Genetic variability of soybean accessions for yield and yield attributing traits through using multivariate analysis

Abstract

Soybean (Glycine max L. Merril) is the second most important food legume of Nepal, grown either as sole or intercrop with maize or in paddy bund. It has immense potential to increase the area and production due to its yield stability and wider adaptation trait. Its importance increases due to the burgeoning of the poultry and cattle’s farming. Genetic variability is under threat not only in the field but also in the national commodity programs that are meant to be safe heavens. It is the basic requirement for a successful breeding programme. Collection and evaluation of accessions of any crop is a pre-requisite for any programme, which provides a greater scope for exploiting genetic variability. Considering the truths, soybean cultivars were collected from IITA, Nigeria, NAGRC gene bank and local collections studied in depth for morphological characterization using multivariate analyses. An investigation was carried out in the forms of regeneration and observation screening nurseries to assess the variability quantitative traits at Rampur environment and over the years 2012 to 2013. Screening nurseries was carried out in rod row design. Yield and yield contributing traits were analyzed to understand the extent of variability for yield and yield attributing traits. The present study revealed the presence of high levels of variations for nine different morphological traits including yield attributes and seed yield among the soybean accessions. A total of forty diverse accessions of local landraces and exotic lines were evaluated in the subtropical rainfed system of Rampur in the year 2012.Some of high yielding accessions of soybean were 272W, Cobb, G-758, and Puja. Likewise a total of hundred one accessions were evaluated for grain yield and yield parameters during 2013. The research results revealed that high yielding soybean accessions were G-18428, TGX 1990-67F, G-757, V9 (B/pur-9, TGX1990-5F. Under cluster analysis using all the seven morphological traits grouped the 40 accessions into five major groups at the genetic distance of 202.63. It was also found that, among the five clusters, cluster I was the largest and consisted of 32 accessions and the second largest group was the clusters II and IV, and each consisted of three accessions. Likely cluster analysis using all the seven morphological traits grouped the 101 accessions collected from National Agricultural Genetic Resources Centre (Gene Bank) and exotic lines from IITA, Nigeria into five major groups at the genetic distance of 267.82. Among the five clusters, cluster I was the largest and consisted of eighty four accessions and the second largest group was the clusters II consisted of fourteen accessions. The accessions from cluster I and cluster II could be used for hybridization program with the soybean accessions of clusters III, IV and V in order to develop high yielding soybean varieties for further improvement. The first seven principal components were extracted which accounted for about 100% variability among the 104 soybean accessions for all morphological characters. There was rich diversity found in seed coat color of the soybean local landraces. Flower color and pattern of flower were also found diverse among the collected accessions. This study indicated the presence of high levels of genetic variability among the soybean accessions in terms of evaluated characters