PREFACE AND FOREWORD

The papers contained in this volume of Acta Horticulturae report the Proceedings of the First International Symposium on Rootstocks for Deciduous Fruit Tree Species. Keynote speakers and authors of selected contributed oral and poster presentations were given the opportunity to submit a manuscript for publication. These manuscripts were reviewed by the symposium Editors. Only those papers judged suitable for publication following the authors consideration of reviewer suggestions appear in this volume of Acta Horticulturae. The ISHS acknowledges and appreciates the contribution of all editors and reviewers. They have made a significant contribution to improving the quality of this publication.

The ISHS Board of Directors

FOREWORD

This first International Symposium organised by the Rootstocks Working Group of the Fruit Section (now the Pome and Stone fruit section) was held at the Mediterranean Agronomic Institute of Zaragoza (IAMZ), Campus of Aula Dei, Zaragoza, Spain, between the 11th and 14th of June 2002. The Symposium was organised by the Estación Experimental de Aula Dei of Consejo Superior de Investigaciones Científicas (CSIC) together with the International Centre for Advanced Agronomic Mediterranean Studies of Zaragoza (CIHEAM-IAMZ), under the auspices of the International Society for Horticultural Science (ISHS). Support was also provided by the Asociación Interprofesional para el Desarrollo Agrario (AIDA), the Sociedad Española de Ciencias Hortícolas (SECH), the Servicio de Investigación Agroalimentaria de la Diputación General de Aragón and local nurseries, such as Agromillora Catalana S.A.

Previously, the Rootstock Working Group of the Fruit Section has jointly organised Symposia in collaboration with other Working Groups, particularly the Orchard Plantation Systems and Environmental Physiology Working Groups, and this was the first time that the group had organised a Symposium on its own. It proved a huge success, attracting 175 delegates from 30 different countries. Although the Symposium title emphasised fruit species, several interesting and valuable contributions on nut crops were also presented.

The opening ceremony was presided over by the CSIC delegate of Aragón, Dr. Juan Bartolomé. Welcome words of Dr. Bartolomé as well as of the Convener, Dr. M.A. Moreno, referred to the scientific activities and information from CSIC related to rootstock research at the Campus of Aula Dei. The ISHS and SECH were represented and brief addresses given by Dr. Tony Webster, Chairperson of the ISHS Fruit Section, and Dr. Victor Galán, President of the SECH.

Major themes covered by this symposium and reported on in this volume of Acta Horticulturae are: rootstock and interstock mechanisms, compatibility/incompatibility, germplasm resources, breeding and selection objectives and methods, rootstock propagation and tree raising, rootstock and interstock testing and evaluation methods, evaluation for biotic and abiotic stress factors, rootstock and interstock effects on fruit quality and storage, and biotechnology. Almost 50 oral papers were presented, with an additional 105 papers displayed as posters.

The scientific session on rootstock and interstock mechanisms focused on reviewing the previous research and presenting current research aimed at trying to understand how dwarfing and other rootstocks bring about their many beneficial effects on scion growth and cropping. Most research on the dwarfing mechanism now focuses on the possible role of plant hormones, in particular cytokinins, auxins and abscisic acid in the rootstock effects, although effects on scion water relations and the translocation of solutes still receives some attention. Unfortunately, we are still some way off being able to understand how dwarfing rootstocks work.

In a subsequent session the methods of breeding and selection of rootstocks for fruits and nuts was considered, with an emphasis on conventional hybridisation techniques. This session also described the results of these programmes and the production of new stocks for pome and stone fruits, as well as for walnuts and pistachios. Whilst traditional priorities, such as dwarfing remain, there is an increased emphasis on breeding and selection rootstocks which adapt trees to unfavourable environmental conditions. Use of rootstocks for this purpose is likely to expand in the future as the requirement for sustainable and environmentally friendly systems of fruit and nut culture expands. A large number of oral and poster presentations focused on the various methods and results of rootstock and interstock field testing. Trials evaluating new rootstocks for apples, pears, plums, cherries, peaches, apricots, persimmons, as well as for almonds and pistachios were described.

In a session on trials of rootstocks used for alleviating biotic and abiotic stress conditions, the benefits of using rootstocks to overcome pests such as nematodes, diseases such as fireblight, Valsa and Eutypa, and abiotic stress conditions, such as drought, high pH and salinity were discussed. The potential for use of mycorrhizal colonisation of rootstock roots as an aid to alleviation of replant syndrome and to facilitate better tree establishment was also considered.

Sessions on graft incompatibility and biotechnology revealed exciting progress in the use of techniques of molecular biology for rootstock improvement. If the current progress is sustained it is likely that the technique of marker assisted selection (MAS) will play an increasing role in rootstock breeding and should facilitate reductions in the current high costs of rootstock breeding. Genetic engineering of rootstocks is still at an early stage of development, although exciting progress in developing rootstocks with fireblight resistance was described.

One whole day during the symposium was devoted to a technical visit to the Jalón valley where local apple, pear, peach and cherry orchards were visited, as well as the nursery Viveros Mariano Soria S.L. and Cosanse, the principal fruit cooperative of the area.

The participants voted to accept the offer of the USA to hold the 2nd International Symposium on Rootstocks at Geneva, New York State, USA, sometime in 2007. The likely convenor will be Dr. Terence Robinson. Suggestions were made by some participants that consideration be given to embracing some of the non temperate crops into this next rootstock symposium. The long time interval between this Ist and the 2nd Symposium (5 years) was thought to be necessary for two reasons. Firstly, it was thought important not to compete with the 8th Symposium on Orchard and Plantation Systems, to be held in Budapest, Hungary, in 2004, for which the Rootstock Working Group is a joint sponsor and active participant. Secondly, it was thought unhelpful to organise a Symposium in 2006, when the next Horticultural Congress was planned for Seoul in Korea. Now, we present this volume of Acta Horticulturae with the reviewed contributions to the symposium through the efforts of the associated editors.

María Angeles Moreno and Tony Webster, editors