Writers supporting the case for compensation of farmers in centres of diversity dispute the inferences drawn above from the figures of Kloppenburg and Kleinman (1987). They argue that the North is especially dependent on access to exotic germplasm. Even if they are located outside centres of diversity, 'poor farmers in developing countries are far less dependent upon exotic germplasm since they are surrounded by much greater variability' (Fowler and Mooney, 1990, p. 199). The North has a higher reservation price for access to germplasm: '[T]he political 'pain threshold' for Australia, Europe, and North America - with their highly uniform plant varieties and mechanized food processing - is much lower than the threshold for Africa, Asia, or Latin America' (Fowler and Mooney, 1990, p. 200).
Certainly the North, with its greater wealth, has a higher capacity to pay, and a lower elasticity of demand for food as a whole. What these facts do or do not imply for any 'pain threshold' is an interesting question. But here the discussion focuses on a narrower issue: How dependent is the North on continued access to exotic germplasm?
The argument for continued dependence of the North in particular rests on a set of premises about the major crops:
• Major crops are held to be dominated by a small number of cultivars at any one time.
• Cultivars are relatively quickly superseded as they fall prey to disease or are supplanted by newly bred cultivars with higher yields.
• Output from the set of these cultivars is more variable than from landraces due to the small numbers of cultivars and the high vulnerability of each to stress, pests and disease.
• The flow of new cultivars depends critically on the introduction of new germplasm into the set of elite lines from which they are bred.
We will consider each of these propositions in turn.
There is no doubt about the high uniformity of cultivars of major crops in the North relative to the centres of diversity. In 1969, the National Research Council (1972) reported that of 13 major crops (maize, soybeans, wheat, cotton, millet, dry beans, snap beans, peanuts, peas, potatoes, rice, sugar beet, sweet potato) the average number of major varieties was about four, and they accounted for an average of 70% of area planted. Though these figures are now out of date, the general continued dominance of a small number of cultivars in the United States is undisputed. In Europe, a narrow set of popular cultivars dominates major crops in many countries (Vellve, 1992, Ch. 2), and there is little doubt that a similar situation exists in Canada and Australia.
A major reason for the typical dominance of a small number of varieties in production is their superior performance, from the farmer's viewpoint, over a relatively wide range of environmental conditions. The spread of 'high-yield varieties' has been a major source of increased cereal production as population has continued to increase, while acreage expansion has ceased to be a major means of increasing food supply.
An observation that a small set of cultivars accounts for a large share of production does not necessarily imply a corresponding reduction in the variety of germplasm used by farmers. Farmers may maintain their old cultivars on part of their land, even as they adopt widely marketed high-performance germplasm (see Chapter 6).
It is true in general that modern high-yield crop cultivars follow a typical cycle of introduction, diffusion and obsolescence (Reid and Miller, 1989). Duvick conducted a survey of major crops that indicated the typical life span of a cultivar was 7-9 years and falling (Duvick, 1984, Tables 7 and 8).
Though informal discussions in the literature often seem to imply greater variability of elite cultivars relative to landraces, empirical support of this proposition is surprising in its scarcity. Given increasing yields, the coefficient of variation (standard deviation divided by mean) is preferable to the variance or raw standard deviation. Change in variability is, of course, extremely difficult to measure in short time series. Singh and Byerlee (1990) show declining variability in wheat between 1951 and 1986, and no effect of high-yield germplasm on variability. Byerlee and Traxler (1995) show that the coefficients of variation of a set of modern wheat varieties released by CIMMYT has decreased as yields have risen. Even if given cultivars are no more variable than landraces, their very concentration could add to aggregate variability. Consistent with this hypothesis, Anderson et al. (1987) and Hazell (1989) do find increased correlations across countries and regions between the 1960s and 1971-1983, but their results may be dominated by the unusual crop failures of the 1970s. Furthermore, in storable crops, improvement in market competition might induce variation in planned production in response to changes in marketwide stocks (Williams and Wright, 1991).
In the aggregate, there appears to be widespread historical dependence on germplasm from centres of diversity. And the discussion above confirms the reliance on successive generations of improved seeds, each of short duration and containing a small set of high-yielding cultivars. Contrary to common assertions, the current system does not seem, relative to available historical evidence, especially subject to disruption from pests, diseases or other causes. But is it beholden to a continued flow of germplasm from centres of diversity?
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