| International wheat rust testing centre - - Njoro,
Kenya Henry ENNS Plant Breeding Station, Njoro, Kenya The wheats of Kenya are bombarded annually by a particularly wide range of stem rust races, some of which are exceptionally virulent. The rate of appearance of new races of rust has been alarming - particularly during the past two decades. Screening of international nurseries and other collections of wheat has revealed the paucity of material resistant to the races of stem rust occurring in Kenya. In 1961 the Rockefeller Foundation granted special funds to increase the staff and facilities at the Plant Breeding Station, Njoro, in order to try to exploit the rust situation in Kenya in the search for resistance to stem rust. Therefore, a screening program was designed not only to augment the existing wheat breeding program at Njoro, but also to make available to wheat breeders everywhere any resistant material that would be discussed. To date, approximately 11,000 entries from the World Wheat Collection of Beltsville, Maryland, U.S.A., have been screened. Selections from the International Wheat Nurseries and F.A.O. nurseries have been made for many years. In addition, thousands of lines from individual breeders in many countries have been tested. Very fruitful sources of material have been the Rockefeller wheat projects in Mexico and South America. Some of the selections from these various sources have been tested for several years. Although seeds from this station have been sent to many wheat breeders, it is felt that much wider use of the collections could be usefully made. In order to facilitate requests for material and distribution of seed, the collections made by the wheat breeders at Njoro and those derived from this scheme will be arranged in the form of small nurseries. The emphasis will be on rust resistance but several other categories will also be included (paragraph 1 below). The following paragraphs set the kinds of material we have available for distribution and some of our plans to further the search for rust resistance. l. Nurseries. For distribution to interested wheat breeders. (a) Parental rust resistant collection. A collection of 88 wheat varieties which incorporate resistance to various races of stem rust and also exhibit many good agronomic characteristics. (b) Rust Testing Centre Collections. The number will vary with progress. Many will have little but resistance to recommend them. To be used in breeding work. (c) Durum wheat. Resistance and other agronomic features. (d) Earliness. (e) Dwarf. Norin 10 and other sources of the dwarf characteristic. (f) Blotch. (g) Species collection. 2. Further Screening. This will be continued to the extent that wheat breeders can be induced to contribute material for testing. Everything is welcome. 3. Rust Resistance Studies. An attempt will be made to discover the races to which the collected material is resistant and the amount of duplication that exists. Field resistance nurseries and seedling tests will be used. 4. Male-Sterility. Triticum timopheevi type of male-sterility will be used to induce as much intercrossing as possible, using a mixture of the various sources of rust resistance as the recurrent parent. 5. Chemical mutagen. The chemical, ethyl methanesulphonate (EMS) will be used to try to induce rust resistance in otherwise good varieties. The severe rust conditions at Njoro may enhance the chances of success. |