chapter eleven Farmer decision making and genetic diversity

25 Pages·2012·1.59 MB·English

GENES in
the FIELD
Bon-farm Conservation
of Crop Diversity
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GENES in
the FIELD
On-Farm Conservation
of Crop Diversity
Edited by
Stephen B. Brush, Ph.D.
INTERNATIONAL PLANT GENETIC
RESOURCES INSTITUTE
IPGRI ROME, ITALY
IDRC
INTERNATIONAL DEVELOPMENT
RESEARCH CENTRE
Ottawa, Canada
LEWIS PUBLISHERS
Boca Raton London New York Washington, D.C.
Library of Congress Cataloging-in. Publication Data
Genes in the field: on-farm conservation of crop diversity / edited by Stephen B. Brush.
p. cm.
Includes bibliographical references and index.
ISBN 0-88936-884-8 International Development Research Centre
ISBN 1-56670-405-7 Lewis Publishers (alk. paper)
1. Crops — Germ plasm resources. 2. Germplasm resources, Plant. I. Brush, Stephen B. Brush. 1943-
SB123.3.G47 1999 99-044933
631.5'23-dc21 CIP
Canadian Cataloguing in Publication Data
Main entry under title:
Genes in the field: on-farm conservation of crop diversity
Copublished by International Plant Genetic Resources Institute.
Includes bibliographical references and index.
ISBN 0-88936-884-8
1. Crops — Germplasm resources.
2. Crops — Genetic engineering.
3. Germplasm resources, Plant.
4. Plant diversity conservation.
I. Brush, Stephen B., 1943-
II. International Plant Genetic Resources Institute.
III. International Development Research Centre (Canada).
SB123.3G46 1999 631.5'23'3 C99-980391-3
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Library of Congress Card Number 99-044933
Printed in the United States of America 1234567890
Printed on acid-free paper
Contents
Foreword
Cany Fowler, Geoffrey C. Hawtin, and Toby Hodgkin
Section I. Introduction and overview
Chapter 1. The issues of in situ conservation of crop
genetic resources 3
Stephen B. Brush
Section II. Population biology and social science
Chapter 2. The genetic structure of crop landraces and the
challenge to conserve them in situ on farms 29
Anthony H. D. Brown
Section III. Case studies
Chapter 3. Barley landraces from the Fertile Crescent: a lesson for
plant breeders 51
Salvatore Ceccarelli and Stefania Grando
Chapter 4. The barleys of Ethiopia 77
Zemede Asfaw
Chapter 5. Traditional management of seed and genetic diversity:
what is a landrace? 109
Dominique Louette
Chapter 6. Keeping diversity alive: an Ethiopian perspective 143
Melaku Worede, Tesfaye Tesemma, and Regassa Feyissa
Section IV. Policy and institutional issues
Chapter 7. Optimal genetic resource conservation:
in situ and ex situ 165
Timothy Sivanson and Timo Goeschl
Chapter 8. The Cultures of the Seed in the Peruvian Andes 193
Tirso A. Gonzales
Chapter 9. On-farm conservation of crop diversity: policy and
institutional lessons from Zimbabwe 217
Elizabeth Cromwell and Saskia van Oosterhout
Chapter 10. In situ conservation and intellectual property rights 239
Carlos M. Correa
Chapter 11. Farmer decision making and genetic diversity:
linking multidisciplinary research to implementation on-farm 261
Devra Jarvis and Toby Hodgkin
Index 279
chapter eleven
Farmer decision making and
genetic diversity: linking
multidisciplinary research to
implementation on-farm
Devra Jarvis and Toby Hodgkin
Introduction
On-farm conservation has been proposed as a strategy to conserve the pro-
cesses of evolution and adaptation of crops to their environments (Oldfield
and Alcorn 1987; Altieri and Merrick 1987; Brush 1991). The conservation of
specific genes or genotypes is secondary to the continuation of the processes
that allow the material to evolve and change over time, remaining adapted
to local agricultural production conditions. A prerequisite, however, for evo-
lution and adaptation is the existence of genetic variation (Lande and Bar-
rowclough 1990; Hamrick and Godt 1997). If the continued use of local
cultivars by farmers is to form part of a conservation strategy, some knowl-
edge of the amount of this genetic variation is needed to evaluate different
approaches. This knowledge needs to be linked to farmer decision making
and acquired over time (Frankel et al. 1995).
In the process of planting, managing, harvesting, and processing their
crops, farmers make decisions that affect the genetic diversity of the crop
populations. Over time they will modify the genetic structure of a population
by selecting for plants with preferred agro-morphological characteristics.
Farmers will influence the survival of certain genotypes by choosing a par-
ticular farming management practice or by planting a crop population in a site
with a particular micro-environment. Farmers make decisions on the size of
the population of each crop variety to plant each year, the percentage of seed
to save from their own stock, and the percentage to buy or exchange
261
262 Genes in the field: On-farm conservation of crop diversity
from other sources. Each of these decisions, which can affect the genetic
diversity of cultivars, is linked to a complex set of environmental and socio-
economic influences on the farmer.
