Inheritance of Biomass Yield and Tropane Alkaloid Content in Hyoscyamus muticus

The nature of gene action for biomass yield and tropane alkaloid content was ascertained through diallel analysis in Egyptian henbane, HYOSCYAMUS MUTICUS L. Dominance variation was preponderant over additive genetic variance, dominance being in the overdominance range for both traits. On an overall basis, recessive alleles had a positive (i.e. increasing) effect on both the characters. However, the positive or negative effects of recessive or dominant alleles were genotype-specific. Hence, transgressive breeding was suggested for isolating segregants with dominant alleles for herb yield and with recessives for alkaloid content so as to achieve overall high yields of tropane alkaloid per unit area.