Inheritance of Dwarfism in Pigeonpea (Caicmus Caian (L) Millsp.)

Abstract

Inheritance of dwarfism was studied in pigeonpea in Fi> F2» Fg and tostcross generations involving three medium maturing dwarf mutants (Dg, PD^ PBNA), that grow to a height of about a metre and four normal height genotypes: ICPL 1 (Early), BDN 1 (Medium), ICPL 366 and NP(WR) 15 (Late). Growth analyses of Dg and BDN 1 were carried out by taking measurements on non-destructive parameters (plant height, internode numbers, and number of branches) every 12 days, and on destructive parameters (nodulation, and shoot and root dry weights) every 24 days. The results showed that the dwarf mutants had fewer and shorter internodes, and more secondary and tertiary branches than the normal tall plants. The Dg dwarf had lower dry matter production. However, its growth pattern and nodulation was similar to the normal cultivar, BDN 1. The showed that the normal ' plant phenotype was completely dominant to the dwarf phenotype. Dwarfism was inherited as a monogenic recessive trait. The three dwarf cultivars were noted to be mutants at the same locus. Dg and PD^ dwarfs had similar alleles which were designated as tg, while PBNA had different alleles which wore designated as tg>. In crosses among the dwarfs, the tg alleles wore found to be dominant to the tg» alleles. A wide range in plant height was observed for the F2 and F3 generations thus suggesting that environmental conditions and modifiers ware involved in the expression of height.