Control of lateral buds on the dormancy evolution of apple apical buds

Abstract

The influence of apical dominance is widely studied in fruit trees, but works that show the opposite effect are little known. The objective was to evaluate the influence of lateral buds (LB) on the apical bud (AB) on apple twigs. Were sampled twigs, 20-25 cm of cv. Castel Gala in May/2010 and June/2011, in Papanduva-SC. The experiment was conducted at Embrapa Uva e Vinho - Bento Gonçalves/RS. The treatments were: i) 2010 - I: intact twig; A: removal alternating of 50% LB along the twig; SI: LB lower removal of twig (50%); SS: LB upper removal of twig (50%); SL: removal all LB of twig and SA: removal AB of twig; ii) 2011 - I: intact twig; SS: LB upper removal of twig (50%); FSLS: intact twig with injury below the LB upper. The twigs were submitted to 3ºC per 168, 336 and 504 chilling hours (CH), in 2010, and 456 CH, in 2011 and later transferred to 25ºC, for budburst evaluation. The experimental design was a randomized block with two replications per treatment and 40 twigs per plot. Budburst data were evaluated through maximum budburst, precocity and uniformity. The increase of HF increased the amount of AB sprouted due to overcome dormancy. The LB were strongly affected by apical dominance, regardless of the cold period. The treatments with LB upper presence provided lower percentage of maximum budburst and lower precocity and uniformity of budburst of AB compared to the other treatments. The AB is influenced by LB, especially those located near the extremity upper of twigs.