Approaches are needed to broaden the genetic base and improve earliness and yield potential of large-seeded beans under sustainable cropping systems. The objective of this research was to develop adapted dwarf bean populations having a commercial seed quality and yield suitable for the production in the South of Europe. The original base populations were produced from crosses between genotypes within each Mesoamerica, Nueva Granada and Peru races, and between Peru and Nueva Granada, and Mesoamerica and Nueva Granada races. Visual mass selection for plant performance was practised in the F2 and F3 generations. In the F4 and F5, single plants were harvested under two cropping systems (sole cropping and intercropping with maize). From F4, selection was based on precocity, combined with seed yield and seed commercial type. The F4:7 selected lines from each original population were compared with their parents and five checks at four environments and two cropping systems. Differences among environments, populations, parents and checks were observed for all traits. Under intercropping with maize, there was a 50% reduction in seed yield. Yield of parents and checks belonging to Andean South American races, intraracial (Nueva Granada × Nueva Granada) and interracial (Nueva Granada × Peru) populations, was higher than that of those of Middle American origin. Intraracial crosses within large-seeded Andean South American (Peru race) and Middle American gene pools (Mesoamerica race) did not produce lines yielding more than the highest yielding parent. Only two large-seeded lines selected from crosses between small- and large-seeded gene pools out-yielded the best parent and check cultivar.

Research was supported by a Plan Nacional I+D+I (AGF93-0756-C02) and Xunta de Galicia (INFRA91-015) projects from the Spanish Government. The authors are grateful to the Diputación de Pontevedra and A.P. Rodiño for farm facilities and Lidia Otones for technical assistance. A.B. Monteagudo, A.M González, A.P. Rodiño and M. Lema acknowledge fellowships from the Xunta de Galicia, CSIC and Diputación de Pontevedra, that allowed them to carry out this study. Special thanks to J.D. Kelly for anthracnose, S.P. Singh for BCMV and BCMNV, M.A. Pastor-Corrales for rust and C. Asensio for bacterial inocula.

Diputación Provincial de Pontevedra

Xunta de Galicia

Peer reviewed

MCYT

CSIC