SEGREGATION AND GENERAL EVALUATION OF SPUR TYPE OR COMPACT GROWTH HABITS IN APPLES
Three orchards consisting of a total of 28,000 apple seedlings, obtained from crosses made from 1971 to 1980, were evaluated for growth type. Three types were defined: 1) spur characterized by upright and thick growth, short internodes, sparse branching and abundant spurring; 2) compact (non spur) characterized by upright growth, short internodes, frequent branching and less spurring and sometimes more bare wood; 3) columnar characterized by a habit similar to the spur type but with restricted branching and very short internodes with nearly all axillary buds growing into spurs and the tree naturally growing into a sturdy cordon. Approximately 8% of the seedlings were spur type. From the cross of two spur types, 30 to 50% were of this type. From the use of a compact type parent, 20 to 30% of the seedlings were compact. Less than 0.3% of the seedlings were columnar type. When both parents were columnar, 44% of the seedlings were of the type. Factors influencing classification of growth types and possible mode of inheritance are discussed in this paper.
Blazek, J. (1992). SEGREGATION AND GENERAL EVALUATION OF SPUR TYPE OR COMPACT GROWTH HABITS IN APPLES. Acta Hortic. 317, 71-80