were chosen using the following criteria. (1) They represented germplasm from two different companies. (2) Based on 1998 and 1999 Ontario Corn Performance trials they had similar grain moistures at harvest, indicating similar maturities. (3) Based on 1998 and 1999 Ontario Corn Performance trials they had comparable grain yields. A total of 33 replications of data across 6 environments were used for the analysis presented below.
| Entry | Grain Yield (bu/ac) | Grain Moisture (%) | Test Weight (lbs/bu) | Broken Stalks (%) |
| Hybrid #1 | 125.2 | 23.2 | 51.5 | 7.1 |
| Hybrid #2 | 111.4 | 27.4 | 48.7 | 4.7 |
| Hybrid #1 x Hybrid #2 | 104.4 | 25.3 | 50.4 | 4.9 |
| F2 of Hybrid #1 | 82.4 | 24.7 | 50.8 | 4.9 |
| F2 of Hybrid #2 | 68.3 | 29.6 | 49.0 | 4.1 |
| LSD (0.05) | 7.9 | 1.6 | 3.2 | not significantly different |
Results
- The single-cross hybrids had significantly higher grain yields than the double-cross hybrid.
- The single-cross hybrids had significantly higher grain yields than their respective F2s.
- Inbreeding depression in the two hybrids examined ranged between 34.2% to 38.7%.
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