Heterosis?

Jean-Pierre Berlan and Richard C Lewontin, "Operation Terminator"

    In 1907 Hugo de Vries, the most influential biologist of his day who "rediscovered" Mendel's laws (4), was the only one to realise that in an applied science like agricultural genetics, economics took precedence over science: what is profitable affects, or even determines, what is "scientifically true" (5).
     He investigated replacing the technique of improving cereals by isolation, which dated back to the early 19th century and was based on the fact that the plants go on to breed true - and therefore bring no profits to the investor - by the continuous selection method. According to this method, justified by the best science of the time, Darwinism, varieties "deteriorate" in the farmer's field. This method cannot improve the plants, as was demonstrated empirically by Nilsson at the Svalöf Institute in Sweden in 1892 and confirmed by the earliest work inspired by Mendel at the beginning of this century. Thus, even then, a technique that was profitable but incapable of bringing the slightest progress replaced one that was useful to society but generated no profits...
     Ignorant of the history of their own discipline and of the work of de Vries in particular (6), the 20th century's agricultural geneticists repeated the same scenario. At the end of the 1930s they triumphed with "hybrid" maize, which was extravagantly fêted (7). The technique of hybridisation, which has become the model for agronomic research the world over, is now used in around 20 food species and a dozen others are likely to follow. Poultry of every kind and a large number of pigs are also "hybrids". On the strength of a sham theoretical explanation of hybrid vigour, heterosis-superdominance (8), geneticists have tried since the mid-1930s to get the hybrid technique generally accepted following their success with maize in the United States. "Hybrids increase yield", they say. This puts the theory of heterosis in a nutshell: having different genes - "hybridity" - is beneficial per se.
     In reality, what distinguishes this varietal type from all the others is the reduction in yield in the next generation - that is, in plain terms, sterility. As a result, the farmer is obliged to buy his "seed" in every year. But varietal progress can only come from improving populations by selection, the very thing that this quest for hybrids prevents. Apparently unaware of what they are doing, the agricultural geneticists have dialectically overturned reality: they state they are using a biological phenomenon, heterosis, to increase yield, while actually using inbreeding to create sterility.

see also:

Berlan, J. P. and R. Lewontin (1986). "The Political Economy of Hybrid Corn." Monthly Review 38(July-August): 35-47.
Berlan, J.-P. and R. Lewontin (1986). "Breeders' Rights and Patenting Life Forms." Nature 322(28 August): 785-788.

GRAIN, "Hybrid rice in Asia: An unfolding threat" March 2000

Heterosis as a myth

Scientists have yet to explain how heterosis works and some, such as Jean-Pierre Berlan, of the Institut National de la Recherche Agronomique in France, believe that it is actually a myth. Berlan maintains that while rice may demonstrate some hybrid vigor , "The real phenomenon is inbreeding depression." 61 Hybrids appear to produce high yields because they out-yield the parental lines they were crossed from by a significant margin. However, Berlan argues that yields from the parental lines are depressed by the many backcrosses that breeders must make for them to be stable. Thus, hybridisation does not necessarily produce "improved varieties"; it only improves upon the parental lines.

While the scientific theory of heterosis remains unexplained, the economic impact does not. The costs of hybrid rice seeds are very high: up to 15 times higher than seeds from elite inbred varieties. 62 The major problem is that seed yields are very low, making seed production costly. Farmers who buy these expensive seeds season after season face the added burden of low market prices for their harvest. The selling price for hybrid rice is significantly lower than the price of regular rice in both India and China, two countries with the most experience.

Some farmers call hybridisation "the scam of the century." 63 Why? If you compare the trajectory taken by two contrasting crops in a country like France – wheat, which is self-pollinated like rice, and corn, which cross-pollinates and can easily be hybridized – the picture is shocking. Wheat and corn were both grown from local populations until hybrid corn took off 40 years ago. In those 40 years, the public research sector continued to work on improving non-hybrid wheat, while the private sector took control of corn breeding, which became entirely devoted to hybrids. The result for the farmer is clear. Wheat yields between the early 1960s and the late 1990s were multiplied by 2.2 whereas the corn yields barely doubled. At the end of the four decades, wheat seed prices were three times the cost of the grain whereas corn seed prices were 30 times the cost of the grain. For hybrids, then, the yield increase has been lower but the price increase has been spectacular. This is why farmers feel short-changed by hybrization: the science is "not explained and unexplainable" , 64 the yield increases have not matched those of the inbred crops and yet the seed prices have shot through the roof. Research to improve the performance of open-pollinated corn varieties – which the private sector is not interested in, since farmers can save the seed – might have provided much more sustainable options than hybrids. Will the same happen in rice?

61 . Personal communication, 26 January 2000.
62 . S.S. Virmani, "Hybrid Rice", op. cit. , p. 403.
63 . Jacques Laigneau, "La guerre des semences fermières", Coordination Rurale, Auch, décembre 1999.
64 . Ibid.