Parental Backcross Research Articles

Back crossing technique in interspecific hybridization in Gossypium

The theory of back-crossing: Back-crossing is crossing of F.1 hybrid with either of its parents. That parent of the hybrid with which it is again crossed, or with which it is repeatedly crossed is the back-cross parent or recurrent parent the other parent being the donor parent or non-recurrent parent (Knight, 1948) The principle involved in the use of the back-cross technique is the simple one of reducing the amount of genetic variance in the material in which selection is to be practised (Hutchinson et al, 1938). Thus, relatively small population need only be raised to select out the desirable genotype, if back-crossing is resorted, to.

Cytogenetics of Interspecific Hybrids in the Bromopsis Section of Bromus. I. Diploid and Tetraploid Hybrids1

SynopsisDiploid hybrids in the Bromopsis section of Bromus were, in general, morphologically intermediate, but instances of dominance and heterosis occurred. F1 tetraploid hybrids between B. ciliatus and B. frondosus segregated into dwarf, semi‐dwarf, and normal types. Diploid hybrids showed mean bivalent frequencies of 6.50 to 6.79 per MI cell and little irregularity in AI and quartet stages. Mean bivalent frequencies of 12.33 to 12.81 and moderate frequencies of univalents, trivalents, and quadrivalents occurred in MI cells of F1 tetraploid hybrids. Diploid hybrids were highly sterile, but showed slight fertility as seed parents in backcrosses. Tetraploid hybrids exhibited low fertility under open‐pollination.