Bud dormancy evolution in apple genotypes with contrasting chilling requirements

Rafael Anzanello,Flávio Bello Fialho,Henrique Pessoa Dos Santos

doi:10.1590/0100-29452022868

Abstract

Abstract This work evaluates how thermal regimes with constant or oscillating temperatures affect the onset and overcome of endodormancy in apple buds with low (‘Castel Gala’) and high (‘Royal Gala’) chilling requirements. Apple twigs were collected in Papanduva-SC orchards during the autumn/winter of 2010 and 2011, and submitted to constant (3°C) or cycling (3/15°C for 6/18h, 12/12h or 18/6h) temperatures for up to 1466 chilling hours (CH). Periodically, a portion of twigs in each treatment was transferred to 25°C, for budburst evaluation. An environmental stress in 2010 caused premature leaf fall on the field, reduced initial budburst in ‘Royal Gala’ samples and interfered with dormancy onset in both cultivars. Cycling temperature treatments with few CH/day decreased partially this effect, allowing buds to enter a dormancy state more efficiently. No significant stress was observed in the orchard in 2011, when dormancy evolution was similar in all thermal treatments, being induced with 54 and 123 CH and overcome with 363 and 662 CH for ‘Castel Gala’ and ‘Royal Gala’, respectively. Apparently, the manner in which apple bud dormancy is induced affects its depth and consequently the total number of chilling hours required to overcome it, making the onset phase fundamental in dormancy studies.

Highlights

Endodormancy occurs during colder months, when bud development is hindered by biochemical and physiological events in the meristem or nearby regions, triggered by environmental stimuli, such as low temperatures or changes in photoperiod
Dormancy was evaluated in twigs of two apple cultivars with high (‘Royal Gala’) and low (‘Castel Gala’) chilling requirements (DENARDI; SECCON, 2005; PETRI et al, 2021)
The initial physiological condition of buds on each sample date is shown on Figure 1, in which budburst follows an asymmetrical sigmoid function of time, modeled by the Gompertz curve (FIALHO et al, 2020)

Summary

Introduction

Apples and other fruit species may undergo dormancy, a period of temporary suspension of visible growth of plant tissue (HAWERROTH et al, 2010). Bud dormancy may occur in three forms: paradormancy, endodormancy and ecodormancy (LANG et al, 1987). Paradormancy is the inhibition of bud growth by influence of another organ of the plant (e.g. apical dominance). Ecodormancy is caused by a temporary environmental restriction, such as water stress or lack of high temperatures. Endodormancy occurs during colder months, when bud development is hindered by biochemical and physiological events in the meristem or nearby regions, triggered by environmental stimuli, such as low temperatures or changes in photoperiod. The exact biochemical mechanisms controlling endodormancy are still not totally known (LEMPE et al, 2022), chilling requirements vary among species and cultivars (KRETZSCHMAR et al, 2011; ANZANELLO et al, 2014a, LONDO; JOHNSON, 2014; FADÓN et al, 2020)

Methods

Results

Conclusion