M H Rashid
Senior Scientific Officer
Oilseed Research Centre, BARI, Gazipur-1701
A K M A Islam
Assistant Professore
BSMRAU, Department of Genetics and Plant Breeding, Gazipur
Genetic divergence among 30 genotypes from India, Burma, Bangladesh was estimated using Mahalanobi´s D2 and Rao´s canonical analysis. All together five clusters were formed. The pattern of distribution of genotypes from different geographical location into five clusters was random demonstrating that geographical isolation may not be the only factor causing genetic diversity. Number of bulb per kg onion, leaves length, phosphorus content contributes predominantly towards genetic divergence. Cluster III recorded the highest cluster means for number of leaves per plant, leaves length, bulb diameter, individual bulb weight, dry matter content and for bulb yield. The result obtains from D2 analysis confirmed by canonical analysis.
Onion, Genetic diversity, Multivariate analysis
BSMRAU, Gazipur
Variety and Species
Onion ranks first among the spices crop grown in Bangladesh, both in acreage and production. In addition to its use as spices it is also used as vegetables and salad.
The quantification of genetic diversity through biometrical procedure had made it possible to choose genetically diverse parents for a successful
The present study taken with the following objectives:
 To know the pattern of variability existed in the germplasm.
 To find out better genotypes with better agronomic trait for yield and wider adaptability.
 To evaluate and select the desirable genotypes from collections for future breeding programe.
Seedlings of thirty genotype of onion were raised in 3m×1m-unit bed of thirty seedbeds. Seedlings of 49 days were transplanted in main field in a randomized block design with three replications at experimental field of Bangabandhu Sheikh Mujibur Rahman Agricultural University during rabi season 2006-2007. Each genotype was grown in 10 rows of two-meter length with a spacing of 20cm×8cm. The observation were recorded on 10 competitive randomly selected plants from each plot for nine characters namely number of leaf per plant, leaves length, bulb diameter, individual bulb weight, number of bulb per kg onion, dry matter content, nitrogen content phosphorus content and bulb yield. Plot means over the replications were used for the statistical analysis. Genetic diversity was studied following Mahalanobis (1936) generalised distance (D2) extended by Rao (1952). Canonical analysis was also done according to Rao (1964) to confirm the results of cluster and D2 analysis. Statistical analyses were carried using MSTATC program.
Published paper
No parallel relationship was found between genetic and geographic divergence, which may be due to continuous exchange of germplasm from one place to another. Differently originated genotypes found in same cluster or genotypes from same origin were dispersed in different clusters. It was observed that group IV and I formed with eight genotypes originated in India, Burma and Bangladesh. Group V occupied by three genotypes of Bangladesh origin. There are supportive reports made by Mohanty and Prusti (2002), Mohanty (2001) in winter onion, Mohanty (1999) in kharif onion.
Genotypes from India, Burma and Bangladesh being in different clusters, indicated the broad genetic variability among the genotypes. There was evidence from Shanmugam and Rangasamy (1982) that materials from same origin distributed in different clusters is an indication of broad genetic base of the genotypes belonging to that region.
Considering cluster distance, cluster mean and mean performance of the genotypes for yield, the genotypes G1 and G16 from cluster I, genotypes G12 and G29 from cluster II, genotypes G15 and G30 from cluster III, genotypes G9, G10 and G17 from cluster IV, genotypes G18, G21 and G27 from cluster V may be considered better parents for future hybridization program.
Journal