Hybrid seed formation among Dioscorea opposita Thunb. cvs. Nagaimo, Ichoimo, Tsukuneimo, and Dioscorea japonica Thunb.

摘要

Three cultivars, Nagaimo, Ichoimo and Tsukuneimo, of Dioscorea opposita, and 9 lines of D. japonica, were artificially pollinated to observe capsule development and hybrid seed formation. A large number of normal seeds were produced in 7 combinations in D. japonica. Almost all of them contained an embryo (larger than 0.8 mm) which developed into a seedling when sown in soil or cultured in vitro. However, cross incompatibility existed among 4 combinations in D. japonica, and no normal seed was produced. In the crosses Ichoimo X D. japonica and Tsukuneimo X D. japonica there was a difference in the seed-forming capacity depending on the D. japonica line used as the pollen parent. Only a few seeds containing an immature embryo were produced in Ichoimo X Nagaimo, Ichoimo X D. japonica, Tsukuneimo X Nagaimo, Tsukuneimo X D. japonica and D. japonica X Nagaimo. However, in these 5 combinations, some seedlings were obtained by embryo culture. The results of this study suggest that crossbreeding of yam ispossible.