INHERITANCE AND LINKAGE STUDIES IN COWPEA (VIGNA UNGUICULATA (L.) WALP.)

Abstract

Inheritance and linkage relationships of growth habit, seed size, stipule colour, and stem pigmentation were studied in a cross involving cv. Selection-2 and K. 11 of cowpea. A trigenic ratio of 39:25 was observed for growth habit of which one is the basic gene, and the other two are inhibitory and antiinhibitory genes. Large seed size and red stipule colour were monogenically dominant over small seed and green stipule, respectively, with a good fit of 3:1 ratio in F2. A complementary digenic ratio of 9:7 was observed for stem pigmentation. The following gene symbols are proposed: growth habit (Vi-I, Vi-2, Vi-3), big seed (Ug), stipule colour (Sm, and stem pigmentation (Pp-l, Pp-V. Joint phenotypic segregation studies revealed that the basic gene for growth habit is linked with the dominant gene for seed size with a crossover value of 46%, whereas 17.4% crossing over was observed between one of the complementarygenes for stem pigmentation and the gene for stipule colour.