Published online by Cambridge University Press: 27 March 2009
Exotic accessions of Phaseolus vulgaris selected for seedling cold tolerance by Austin & Maclean (1972) in a test in controlled environments were grown in a field experiment at Wellesbourne in 1974. Yields of up to 4·;7 t/ha at a plant density of 34 plants/m2 were obtained. In 1975, six selected accessions were grown at 21 plants/m2 at six different sites. Mean site yields ranged from 1·0 to 3·1 t/ha. The six accessions all had better emergence and higher yields than two commercial cultivars used as controls. The genotype × site interactions for yield (and for yield components) were small. The variation in yield between accessions (from 2·0 to 2·5 t/ha) was smaller than the variation in yield between sites. Variation in yield components tended to be additive between sites, and compensatory between accessions. There was a negative correlation between crude protein content and yield across accessions; the correlation between protein content and yield across sites was not significant. Accessions differed significantly in the amount of green leaf still attached to plants at harvest. This variation was not related to maturity as judged by moisture content of the seed. There was a negative correlation across accessions between the weight of leaf per plant at harvest and harvest index (the ratio of seed weight to stem weight).