Relation of Pear Seedling Size to Length of the Juvenile Period1

Abstract

Abstract The age at which flowering began and the stem diameter at various ages were recorded for more than 9,000 pear seedlings planted in orchards at Beltsville. The juvenile period for individual seedlings varied from 2 to 10 years, with a number of seedlings still not flowering after 8 to 10 years. An overall negative correlation of stem diameter with length of the juvenile period was found. Within planting years, this relation was significant only in certain years; within progenies, the relation was significant less than half the time; within a specific cross repeated in different years, the relation varied considerably from year to year. Stem diameter can be successfully used as a preselection criterion for early flowering (short juvenile period) only when these two characteristics are significantly correlated. Since this condition does not exist in most crosses under the growing conditions at Beltsville, stem diameter is not a valid predictor of early flowering.