Self incompatibility and genetic divergence in Brassica campestris var. brown sarson

Abstract

The degree of genetic divergence as measured by Mahalanobis's generalized distance ($D^2$ statistic), between twenty-three populations of Brassica Campestris var. brown , was determined in relation to their geographical distribution of six characters related to fitness, namely, days to first flower, number of siliqua on main axis, height, number of primary branches, number of fruit bearing branches and the number of seeds per siliqua, and the divergence between populations was assessed. The populations could be grouped into eight clusters, three belonging to self-compatible (SC) and the rest to the self-incompatible (SI) and confirmed by canonical analysis. Intra- and inter- cluster divergence were parallel with flowering time and height contributing maximum to the divergence. The possible role of disruptive selection in nature and human selection for yield was discussed for the appearance of SC forms in the otherwise self-incompatible brown sarson.