Effect of 6-BA+GA((4+7)) and nitrogen fertigation on feathering of 'Golden Reinders' apple nine-month-old nursery trees

Abstract

The apple (Malus x domestica Borkh.) cultivar 'Golden Reinders' was used to study the effects of mixture of 6-BA and GA((4+7)) (Promalin) and nitrogen fertigation to improve branching of nine-month-old nursery trees grafted on 'M9' rootstock. Promalin was applied three times in June in weekly intervals, in concentrations of 0, 500, 1000, 1500 and 2000 mg L-1 to the upper third of trees. Nitrogen (N) was injected weekly at total amount of 50, 100, 150 and 200 kg ha(-1) for season. Obtained results indicated that nursery trees without Promalin treatment were characterized by significantly lower trunk than with Promalin treatments. Application of N through the system in increasing rates significantly contributed to higher values of trunk diameter. Tree leaders were significantly longer in Promalin treatments only when amounts of applied N were above 100 kg ha(-1). However, N influence on height of nursery trees was not confirmed if they were not subjected to Promalin treatment. Total number of feathers and the number of feathers >30 cm were simultaneously increasing with the increase of Promalin rates. The same trend was observed with applying higher amounts of N. Significant interaction effect between Promalin and N confirmed in this study indicates that Promalin treatment has no effect on number of lateral branches without N application. Increasing of Promalin concentrations above 1500 mg L-1 had no significant influence on the number of lateral branches and number of feathers >30 cm, regardless of N amounts.