Studies on the floral traits and their implications on pod and seed yields in bambara groundnut [Vigna subterrenea (L.) Verdc]

摘要

Two field experiments were conducted in April and August, 2007 at the Department of Crop Science Research Farm, University of Nigeria, Nsukka to evaluate the floral structure of thirteen cultivars of bambara groundnut. The result showed that the differences between the two planting dates were significant for all the traits measured except for stigma diameter. Interaction of cultivars and planting dates had significant effect on pistil length, stamen length and stigma- anther separation. It is evident from the results obtained that exploitable variations existed among the cultivars. The principal component analysis revealed that the first three principal components contributed 83.90% and 84.28% of the total variability for the early and late plantings, respectively. It also showed that cultivars were differentiated on the basis of anther diameter and seed weight per plant during the early planting and, stamen length and number of pods per plant in the late planting in the PC1. Cultivars were differentiated by pistil length for the early planting and anther length for the late planting along the second principal component axis. The cluster plots grouped the 13 bambara groundnut cultivars into two clusters in both early and late planting dates. In the early planting, clusters I and II comprised five cultivars each. The cultivars in cluster I are associated with long pistil and stamen with lower stigma and anther diameters values while cluster II cultivars are characterized with high number of pods per plant, high seed weight per plant, very marginal stigma-anther separation and high anthers and stigma diameters. During the late planting, the cluster I consists of seven cultivars with large stigma diameter, longer pistil and stamen with larger stigma- anther separation. The cluster II consists of five cultivars characterized with large anthers, marginal stigma-anther separation and higher number of pods and seed weight per plant. Seed weight and number of pods per plant were significantly correlated with anther diameter. However, seed weight per plant was negatively correlated with stigma- anther separation (r = -0.59**) implying that seed weight per plant increased with decrease in stigma-anther separation.