Studies on F 2 and First Backcross Population of Interspecies crosses (Brassica spp.)

An experiment was conducted at the research farm of College of Agriculture, Nagpur to
determine the nature and magnitude of genetic variability in F 2 and BC 1 F 1 crosses in terms of
various genetic parameters for the different characters. In rabi 2022 three BC 1 F 1 crosses (TAM
108-1 x PC-6) x TAM 108-1, (Kranti x PC-6) x Kranti and (ACN-9 x PC-6) x ACN-9 done for
transfer of powdery mildew resistance from B. carinata (PC-6 donor) to B. juncea varieties and
their three F 2 crosses of TAM 108-1 x PC-6, ACN-9 x PC-6 and Kranti x PC-6 along with their
four parents ACN-9, TAM 108-1, Kranti and PC-6 , were evaluated in RBD with 3 replications.
The data were recorded on days to first flower, days to maturity, plant height (cm), number of
branches plant -1 , number of siliquae plant -1 , 1000 seed weight (g) and seed yield plant -1 (g), and
statistically analyzed. In many of the F 2 or BC 1 F 1 crosses seed yield plant -1 was less though their
number of siliquae plant -1 which was more due to the involvement of two species i.e., juncea and
carinata. Wide range was observed for all the seven characters studied among the three F 2 crosses
and the three BC 1 F 1 crosses. Moderate to high per cent of GCV and PCV were exhibited for plant
height, number of branches plant -1 , number of siliquae plant -1 , 1000 seed weight and seed yield
plant -1 in all F 2 and BC 1 F 1 crosses. High to moderate heritability coupled with high moderate
genetic advance as per cent of mean was exhibited in all the F 2 and BC 1 F 1 crosses except BC 1 F 1
cross (ACN-9 x PC-6) x ACN-9. Selection of potential material were done in F 2 and BC 1 F 1
generation. In F 2 generation, 29 single plants were identified based on the characters seed yield
plant -1 , number of siliquae plant -1 and number of branches plant -1 for forwarding to F 3 generation
by plant to row method for their exploitation. In BC 1 F 1 crosses 64 single plants selected on the
basis of resistance to powdery mildew less than 3 score were backcrossed with their respective B.
juncea parents to get seeds of BC 2 F 1 which will be forwarded to next generation with an aim to
transfer the genetic constitution of B. juncea to improve its yield level.