OBSERVATIONS ON THE LENGTH OF THE JUVENILE PERIOD IN APPLE SEEDLINGS
Apple breeding at Ahrensburg was taken up in 1976. Consequently results with own material are limited so far. One of the major drawbacks in breeding is the length of the juvenile period which requires several years of patience before the first flowers and fruits can be seen. Thus a lot of effort is put in shortening the juvenile period by breeders.
The length of the juvenile period is a heritable character, however, with a fairly low heritability, as environmental conditions can modify the period considerably (Zimmerman, 1972, review).
A few observations we made on juvenility will be given here. Our apple breeding material in the field comprises some 7 000 seedlings of different age, half of them are intervarietal or clonal crosses (CV) whereas the other half has mildew or scab resistant species in their ancestry (RES).