Cytogenetic and breeding studies with Brassica II. Progenies from backcrosses involving primary hybrids between B. napus and B. campestris

摘要

The cytological behaviour of backcross hybrids obtained from crosses between the primary hybrid (F1) of B. napus x B. campestris recurrently to B. campestris or B. napocampestris has been discussed. Also discussed are studies made on progenies from selfing the F1 primary hybrid as well as 2n = 22 forms obtained as “segregants” from unstable 2n=20 backcross hybrids. It is thought that it may be possible to establish other numbers such as 2n=32 and 54 and even likely to maintain the tetrasomic 2n=22 types. Observations made on the tetrasomic 2n=22 plants have been used to speculate on certain aspects of the evolution within the subspecies of B. campestris.