Alverez, E.
The following lines from the Cornell breeding program were selected in 1957 to study the inheritance of fruit firmness.
LINE FIRMNESS INDEX
1957 1958
Soft parents (Averages of 5 fruit) (Averages of 60 fruits)
54-149 108 133
Valiant 120 132
Red Jacket 116 123
Firm parents
56-409-4 159 175
54-527-1 152 150
55-37 156 165
Firmness indexes were determined from readings obtained with the pressure
tester designed by Dr. A. R. Hamson.The soft lines were crossed to the firm ones in the winter of 1957-1958. The resulting F1's were grown in the summer of 1958 and the following firmness indexes (averages of 30 fruits) were recorded from them:
(Figures in brackets correspond to firmness indexes obtained for the breeding
lines in the summer of 1958.)Firm lines 54-527-1 and 55-37, when crossed to soft lines 54-149 and Valiant, produced F1 fruits which were softer than the soft parent; all other F1's produced fruits with a firmness index intermediate between the parental values. This suggests the possibility of more than one genetic system operating in the inheritance of firmness.
In the winter of 1958-1959, all F1's were backcrossed to both parents and about 2700 plants from parental F1, F2 and backcross generations were grown in the field, during the summer of 1959, in a completely randomized design. Firmness indexes were determined for five fruits from each plant with the pressure tester. The data are being analyzed at the present time in an effort to understand the inheritance of fruit firmness in the lines studied.