Effect of Thidiazuron Concentration and Application Period on ‘Royal Gala’ Apple Fruiting and Production

Abstract

-'Gala' apple trees have low fruit set in restrictive pollination situations, being an obstacle to the achievement of high production rates in orchards in southern Brazil, which can be minimized by the use of growth regulators. The aim of this study was to evaluate the effect of thidiazuron concentrations in 'Royal Gala' apple fruiting and production, grown in mild winter conditions. The experiment was conducted during the 2011/2012, 2012/2013 and 2013/2014 crop years in Fraiburgo, SC, on 'Royal Gala' apple trees in Marubakaido rootstock M9 with filter. In all evaluation cycles, the experimental design was a randomized block with factorial arrangement (6x2) with six TDZ concentrations and two application forms, with six replicates, and the experimental unit consisting of one plant. The TDZ concentrations of each treatment were applied split into two seasons. The first application was performed on pink bud stage (E2) and the second application was in full bloom stage (F2). The variables evaluated were: fruit set (%), return bloom (%), number and weight of fruits per plant, mean fruit weight (g) and average number of seeds per fruit. Data were submitted to analysis of variance, in which for significant variables by the F test, analysis of contrast and polynomial regression were performed in order to evaluate the response of variables with increasing TDZ concentration. TDZ is effective even at low concentrations, increasing the production and fruit set of 'Gala' apples in the climatic conditions of southern Brazil.

Effects of Thidiazuron and Pollinator visits on Fruit Set and Quality of 'Maxigala' Apple Trees

“…The use of TDZ without pollinator visits resulted in absence of seeds (Table 3). Fagundes et al (2017) found a small number of seeds in fruits produced with the use of TDZ, with 3.8 to 4.1 for the control and 2.3 to 2.4 for TDZ applications.…”

“…The treatment with only TDZ application resulted in significantly lower fruit weight than those with floral visitors in the 2017/2018 growing season (Table 4). The lower fruit weight found in the treatment with only TDZ application may be connected to the higher number of set fruits, which can lead to increased competition for photoassimilates (Fagundes et al, 2017).…”

The multipotent thidiazuron: A mechanistic overview of its roles in callogenesis and other plant cultures in vitro

“…26 It is also used in plant in vitro cultures to improve yields per plant. For example, Fagundes et al 27 obtained a higher yield of fruits per plant and effective fruit mass by the use of TDZ. Its morpho-regulatory potential has led to its application in plant tissue culture for morphogenic system development.…”

“…It is also used in plant in vitro cultures to improve yields per plant. For example, Fagundes et al 27 . obtained a higher yield of fruits per plant and effective fruit mass by the use of TDZ.…”

Increasing on Fruit Set and Yield of ‘Monalisa’ and ‘Maxi Gala’ Apple Trees Using Plant Growth Regulators

“…The quality of flower buds and the environmental conditions before, during and after flowering are also extremely important factors. Fruit set can be severely impaired by insufficient chilling during the winter, resulting in the asynchrony of the flowering period between cultivars [1], by rains and frosts during the flowering period. Consequently, the grower needs to explore all the possibilities that can contribute to a good fruit set, especially in years of adverse pollination conditions or with low flowering intensity [2].…”