London (24.6.08) – There has recently been extensive discussion, much of it inadvertently (or deliberately) misconceived, about yields from GM crops. CropGen accordingly published the following letter in The Guardian:

The original GM developments were designed primarily to aid farmers to obtain more output from each unit input of labour, machinery and chemicals, or to devote less input for each unit of output (Green agenda poses thorny problems, June 20). Their decision would be influenced by the market: for a production surplus, reducing input costs could be more important than raising yields. Under conditions of shortage, higher yields might be the better choice.

In some cases GM produced immediate yield benefits. A maize or cotton field suffering from insect attack will generate clear yield increases if replaced with insect-resistant GM varieties. Better control of weeds, on the other hand, may give valuable reductions in production costs with only modest yield gains.

Crop varieties are tailored to specific conditions. Genetic modification proceeds through two stages: the sought-after property has first to be transferred successfully into a recipient plant and must then be moved by conventional breeding methods into the many production strains; that takes time and not all environmental and soil conditions are instantly catered for. Farmers anxious to benefit from the new technology sometimes use varieties adapted for other regions, thereby not benefiting from the full potential advantages. That may have happened with cotton in India and elsewhere; the practice tends to be more prevalent in countries which delay the enactment of facilitating legislation.

Plant genetics has developed so rapidly over the past two decades that when the industry recently announced a commitment to double yields of maize, soybeans and cotton by 2030 and to develop crops needing 30% less water, land and energy to grow, they were talking from positions of understanding, experience and reality. It may well be possible to achieve such targets, but they are different from the objectives governing developments hitherto.

Source:

Vivian Moses (24.6.08). Yields are only one aim of GM crops. The Guardian (http://www.guardian.co.uk/environment/2008/jun/24/gmcrops.agriculture)

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