Based on reports contributed by Raymond Nance, Paisan Loaharanu, Felipe Zapata, Martyn Jeggo, and other staff of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture
Research in agricultural fields keeps advancing in the 1990s, and IAEA and FAO scientists working with counterparts worldwide are contributing in important ways.
About ten years ago, scientists realized that a nuclear-based diagnostic technique - enzyme-linked immunosorbent assay, or ELISA - could overcome many technical problems and be effectively applied for nearly all major diseases affecting livestock in developing countries. In the 1990s, the Joint FAO/IAEA Division developed methodologies and approaches for transferring ELISA technologies efficiently. Standardized and validated kits tailored for the developing world now are used by authorities in seventy countries, including many engaged in an intensified global campaign against rinderpest, or "cattle plague". The ELISA technique today is a key management tool to monitor progress in support of other animal health campaigns worldwide: foot-and-mouth disease, which has been eradicated from Europe, Indonesia, and Uruguay and is being wiped out in the Americas; brucellosis, where a blueprint now exists for its eradication across Europe and Arabia; trypanosomosis, nearing eradication in Zanzibar and now targeted for elimination in parts of Ethiopia.
SOIL & WATER
About two-thirds of all river water is used for agriculture, and scientists are looking closely at how to achieve more with less. Through IAEA-supported research, they are studying a practice called "deficit irrigation" using neutron probes to investigate and evaluate soil moisture and crop water requirements. So far, some positive results have been seen. In Argentina, researchers found that cotton growers could achieve high yields by using half as much water during the vegetative and flowering stages, and no irrigation whenever the soil moisture content is ninety percent or higher. In Brazil, irrigating with half as much water at certain growth stages netted higher yields for bean and corn crops. In Morocco, the technique was applied to develop better water management schemes for sugar-beet and wheat.
Through work of the IAEA's Seibersdorf Laboratories, the radiation-based sterile insect technique (SIT) has become the bane of pests ravaging crops and threatening animal and public health. Over the past decade, working through global research networks, scientists have zeroed in on biotechnological approaches to improve the applicability and effectiveness of the technique against fruit flies, specifically the Mediterranean fruit fly, or Medfly. They now have developed a genetic technology designed to optimize the rearing of male flies and reduce the overall costs of applying SIT in the field. In other research, scientists recently recorded the first confirmed case of genetic transformation in the Medfly, a breakthrough that offers the chance to develop strains of the species that can be more effectively and economically used for insect control campaigns incorporating SIT.
National laws and global trade agreements require food to be free from contaminants that provide unacceptable risks to human health, and in more and more cases, consumers also are demanding that the food they buy causes no undesirable environmental effects. Taken together, these developments have intensified research to monitor food, water, and other environmental materials for chemical contaminants (including biotoxins), and in the case of food, pathogenic microorganisms as well. Easy to see is that the number of analyses is enormous. Conventional methods usually require expensive equipment and reagents, and they are time consuming. Now being more closely looked at is the use of immunoassays as screening methods for organic contaminants, such as pesticides, which offer advantages in terms of costs and time for analyzing large numbers of samples. But the method holds disadvantages as well, and scientists involved in IAEA-supported research are examining technical factors affecting potential applications, as well as potential costs. In the case of pesticides, the cost of developing an assay is about $100,000. Nevertheless, kits for over thirty pesticides are now commercially available that in some cases show a cost saving of three hundred percent compared to one alternative method. Another potential screening tool widely used in other fields, thin layer chromatography, or TLC, is gaining a fresh look for monitoring pesticide residues from advances in biotechnology. Methods have been developed that adequately check if a foodstuff complies with international food safety requirements, and scientists in twelve countries now are evaluating the methods under a newly started research project.
Known as plant or crop breeders, scientists have tried since civilization began to develop and cultivate the world's crops, numbering about 80,000 edible plants today. It's a hard job: after centuries of painstaking work, less than thirty species, but thousands of varieties, provide nearly all the world's food. Over the past decade, DNA probes and related molecular biological methods, combined with mutation techniques and diagnostic radioactive isotopes, particularly have quickened the pace through greater understanding of plant variations. Laboratories in developing countries are engaged in work through an FAO/IAEA programme that facilitates the transfer of DNA probes and methods. Advances in using radiation-based techniques also keep being recorded. One technique now is used to develop varieties of date palm resistant to Bayoud disease in Algeria, Morocco, and Tunisia where fifteen million trees have been killed by the fungal pathogen. As a result of research combining induced mutations, conventional breeding techniques, and biotechnology, new varieties of linseed, rapeseed, soybean, and sunflower are becoming commercially important. Two new varieties of linseed were registered in Canada in 1993 and 1995. Over recent decades worldwide, scientists at the Agency's Seibersdorf Laboratories have irradiated about 22,000 samples of seeds, vegetative materials, and in vitro cultures that were sent to laboratories in over 100 countries, including seeds used for molecular biology research. Worldwide, over 1800 mutant varieties of crops and plants have been developed, most of them using radiation-based techniques.
Research over the past ten years has more firmly demonstrated that the technology of irradiation is safe and effective for ensuring the hygienic quality of food, especially products such as chicken, seafood, meat, and spices. Recent advances have enabled its application as a quarantine treatment of fresh fruits and vegetables against insect pests; research was jointly sponsored by the IAEA, FAO, and World Health Organization. National and international food regulatory bodies have moved in the 1990s to endorse irradiation, issuing standards and policies governing its wider application. A major breakthrough came in May 1996. The United States Department of Agriculture accepted irradiation as a quarantine treatment against fruit flies in fruits and vegetables, enabling national trade from Hawaii to mainland states of papaya, lychees, and other commodities. The action is heightening interest in the technology among developing countries seeking expanded global markets for their products.