Extent and pattern of genetic diversity for morpho-agronomic traits in Ethiopian highland pulse landraces. I. Field pea (Pisum sativum L.)

An experiment was conducted in 2001 at Holetta and Kulumsa, Ethiopia, to study the extent and pattern of genetic diversity in Ethiopian field pea (Pisum sativum L.) landraces. One hundred forty-eight germplasm accessions were grown in an alpha lattice design with 2 replications. Data on 12 traits were collected and analyzed. Differences among the accessions were significant for most of the traits (except number of seeds/ pod) at each location even though differences pooled over location were mostly non-significant. The accessions were grouped into five clusters of different sizes. Accessions from the southern part of the country (Arsi) distributed overall clusters while those from the northern half (North and South Wello, North Gonder and North Shewa) fell into clusters C1 to C3. Cumulative effects of a number of characters dictated differentiation of the accessions into clusters. There was no definite relationship between geographic diversity and genetic diversity as overlapping was encountered in clustering pattern among accessions from different parts of the country. Accessions from different regions might have similar genetic background and those from the same origin might also have different genetic background. Therefore, geographic diversity should not necessarily be used as an index of genetic diversity and parental selection should be based on a systematic study of genetic diversity in a specific population. Genetic distances among most of the clusters were significant that crosses between parents selected out of them are expected to generate desirable genetic recombination. Selection should also consider the special advantages of each cluster and each accession within a cluster. Future germplasm collection, conservation and breeding efforts should focus not only on inter-regional diversity but also on intra-regional diversity.