No abstract

Bean production in Central America is mainly a small farm operation on hillside, marginal areas, limited by several biotic and abiotic constraints. More than 350,000 t of beans are produced in nearly 0.5 millions of hectáreas, with a rather low yield average of 678 kg/ha. The majority of bean producers utilize low inputs and few farms are mechanized. Autoconsumption is rather high; however, a great portion of the beans is sold by intermediaries. In Honduras, beans are the 7th most important crop in economic value, and has the highest economic return among corn, rice and sorghum. The major market classes in Central America are small red and black (race Mesoamerican) beans. Improvement of these bean types is focused in developing resistance to diseases (common mosaic, golden mosaic, anthracnose, angular leaf spot, rust, web blight, and common bacterial blight) and pests (mainly pod weevil); and tolerance to low fertility, drought and heat. Appropriate hybridization and selection programs are utilized for developing multiple resistant, high yielding, well adapted and commercially accepted cultivars. A broad genetic base is accomplished by using Andean and Mesoamerican sources of germplasm in the hybridization stage. Simultaneous selection for various traits and multilocation testing of advanced lines are practiced. Yield and adaptation nurseries and trials of improved lines are distributed to Central America, Mexico, Panama and Caribbean countries. Testing of advanced lines and on-farm validation and varietal release, are carried out by National Bean Programs and institutions, members of the PROFRIJOL regional program, in collaboration with Zamorano, CIAT and the Bean/Cowpea CRSP.

In 1994-95, sources of heat tolerance were identified in common beans after screened several germplasm and advanced lines nurseries in Choluteca and Nacaome (≤ 50 masl), in the southern region of Honduras. The best heat tolerant genotypes were validated under greenhouse controlled conditions (35/27 °C day/night) in Geneva, New York. Afterward, crosses were made to develop small-red bean lines with heat tolerance and resistance to BGMV and other limiting factors. The F2- F5 segregant populations were evaluated for multiple traits including BGMV, common bacterial blight, angular leaf spot, rust, low fertility conditions, and selected for agronomic performance and commercial value. In 1998, 217 F6 and F7 advanced lines were evaluated in the irrigation district Lempa-Acahuapa (20 masl), in the Pacific region of El Salvador for heat tolerance and BGMV. The same nurseries were evaluated in Liberia, in the Northwest region of Costa Rica, for tolerance to high temperatures; and at Zamorano, Honduras for resistance to common bacterial blight, angular leaf spot and rust. A group of lines were identified having superior yield and adaptation than commercial checks, under high temperature conditions in El Salvador and Costa Rica. Some of these lines were also resistant to BGMV in El Salvador, and moderate resistant to web blight in Costa Rica, and they had excellent agronomic performance and good commercial value.