INDUCED POLYGENIC CHANGES OCCURRING SIMULTANEOUSLY WITH MAJOR GENE CHANGES IN BLACK HENBANE (HYOSCYAMUS-NIGER L)

Two macromutants [unbranched (Ub) and restricted branched (Rb)], one point mutation [yellow flowerd ('Aela')] and two flowering variants (early and late) were isolated in the M2 generation of gamma-irradiated progenies of black henbane (H. niger) - a medicinal plant belonging to family Solanaceae. These major gene changes were coupled with simultaneous changes in several polygenic systems conditioning continuous variation for flowering time, plant height, numbers of shoots and leaves, biomass and crude drug content. Such quantitative variation in qualitative mutants were measured for both per se means and cross-bred performance in terms of. (1) shifts in univariate means, (2) changes in pooled divergence, (3) alterations in gca effects, and (4) changes in heterotic capacity. The mutants were significantly divergent from the parental base for all the six metric traits, both individually as well as collectively. Divergence among mutants was wider (D2 = 1491 to 11 469) than that for mutants versus source parent (D2 = 117 to 7120). Conspicuous alterations in both the nature and the magnitude of the gca effects associated with all mutants, except L-2013 (late flowering), relative to the parental base were observed for all of the metric traits examined (gca congruent per se means). Similarly, the mutants manifested greater heterotic potential than the parental base. This is even more strongly reflected in mutant x mutant hybrids for all of the characters. The amount of economic heterosis for diverse traits followed the pattern: crude drug > biomass > flowering time congruent-to plant height > number of shoots congruent-to number of leaves.