GENETIC DIVERSITY IN TOBACCO GENOTYPES EVALUATED UNDER ALL INDIA NETWORK PROJECT

Abstract

Tobacco is high valued commercial crop with a steady increase in demand, which needs to be addressed by improvement in yield and quality for meeting national and international requirements. ICAR- Central Tobacco Research Institute and All India Network Project on Tobacco (AINPT) Centres are breeding various tobacco types for higher yield and better quality. The superior genotypes developed are evaluated in AINPT co-ordinated trials at 4 main, 7 sub and 4 voluntary centres. The significantly superior ones are tested in pre-release bulk trials. Diversity in the lines entered in the AINPT trials is essential for releasing varieties with higher genetic potential and reducing the genetic uniformity in tobacco. A study was conducted to investigate the diversity present among entries that were evaluated under AINPT coordinated trials from 2000 to 2015. A total of 100 AINPT lines were used, among which 87 were FCV, 7 Bidi, 4 Rustica and 2 chewing lines. Principal component analysis (PCA) was done to analyze the pattern of data matrix for determining the selection criteria and identification of morphological characters highly responsible for diversity. Based on PCA, 17 characters were selected and analyzed in DarWIN to draw the dendrogram of tobacco genotypes. The entries of FCV, Bidi, Rustica, Chewing fell on four separate clusters. Genetic distance between clusters varies from 0.04 to 2.67. Few Bidi and chewing entries were found to interlay with FCV entries as traits like plant height, plant type, floral morphology, etc., were similar between them. The results also showed that FCV38 has the highest distance from other genotypes followed by ArBD126 with a value of 2.67 and 1.69, respectively. Lower dissimilarity values were observed among genotypes indicating narrow genetic base of breeding programmes. Tobacco breeders, in general, are confined to use less divergent genotypes in order to minimize the disturbance at the genome level. This trend if continued may result in less yield gains in subsequent cultivars and increase vulnerability for biotic and abiotic stress. As bulk of tobacco genetic resources remain unrepresented in modern tobacco cultivars, genetic base need to be broadened through pre-breeding to create variability for further improvement, without quality penalty.