&lt;b&gt;Dormancy of 'Imperial Gala' apple and 'Hosui' pear tree buds in a region of low chill occurrence

Ruy Inácio Neiva De Carvalho,Flávio Zanette,Gabriely Pinto Pereira,Luiz Antonio Biasi,José Carlos Rendoke,Jean Magnus Santos

doi:10.4025/actasciagron.v36i4.17966

<b>Dormancy of 'Imperial Gala' apple and 'Hosui' pear tree buds in a region of low chill occurrence

Ruy Inácio Neiva De Carvalho, Flávio Zanette + Show 4 more

Open Access

https://doi.org/10.4025/actasciagron.v36i4.17966

Copy DOI

Abstract

The objective of this work was to evaluate the dormancy dynamic of Imperial Gala apple tree buds and Hosui pear tree buds in a region of low chill occurrence. Experiments were conducted between April and August in 2007 and 2008. Branches were collected every two weeks from an orchard at Porto Amazonas (Parana State, Brazil). On the last sampling day, an additional set of branches was collected and refrigerated between 4°C and 7°C for 1,440 hours. Dormancy was evaluated using a biological test of single node cuttings isolated in growth chambers (GC) at 25°C with 16 hours of light exposure. The number of chill hours (CH) and chill units (CU) for the region were recorded. The two species were evaluated in separate experiments. We used 11 completely randomized treatments with four replicas for each species. The peak of endodormancy for the Imperial Gala apple tree buds occurred in early June 2007 and from middle June to early July in 2008. The endodormancy of the Hosui pear tree buds oscillated between April and August in 2007 and peaked between June and early July in 2008.

Highlights

Bud dormancy has been studied in several fruit tree species from temperate climates to understand its start, maintenance and end, in special the pome fruits, with apple trees (CARVALHO et al, 2006), pear trees (CARVALHO et al, 2012; MARAFON et al, 2011b) and quince trees (BETTIOL NETO et al, 2011)
To evaluate the natural occurrence of chill, the number of hours of chill (≤ 7.2°C) and the chill units were measured according to the North Carolina model (SHALTOUT; UNRATH, 1983) and the modified North Carolina model using the software Hora FrioTM, developed by Epagri, Brazil, and climate data provided by Instituto Tecnológico Simepar
The chill recorded in the region was insufficient for both of the studied cultivars

Summary

Introduction

Bud dormancy has been studied in several fruit tree species from temperate climates to understand its start, maintenance and end, in special the pome fruits, with apple trees (CARVALHO et al, 2006), pear trees (CARVALHO et al, 2012; MARAFON et al, 2011b) and quince trees (BETTIOL NETO et al, 2011). Hosui pear is one of the most cultivated in Brazil and has shown an increase in planting area (FAORO; ORTH, 2010). It has been shown that bud growth, or rather lack of growth, is a response to a combination of environmental factors (ecodormancy), the influence of other plant organs (paradormancy), or biochemical and physiological events that occur inside the bud (endodormancy) (LANG et al, 1987). Endodormancy is the most important phase of fruit production, but the processes related to its start, maintenance and end remain poorly understood. The expansion of apple and pear tree orchards in regions with warmer winters has made the artificial ending of dormancy an essential

Objectives

Methods

Results