Six pea (Pisum sativum L.) varieties, fifteen F₁ hybrids and their reciprocals were used in this study as a source of variations to detect the performance and evaluate the variability and genetic architecture of some developmental and physiological characters during the seasons of 1997/98 and 1998/99 . All the studied characters are largely determined by genes with dominant effects and to some extent by genes with additive effects except stem length and DNA content which were found to be determined by both types of gene effects. Dominance with asymetrical gene distribution is suggested to be present in the parental genotypes for number of leaves and number of branches per plant, stem and leaves dry weight and RNA content. Dominant factors are responsible for determining the low expression of stem length while these dominant factors are found to be responsible for the high values of stem and leaves dry weight, DNA and RNA content. Meanwhile, ambidirectional dominance is suggested for both number of leaves and number of branches per plant. Non-independence of gene distribution among parents is observed for stem length, number of leaves and number of branches per plant, stem and leaves dry weight. In addition, non-allelic interaction of the complementary type is suggested for all the studied characters except for stem length. A close association of dominance with high values was observed in Mammoth and Arica for both stem and leaves dry weight and in Mammoth, Little Marvel and Hunter for RNA and DNA contents.