A new Raphanobrassica from the cross, 4x-Raphanus sativus L.×4x-Brassica oleracea L.

Abstract

1. A new Raphanobrassica was obtained from the cross between autotetraploid Raphanus sativus L. (Syogoin-daikon) and Brassica oleracea L. (Habotan). The parents were the offspring of autotetraploids induced by colchicine treatment.
2. At the first metaphase of PMC 1_??_7 polyvalents and 0_??_1 univalent were formed in the autotetraploid Raphanus. In the autotetraploid Brassica 2_??_5 polyvalents and 0_??_2 univalents were observed.
3. There is indication of incompatibility in some of the cross-combinations as shown in Table 1.
4. Out of 35 seeds 29 gave rise to mature plants, which were morphologically intermediate (Fig. 2). Cytological investigations were made for 24 individuals which bored flowers. 24 plants had 36 somatic chromosomes and the chromosome configuration at meiosis was 18_II (Fig. 3). One was hypotetraploid (17_II+1_I) and the remaining one was hypertetraploid (18_II+1_I) (Fig. 4).