Castor varieties are tall in plant height which makes them difficult for harvesting. A study was carried out to investigate the inheritance of plant height among two tall Castor varieties Hiruy and Abaro and one dwarf experimental line MD-1 during 2012 to 2014 at Melkassa. The F1 from reciprocal crosses of Abaro and Hiruy with MD 1 were all tall. The F2 plants segregated in to 1 dwarf to 3 tall plants and the backcross plants to the tall parents were all tall while plants from the backcross to the dwarf parent segregated into 1 tall to 1 dwarf. The data in this study shows that plant height in castor varieties Abaro and Hiruy is controlled by a single gene at one locus. Dwarf plants appeared at a homozygous recessive condition (ht1ht1) while tall plants can be either homozygous (ht1Ht1) or heterozygous (Ht1Ht1). The results of this study will assist in the breeding for semi-dwarf genotypes of castor varieties in the future.
