The sweetpotato improvement program has as objective, the development of genetically improved cultivars with high yield, good storage ability, nutritional quality, high consumer acceptability, disease and pest resistance, and wide adaptability to the different agro-ecologies of Alabama. A major factor contributing to the decline of sweetpotato production in the state is the sweetpotato weevil, Cylas formicarius, as well as virus problems, which cause yield decline in many varieties.
A major effort in the sweetpotato breeding program has been to capitalize on the wide range of expertise at Tuskegee University--plant breeders, biotechnologists, an anthropologist, soil scientist, entomologist/integrated pest management, and a specialist in food processing/product development in the selection of new cultivars. A key aspect in population improvement is the setting up of crossing nurseries. From these new populations intensive selections are conducted in field tests, followed by post harvest evaluation for storage ability and nutritional and overall eating quality. Advanced selections are uniformly tested within regional collaborative trials for at least two years across all sweetpotato growing regions.
Within the framework of the NASA Center for Food Environmental Systems for the Human Exploration of Space, the program continues to break new frontiers by selecting new sweetpotato genotypes, which are adapted to bio-regenerative environments for long term space missions. Several assessment techniques including biotechnology have been adopted to increase the efficiency of screening the genetic resources.
One result of this program has been the release of a sweetpotato cultivar TU-82-155, an early bulking, high yielding genotype with outstanding production traits in controlled environment using hydroponics (nutrient flow technique). High dry matter and high yielding varieties with good consumer acceptance have been identified for future release and for use as elite parents for introgression to improved populations. Students are involved in all aspects of this research program.
Most of the research involves development and improvement of crop plants, alternate systems of production and fertilization that impact the cropping system, soil and water quality. Among the ongoing research efforts are: organic farming using poultry litter and green manure in vegetable cropping systems (Kpomblekou et al., 2002, 2003); timing and use of fertilizers (Ankumah et al. 2000); influence of land use on microbial diversity and soil enzyme systems (Ankumah et al.); use of agriplastics for capturing early markets and for soil solarization to control pests (Stevens et al., 1997, 1998a, 1999b, Khan et al., 2000); effect of cropping practices on water quality (ground and surface water) (Tinsley et al., 2003, Hunter et al., 2004, Liu et al., 2004, Ankumah et al., 2004); nutritional content improvement of sweetpotato varieties (Egnin et al., 2003) improving sweetpotato for nutritional content, disease resistance and wide adoptability, including special environments for long-term space missions (Alvarez et al., 2003); extension of shelf-life and content of post-harvest losses in fruits and vegetables (Stevens et al., 1996, 1997, 1998, 2000) .
A study of Alabama Black Belt counties showed that limited resource farmers produce traditional vegetables (collard greens, bell pepper, squash and turnip) but in limited quantity. The average acreage allocated for vegetables is small because of limited access to market. Vegetable production has a potential as an alternative for traditional crops; however, there is wide variation in annual and seasonal prices. Kebede and Gan (1999) used a linear programming model to assess the economic benefit of vegetable production for small farmers in the Black Belt and showed that it will significantly increase the income of the producers. A study of Kagochi and Kebede (1999) using both linear and quadratic programming showed that vegetable producers have to mix traditional greens with other vegetables having high returns. Both studies suggested that an increase in acreage allocation to vegetable production will increase the farmer’s income. Follow up studies by Alvarez et al. (2003) using plasticulture and improved vegetable varieties have resulted in increased income and rapid adoption. This has allowed farmers to capture niche market share in fresh produce markets in Alabama.