LOS BAÑOS, Philippines (dpa) – Sigrid Heuer is doing her bit to help feed the world. The 43-year-old German molecular biologist breeds new rice varieties, which can survive boiling heat, floods or exhausted soils.

Rice is the main foodstuff for 3 billion people, 90 percent of them in Asia. The International Rice Research Institute (IRRI) in Los Baños in Laguna province works on the front line of agricultural crop research, as climate change threatens millions of hectares of farmland.

A rice variety developed by IRRI that is capable of surviving floods has just been approved for release in the Philippines and parts of India, a success for the research center and the result of 20 years' development work by the scientists.

Heuer contentedly surveys her research paddy outside IRRI's headquarters located at two-hour drive south-east of Manila. Twenty plots are set up on a 5-by-20-meter field grid. The scientist grows different rice varieties, with and without the submergence1-gene variation, or Sub1, which ''waterproofs'' the plants.

"We flood the paddy for two weeks, then you see the difference," Heuer said, pointing out some plots where hardly any plants survived after being totally submerged, while the rice varieties containing the flood-resistance gene prosper.

"What we are doing is a mix of classic plant breeding and new technologies," Heuer explained. The submergence- tolerant gene variant was found in a certain Indian rice variety in the lab, isolated and then interbred with the high-yield variety IR64, also developed by the IRRI.

"With DNA analysis we can determine whether the gene is present or not. That speeds up the process and makes it more precise. The DNA analysis saves us a whole growing season,'' she said.

Every year, 10 to 15 million hectares of rice-growing land are flooded, leading to the loss of crops worth around 1 billion dollars.

"Sub1 can help millions of farmers," Heuer said. This new method for breeding crops is known as marker-aided selection and makes the process of developing new varieties easier.

IRRI, a non-profit organization, does not register patents for its rice breeds.

"Rice is being farmed in coastal regions and river deltas, like Bangladesh, Myanmar and Vietnam,'' said biologist Reiner Wassman, who coordinates the IRRI's climate change research. ''If ocean levels rise, it affects rice more than any other crop. More people are dependent on good rice harvests than any other grain."

However, arable land has to make space for construction and demand for rice has been higher than the harvests for many years. Crop failures caused by heat, drought or floods are additional catastrophes. Farmers urgently need new rice varieties so that they can continue to produce profitable harvests in spite of changing climatic conditions.

Rice flowers turn sterile if they open in temperatures higher than 36 degrees Celsius and therefore cannot produce grains. Most breeds are biologically tuned to open their flowers in the late morning. ''We are now looking for varieties that open in the early morning, when temperatures are still lower,'' Wassman said.

In greenhouses on IRRI's 250-hectare research facility the scientists also simulate higher night-time temperatures. ''We have a correlation between higher night-time temperatures and lower yields,'' Wassman said. Now the question is whether there are rice varieties that are able to better withstand those higher temperatures.