To date, the majority of on-farm conservation case studies have concen-
trated on linking farmer maintenance of local crop cultivars to
environmental and socioeconomic factors at a particular point in time (Glass
and Thurston 1978; Clawson 1985; Richards 1986; Brush 1991, 1995; Brush et
al. 1992; Bellon 1996; Cromwell and van Oosterhout, this volume). These
studies focus on investigating the factors that have influenced farmers to
maintain or not to maintain local cultivars. In some cases, the genetic
diversity of the locally grown cultivars has also been measured at a given
time using genetic diversity indices of allelic richness or allele evenness
within the population (e.g., Zimmerer and Douches 1991), but the primary
concern of the investigation has usually been to describe the circumstances
in which local cultivars constitute a part of production systems.
For the most part, the link between the effect of farmer management
decisions and amount of genetic variation within the crop population has
not been studied in detail. What is the effect of different farmer selection
strategies on the genetic structure of the local cultivar over a number of
years? What happens to the genetic diversity of local cultivars when farmers
change the area planted? At what point will reduction in the area planted to
a specific local cultivar lead to a significant reduction in the genetic diversity
and limit further change? What is the effect on the genetic diversity of local
cultivars of introducing new material or altering selection strategies through
participatory breeding? These questions are important for understanding
changing patterns of production and for those who advocate the use of local
cultivars as components of sustainable production. They are also important
questions for those who see on-farm maintenance of local cultivars as a
component of a national conservation strategy. Without some understanding
of the effect of farm-based decisions on genetic variation, national programs
will lack the information needed to support, assist, or intervene in on-farm
management of local cultivars where they see this as a part of their own
conservation program. The few studies that have begun to look at the
possibilities of a link between farmer decisions and genetic diversity have
necessarily concentrated on one crop in one geographic area and focus on a
particular point in time (Teshome 1996; Casas and Caballero 1996; Louette,
this volume). For a national program to formulate a comprehensive on-farm
conservation strategy, for each relevant within-country farming system,
answers are needed to the questions: (1) which farmer-based decisions affect
whether the amount of genetic diversity within a crop population decreases,
increases, or remains stable over time and (2) where, when, and how do these
decisions affect the genetic diversity within a crop population?
This chapter explores the issues involved in conserving genetic diversity
through farmer maintenance and use of local cultivars. The concern is to
consider the ways in which national plant genetic resources programs might
address these issues. To illustrate this, we first describe the recently initiated
Chapter eleven: Farmer decision making and genetic diversity 263
program of work coordinated by the International Plant Genetic Resources
Institute (IPGRI) which takes the form of a multidisciplinary global project to
investigate on-farm conservation; to build national capacity and explore
community participation in nine countries. We then discuss some central
genetic questions and explore some of the implications of these for national
programs concerned to maximize the diversity conserved.
Linking institutions, disciplines, and methodologies
In 1995, IPGRI, working through national programs, formulated a global
project in nine countries to strengthen the scientific basis of in situ conser-
vation of agricultural biodiversity. The objectives of the project are to:
support the development of a framework of knowledge on farmer
decision-making processes that influence in situ conservation of agri-
cultural biodiversity
strengthen national institutions for the planning and implementation
of conservation programs for agricultural biodiversity
broaden the use of agricultural biodiversity and the participation in
its conservation by farming communities and other groups
The nine countries involved in the project are Burkina Faso, Ethiopia, Nepal,
Vietnam, Peru, Mexico, Morocco, Turkey, and Hungary. In each country,
strengthening the relations of formal institutions with farmers and local-level
institutions to promote on-farm conservation is a major concern. These part-
ner countries were included because each was within a region of primary
diversity for crop genetic resources with worldwide importance. Each has
traditional farming communities that maintain plant genetic resources. The
countries all have national programs organized to conserve crop resources,
which include ex situ conservation facilities, and all indicate a strong interest
in developing a national capacity to support in situ conservation.
The program was formulated with the idea that in situ conservation
activities should not aim to dissuade farmers from adopting new crop vari-
eties that increase food availability or income, but rather to (1) determine
and understand the situations in which local cultivars are maintained by
farmers; (2) identify the key factors which affect farmer decisions to maintain
local cultivars; (3) understand how farmer decision making affects the
amount of genetic variation within crop populations over time; and (4) find
ways to assist the continued selection of local cultivars or cultivars that
conserve local germplasm. The development of any support program is
expected to vary substantially across and within the different countries. The
project emphasizes, therefore, participatory and learning approaches rather
than the development of a specific model. The concern is to understand what
is happening rather than prescribe abstract solutions.
The program supports research on the biological and social bases of in
situ conservation, including (1) collecting a basic data set that links farmer