1Botany Department, Faculty of Agriculture, Zagazig University, Zagazing, Egypt.
This investigation was carried out to study the genetic behaviour of days to heading and tillering capacity in some induced dwarf, semi-dwarf and early rice mutants derived from the local rice variety "Nahda". These mutants along with three varieties and their various filial generations derived from crosses among them were studied. Transgressive segregation in both directions for earliness and lateness in some crosses was observed. Dominance effect was positive in some crosses and negative in others. Partial dominance towards lower tiller number was detected. Dominant gene action prevailed in the control of these characters. Duplicate type of epistasis was observed for both characters in most of the crosses studied. Genes controlling dwarfness seemed to be not associated with those governing earliness.
