VARIATION FOR CROSSABILITY IN A RECIPROCAL, INTERSPECIFIC CROSS INVOLVING HORDEUM-VULGARE AND H-LECHLERI

Several crossing series including the hexaploid (2n = 6x = 42), South American species Hordeum lechleri and diploid (2n = 2x = 14) cultivate d barley (H, vulgare) were performed. Barley functioned better as the paternal than as the maternal parent in all cases. Viable offspring we re only obtained from one hybrid combination when barley was used as t he maternal parent. There was an environmental influence on the succes s of crosses. A high seed set was counteracted by a lower germination frequency. The outcome is that different crossing series give similar results. As a result of chromosome elimination and in a few cases dupl ication of especially the barley chromosomes, the chromosome numbers o f the offspring (239 plants) varied from 2n = 21 (trihaploids of H, le chleri) to 2n = 30. Fifty-five % of the plants were euploid with the n umber expected for a hybrid (2n = 28). The frequency of hyperploids, e uploids, hypoploids (2n = 22-27) and trihaploids varied by year, local ity, type (winter/spring) of barley, H. lechleri population, and cross ing direction.