5. More oil and protein added to standard inbred lines of corn.
A high content of oil and protein has been added to six widely‑used inbred lines of corn by breeding. These lines were crossed to the Illinois High Oil and to the Illinois High Protein Strains of corn. Then the hybrids were crossed back to both parents. After that the backcrossed progenies were selfed for three years. Selection was carried on for high protein by picking ears bearing hard, flinty kernels, and for high oil by picking ears bearing kernels with large germs. No chemical analyses were made until tests were started to determine combining ability. Then it was found that practically all of the new lines were considerably higher in protein content or oil content than the original standard lines used as parents.
The protein content of these new lines ranged from 11 to 22 per cent compared to a range of 11 to 14 per cent for the original standard lines. Oil content ranged from 4 to 10 per cent compared to a range of 2 to 5 per cent for the original inbreds.
Another point of importance is that backcrosses between the first hybrids and the chemical strains gave new lines with higher oil or protein content than backcrosses between the first hybrids and the standard inbred lines. For example, inbred 187‑2 was changed from 4.3 to 7.1 per cent oil when backcrossed to 187‑2, but from 4.3 to 9.8 when backcrossed to the High Oil Strain. Likewise, inbred L‑317 was changed from 11.9 to 16.9 per cent protein when backcrossed to L‑317, but from 11.9 to 22.8 per cent when backcrossed to the High Protein Strain.
Studies are in progress to determine whether the new lines, although higher in protein or oil than the original lines, will produce as high yielding and otherwise desirable hybrids.
C. M. Woodworth and
R. W. Jugenheimer