PESTS, disease and climate change could result in future generations being deprived of enjoying chocolate treats. Now, scientists and biologists at a UK university are leading the world's challenge to ensure the sustainability of cocoa production.

Today, pests and diseases destroy about a third of potential cocoa production and, if serious climate change takes place, experts predict there will be a greater threat to future supplies of cocoa.

Cocoa provides pleasure to billions across the globe by giving us chocolate and chocolate products in many forms. But it is also vital to the economies of established cocoa-growing countries in West Africa, as well as offering potential export earnings to places new to cocoa growing such as Vietnam and Tanzania.

With funds for a new five-year project to assess the threat that climate change poses to cocoa growing, the University of Reading, southern England, is now in a unique position to examine all three main risks to the crop.

The crop's production faces significant problems from increasing global temperatures and more varied rainfall. Using a state-of-the-art cocoa physiology glasshouse, Reading University researchers seek to help to develop new cocoa varieties better suited to possible future climates.

The glasshouse has six independently controlled compartments, each capable of growing mature, pod-bearing trees.

Each compartment has supplementary lighting, moveable shade screens and a central computer control system that can be used to simulate specific cocoa-growing regions representative of present and predicted future climates within the regions.

Cocoa is one of the most important sources of income for many countries in the humid tropics. Together, Ghana and the Ivory Coast produce nearly 70 per cent of the world's supply.

For Ghana, where it is grown by smallholder farmers, the crop accounts for more than 40 per cent of export revenues and two million people are involved directly or indirectly in its production.

There are four postdoctoral research fellows and eight research students working on the cocoa project at Reading. Many of the research students have come from cocoa-producing countries.

Professor Paul Hadley, from Reading University's School of Biological Sciences, is leading the research project. He arrived at Reading in 1977 as an overseas development administration research fellow and was appointed as lecturer in horticulture in 1981.

His research has focused on the crop physiology of temperate and tropical crops and he has worked on cocoa for more than 25 years. His interests in the crop include the effects of environment on the growth and productivity of cocoa and conserving the genetic resources of the plant.

Professor Hadley said: "There is now a broad agreement that future climate change as a result of increased greenhouse gases and deforestation is likely to lead to challenging climatic conditions for almost all crops. Particular challenges for tropical crops are likely to include less evenly distributed rainfall patterns and higher maximum temperatures.

"With little or no research being carried out on the effects of climate change on cocoa, the new project highlights the university's importance to the crop's future. Our project aims to devise long-term strategies that will be required to breed new cocoa varieties which are better suited to climates likely to exist in the future," he added.

The International Cocoa Quarantine Centre (ICQC) that handles all international movement of cocoa breeding material is also based at the university and is the only facility of its kind in the world. It houses a collection of more than 350 genetically distinct cocoa trees, with a further 100 passing through quarantine.

The movement of cocoa germplasm is often essential in providing material for crop improvement programmes but is also associated with the risk of spreading pests and diseases.

Intermediate quarantine can minimise this risk. The quarantine procedure lasts for two years, during which time the trees are indexed for pests and fungal and virus diseases.

The ICQC is playing a pivotal role in stopping the spread of pests and disease on cocoa, while ensuring that research centres worldwide have access to new and interesting types of cocoa.

Breeders and researchers working on cocoa material can find crucial information on this through the university's International Cocoa Germplasm Database (ICGD) project that was started in 1988.

The ICGD contains information on 28,000 characterised trees, such as disease-resistance characteristics, and is at the forefront of this area for nearly all tropical tree crops.