Dossiers en cours
2008 / 2009
dph participe à la coredem
(Amélioration des plantes et petits paysans : échec de variétés à haut rendement de mil dans une région aride)
09 / 1997
The role of plant breeders consists, to a large extent, in elaborating new improved varieties for farmers to grow. While some of these varieties get rapidly accepted and widely used, others do not find their way into farmers’ fields.
The observation that farmers in the western and most arid part of Rajasthan were not keenly adopting improved cultivars of pearl millet led Eva Weltzien (of the International Crops Research Institute for the Semi-Arid Tropics) and four other scientists to look deeper into the matter (1).
The improved cultivars were found to perform poorly under stressed conditions (erratic weather patters, highland…), which seemed to explain the low response level of farmers. The analysis can not be complete without addressing the issue of perception underlying farmers’ response.
Increased yield - the driving concept behind most plant breeding efforts - is merely understood as the highest possible grain yield by breeders. Yet it would not occur to a Rajasthani farmer to express yield strictly in terms of grain productivity per unit area. The decline in the quality and area of grazing lands is pressuring farmers to grow pearl millet as a dual-purpose crop: it provides grain for their own consumption and stover for their livestock (a major source of income in this region). And the strenous and uncertain climatic conditions make yield stability a key factor for marginal factors. This is why no matter how high its grain yielding potential, if a variety performs poorly in the event of rainfall shortage or low soil fertility, or if it produces straw of a poor quality, it can not be considered a desirable variety.
For the most part, breeders have failed to develop varieties that maintain a minimum yield under poor soil and water conditions. One obvious reason for this shortcoming is the very set-up of conventional plant breeding research. Trials are carried out in experimental stations where even the least favourable conditions fail to approximate the reality of farmers’ land situation in the semi-arid tropics.
The articulation of plant breeding efforts around the release of a single high yielding variety is also in contradition with farmers’ perception of diversity.
In Western Rajasthan, farmers grow a variety of crops (pearl millet, green gram, cluster bean, moth, and several cucurbits) so as to fulfill as many of their own needs as possible. For a crop such as millet, a farmer is likely to use several varieties to sow the several plots she or he is tending. Maintaining a varied seed stock is also crucial. If a farmer aims at harvesting millet plants featuring large panicles as well as high tillering (number of shoots) and small grain size, for instance, he or she will simply maximize diversity within the stock while selecting the seeds. Some women farmers are reported to counter-select plants with a large number of tillers (which increase harvesting time), and to select early maturing stocks to ensure early availability of foodgrain in the next season. These preoccupations vary from one family to another, from one caste to another, from one area to another, and they are, in a sense, at the root of agricultural diversity.
Because breeders at ICRISAT work on a single variety at a time, they are unable to meet a multiplicity of demands. Indeed, large panicle size and low tillage are incompatible for a single millet plant. According to Eva Weltzien, only farmer-controlled systems of breeding and selection offer the possibility of bypassing such constraints inherent to conventional breeding approaches.
Until now, little effort has been made to document and understand the complex culture of seed selection, production and storage.
Yet, the conservation of agricultural diversity is commonly envisioned as the exclusive preservation of the genetic make-up of domesticated and wild species. This narrow definition leaves out the cultural aspects of diversity embodied in the varied and skilled interactions of farmers with their genetic resources.
On-farm conservation is often disregarded because of its perceived inadequacy to ensure the preservation of genetic purity. Yet, genetic variability itself emanates from the fields. It is, after all, through farmers’ interaction with their seed stock and with the environment that biodiversity developed. The much debated concept of in-situ conservation only retains meaning if it is set in this reality.
1. Kelley, T. G. , Parthasarathy R. , Weltzien, E. , Purohit M. L. , 1996, Adoption of improved cultivars of pearl millet in an arid environment : Straw yield and quality considerations in Western Rajasthan, ICRISAT, Patancheru, Andhra Pradesh, India.
Personal study on biodiversity in India. A book is on the point to be published in India. For further information, please contact the author (see address) or Fph.