Breeding for protein in the bean (Phaseolus vulgaris L.): I. Inventory of some Brazilian varieties and a number of lines of differing origin

Observations of some of the Brazilian bean varieties in the field as well as in the laboratory have shown that the general characteristics of these varieties do not deviate appreciably from wild beans, indicating that comparatively little breeding has been applied. Selections have therefore been initiated to improve productivity and protein content and quality. The present study represents the initial steps in determining the existing range of variation between and within several of the commonly grown varieties. A screening of some hundred bean lines of different origin was also undertaken to establish if in this material the range of protein content was appreciably larger. The average protein content of 8 varieties was 24% (22.7-26.7%), of a single plant 23% (16.7-31.9%). A genetic background, and therefore selection potential was indicated in at least 3 varieties: Carioca, Pirata and Rico 23. Analyses of 3 small collections totalling 201 lines had an average content of 24.3% (14.1.-35.8%). Bulked seed from each variety showed a lysine content of 6.7% (4.9-7.3%) and of 0.7% (0.6-0.8%) methionine. A 3-stage programme for improving protein content of Brazilian varieties is outlined