ASSESSMENT OF GENETIC VARIABILITY AMONG NICOTIANA RUSTICA GENOTYPES BASED ON PRINCIPAL COMPONENT ANALYSIS AND CLUSTER ANALYSIS

Abstract

N. rustica is an important cultivated tobacco species that requires cooler climate and its cultivation is confined mainly to the northern and north eastern areas of the India i.e. Punjab, U.P. West Bengal, Bihar and Assam. Rustica tobacco are largely used for chewing, hookah and snuff purposes. ICAR-CTRI is maintaining a large rustica germplasm collection of about 800 accessions and is involved in developing improved rustica tobacco varieties. Genetic improvement of rustica depends mainly on the assessment of variability in the existing germplasm and its utilization. The genetic diversity of the existing rustica germplasm accessions were analysed based on 29 morphological parameters. Initially Principal component analysis (PCA) was done for the identification of morphological characters responsible for diversity. The PCA analysis showed that the genotypes were diverse in nature and the genotypes were scattered around the biplot. Out of 10 PCA components formed based on the eigen values, PCA1 accumulated 32 % of morphological variation loaded on inflorescence shape (IS), inflorescence compactness (IC), inflorescence position relative to upper leaves (IPRUL), flower length (FL), swelling of throat (FST), calyx nature (FCN), corolla shape (FCS), flower expression of tips of corolla (FETC), Flower Colour of Corolla (FCC), Flower Length of Pistil Relative to Stamens (FLPS) and development of stamens (FDS). Based on PCA1, PCA2 and PCA3 seventeen traits showing variation were selected for diversity analysis. The dendrogram showed the genotypes were grouped into four main clusters with many sub-clusters each. Genetic distance between clusters varies from 0.01 to 2.74. The results also showed that Goasani Goan-1, Mohark, M6, NC-64279, SK-49, SR-15 and SR- 29 were exhibiting more diversity when compared to other genotypes. Thus the study indicates that the germplasm was harbouring larger morphological variability which could be effectively used in the rustica tobacco breeding programme.