Effect of crop load on apple tree growth and productivity in the first year of planting

Abstract

High quality one-year-old nursery trees of the apple cultivars 'Golden Reinders', 'Granny Smith' and 'Red Chief', with more than seven lateral shoots, were planted in 2008 bearing fruits the same year. Two levels of crop load (3 and 6 fruits per tree) were applied in cultivars 'Red Chief' and 'Granny Smith', whereas six levels of crop load (3, 6, 9, 12 and 15 fruits per tree) in cultivar 'Golden Reinders'. Control treatment without fruits was also included in all cultivars. Planting distance was 3.2× 0.8 m and the trees were trained like slender spindle. Crop load in cultivar 'Red Chief' did not influence on trunk cross sectional area (TCSA), while a reduction of TCSA was recorded in treatments with 9 or more fruits per tree in cultivar 'Golden Reinders'. Crop load increased also the growth in cultivar 'Granny Smith'. Number of shoots and total shoot length decreased on more fruitful trees of cultivar 'Red Chief' in relation to control treatment. 'Golden Reinders' had both lower number of shoots and total length when 9 or more fruits were left in the trees, while this trend were observed in 'Granny Smith' when only 6 fruits per tree were left. Crop load influenced the yield of cultivars, as trees with 6 fruits produced 4.6 t ha-1 in cultivar 'Red Chief', 4,03 in cultivar 'Golden Reinders' and 4,7 t ha-1 in cultivar 'Granny Smith'. By increasing crop load above 6 fruits per tree, fruit weight decreased in cultivars 'Red Chief' and 'Granny Smith'. Fruit weight of cultivar 'Golden Reinders' was decreased only in trees with 15 fruits. Crop load reduced flower buds the following year in cultivar 'Red Chief'. However, cultivars 'Granny Smith' and 'Golden Reinders' with 3 and 6 fruits per tree formed enough reproductive buds for optimal yield in the second year.