Hybrid progenies of the cross, Brassica campestris×B. oleracea.

III. Cytogenetical studies on F₂, B₁ and other hybrids

Abstract

Cytogenetical studies on F₂, B₁ and other hybrids obtained from the F₁ hybrids between Brassica campestris and B, oleracea were carried out. The plants examined were classified in three types. The first type plants had 29 chromosomes in root tip cells. The second type plants had 38 chromosomes and the third type plants had other than 29 or 38 chromosomes. Among the first type plants, the range of pollen fertility was 0% to 96.6%, with mean 53.2%, and the frequency of PMCs showing 10_II+9_I, 11_II+7_I and 12_II+5_I were 36.2%, 32.6% and 15.9%, respectively. In the second type plants, the range of pollen fertility varied from 14.0% to 99.0%, with mean 73.6%, and the frequency of PMCs showing 19_II, 18_II+2_I and 17_II+4_I were 71.5%, 17.2% and 7.7%, respectively. The range of chromosome number in root tip cells of the third type plants was 18 to 58 in 33 plants examined, and the range of pollen fertility varied from 0% to 98.0%, with mean 31.8%. Many types of chromosome configuration in PMCs were observed. The possibility of newtype plants of B, campestris, B, oleracea and B. napus was discussed