Genetic Improvement of Common Bean, Challenges, and Future Prospects.

Genetic Improvement of Common Bean, Challenges, and Future Prospects

Shree P. Singh

University of Idaho, 3793N 3600E, Kimberly, ID 83341

For sustained genetic improvement of crops a periodic review of progress made, challenges faced, and prospects and strategies for future improvements is essential. My objectives are to review (1) major events that shaped common bean breeding and genetics, (2) yield improvements achieved, (3) impacts realized with emphasis on the American continents, (4) challenges facing, and (5) future prospects and strategies for improvements. Deciphering origin, domestication, and organization of genetic diversity was a milestone. Growth habit, maturity, and seed size are associated with yield such that cultivars of different evolutionary origins, gene pools, and races have different yield potential. Tropical and sub-tropical germplasm are not adapted to North America. Yield increased by 45% in race Mesoamerica by changing from early maturing determinate Type I to tall late maturing indeterminate growth habit Type II cultivars. Yield improvement of 35% was obtained by increasing biomass yield and/or harvest index and delaying maturity in race Durango cultivars. Improvement in race Nueva Granada has been in resistance to diseases. Yield improvement in races Guatemala, Jalisco, Chile, and Peru has been negligible. Impact of genetic improvements in races Durango, Mesoamerica, and Nueva Granada on the American Continents and elsewhere will be reviewed.  Increasing yield of Type I Nueva Granada, Type II Durango, and within the same seed size, growth habit, and maturity class of cultivars of any gene pool and race offers a daunting challenge.  Use of high yielding genotypes with positive general combining ability, broad based populations, and gamete selection using molecular markers and direct screening combined with early generation yield tests should be considered for integrated genetic improvement of yield, seed quality, plant type, maturity, and resistance to biotic and abiotic stresses in common bean.