Manipulating Regular Bearing in ‘Golden Delicious’/M9 Apple Trees using GA₄₊₇and Ethephon

Abstract

Control of regular cropping in apple is considered critical for fruit growers to ensure their economical sustainability. Irregular flowering can be mitigated by plant growth regulators thanks to their promotion or inhibition effects. In this study, responses of GA 4+7 and ethephon on alternate bearing in 'Golden Delicious'/M9 were examined. GA 4+7 and ethephon were applied on the same trees during three consecutive years . Flowering, yield, shoot growth, and also some fruit quality parameters were assessed. GA 4+7 appeared to be more effectual to regulate alternate bearing. The alternate bearing index calculated with yield in successive years was high in control (0.91), moderate in ethephon (0.71), and low in GA 4+7 treated trees (0.41). Modified alternate bearing index, based on cluster number, indicated moderate intensity in GA 4+7 (0.53) and high intensity in the others. Although GA 4+7 reduced crop density at about 50%, there was little variation in yield per tree and crop efficiency due to increasing of fruit size. GA 4+7 did not increase shot length after establishment of equilibrium between vegetative and generative growth in 2012. Ethephon slightly reduced vegetative growth and relatively increased fruit size due to the decrease of fruit set.

Induction of Lateral Branching of Sweet Cherry and Plum in Fruit Nursery

“…Higher number of shoots were counted after treatment by preparation containing 6-BAP (Ethe.+Put+6-BAP), which agrees with positive effect of 6-BAP on branching described in several studies (Hrotkó et al, 1999;Magyar and Hrotkó, 2005;Koyuncu and Yildrim, 2008). The longest shoots were measured at trees treated with preparation containing GA4+7 (Ethe.+Putre+GA4+7), which agrees with the results of several authors (Schmidt et al, 2009;Atay and Koyuncu, 2016) where GA4+7 prolonged the length of shoots in different apple varieties by 12-138 %. In this study, the shoot length of the 'Toptaste' variety increased by 70 % and at 'Lipnická' variety by 92.7 % after treatment containing GA4+7 (Ethe.+Pu+GA4+7) compared to control.…”

Understanding mast seeding for conservation and land management

“…Much can be learned about masting from these agricultural systems because they lack the environmental and genetic variability that is present in natural forests [129], and because the genetic basis of fruit and seed production is better known in these crops [131]. At the same time, substantial effort has been made to reduce alternate bearing or masting in these crops through breeding [132], chemical sprays that manipulate flowering [133] and pruning techniques [134].…”

Plant Growth Regulators in Flowering Alternation of the Fuji Suprema Apple Tree

“…Studies aimed at the effect of plant growth regulators in midseason cultivars suggest that the formation of flower buds in cultivars prone to the biennial bearing can be controlled with NAA or Ethephon [9,10]. Another factor that contributes to the alternation are the apple seeds, as it is an important source of gibberellic acid, which can be translocated to the plant and can inhibit the formation of flowers for the next season [11]. The presence or absence of gibberellins influences the flowering of the apple tree, however it is still not well known [7].…”