Genotype of apple trees affects growth and fruiting responses to shoot bending at various times of year

Growing shoots of two apple [Malus sylvestris CL,),Mill, var. domestica (Borkh,) Mansf,] genotypes differing in shoot architecture, the preselection X.3318 and the cultivar 'Chantecler' were bent on three dates during the summer and one in the winter to evaluate the interactive effects of shoot architecture and bending date on lateral shoot development and growth over 3 years. Bending:X.3318; with a high proportion of vegetative lateral shoots on 1-year-old wood, on different dates did-not change the percentage of lateral budbreak (62% to 65%). However, bending in June ar July increased lateral growth on 1- and 2-year-old wood ina mesotonic position, whereas bending in winter reduced lateral growth and redistributed the shoots more basitonically. Both number and weight of fruits were reduced by bending. In 'Chantecler', which forms many flower buds on 1-year-old wood, bending during flower bud formation (June-July) increased the percentage of lateral budbreak (60% vs. 45% for the control) and the number of flower buds. After 3 years of development, early summer treatments reduced the abortion of laterals as compared to, the control. As a consequence, bending increased the number; as well as the weight of fruit: These results shea that the effects of bending on the development and growth patterns of lateral shoots vary with genotype.