Global warming could boost apple harvest

BRITAIN could harvest bumper crops of crunchier apples in one of the more welcome consequences of global warming, according to a scientist studying the effects of climate change on crops.

Dr Chris Atkinson, of Horticultural Research International at East Malling, Kent, believes that warmer springs could accelerate plant growth, leading to crisper apples which last longer in storage. Britain's apple crop is worth about pounds 140m a year.

Furthermore, the apples could be grown on trees which have been genetically engineered for disease resistance. In a separate development, researchers at Cornell University in the United States have discovered how to insert genes into apple trees so that they are resistant to 'fire blight', the world's worst bacterial disease of fruit crops.

According to Dr Atkinson, warmer springs will increase the rate of cell division within the immature fruit and more, smaller cells will lead to a crisper apple, better able to use the water available to it. Such apples will also last longer after they have been picked. To enhance yields, however, apple growers will have to change their practices to accommodate climatic change, Dr Atkinson warned.

The warmer springs could simply encourage the trees to grow more, rather than putting their energies into developing better fruit. Growers will have to do more pruning and use dwarf rootstocks to keep such vegetative growth under control, as well as providing better irrigation.

Apples are grown commercially by planting a rootstock with particularly desirable growing characteristics and grafting another fruiting variety on to the rootstock. It is rootstock which has attracted the attention of the genetic engineers at Cornell.

Herb Aldwinckle and his university colleagues have inserted a 'foreign' gene into a popular rootstock used in apple orchards. The gene's activity is known to result in damage to the cell walls of bacteria - and fire blight is caused by the bacterium Erwinia amylovora. By transforming the rootstock, the researchers believe that they can confer disease resistance on the plant, without the foreign genes being present in the fruit. This could offer a way round problems of consumer acceptance of foods produced by genetic engineering.