Relationship between genetic distance and heterosis for yield and morphological traits in winter canola (Brassica napus L.).

Genetic distance among canola cultivars was estimated through multivariate analysis. Thirty cultivars from various sources were analyzed and clustered based upon five morphological characteristics and yield components-crown diameter, number of branches plant(-1), number of pods plant(-1), number of seeds pod(-1) and yield plant(-1) -and placed in three distinct clusters. Two cultivars from each cluster were selected as parents and 15 partial-diallel inter- and intra-cluster crosses were made between the six selected parents and evaluated at two locations in Michigan in 1990/1991. The association between genetic distance and mid-parent heterosis was investigated. The correlation between genetic distance and heterosis was positive and highly significant for seed yield, number of pods plant(-1), and number of seeds pod(-1). Clustering, based on yield and yield-component traits, demonstrated that inter-cluster heterosis was greater than intra-cluster heterosis in the majority of cases.