Studies on genetic divergence in Gossypium arboreum L. RUMESH RANJAN*, R. S. SANGWAN, S. S. SIWACH, O. SANGWAN, M. SAH AND NANCEE Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar- 125 004 E-Mail : rumeshranjan5@gmail.com ABSTRACT : On the basis of D 2 values, 60 genotypes were grouped into 8 clusters containing 1 to 14 genotypes. These clusters consisted of genotypes with different geographical origins and indicated no correlation between genetic divergence and geographical divergence. The genotypes of cluster VIII showed maximum genetic divergence with cluster I and V. The genotypes belonging to cluster VIII and I may be selected for hybridization for generating genetic variability. Cluster VI found 6 genotypes to be best performing for agronomic characters followed by cluster VIII with 1 genotype and cluster V with 8 genotypes. Thus, to generate desirable genetic variability the crossing between cluster VI, VIII and V genotypes would be useful. It was suggested that hybridization among the genotypes of above said clusters would produce segregants for more than 1 economic character which can serve as parents of hybrids. Days to first flower followed by seed cotton yield/plant, monopods and plant height contribute maximum toward divergence. Key words: Cluster, genetic divergence, G. arboreum, D 2 statistic Gossypium arboreum L. is a native of India. It is cultivated from Punjab in the north to Kanyakumari in the south and Assam in the east to Kutch in the west. G. arboreum genotypes matures between 150 to 180 days and is usually having coarse and short fibre and has high degree of resistance to disease and insect pests and is a very valuable germplasm resource having great export value. It has also been well established that greater the genetic variability in the population, greater will be the chances of obtaining desirable gene combination. Genetic divergence is of considerable practical interest in any crop improvement programme. The wide range in genetic diversity available in India has not been fully exploited to improve the yield. Mahalanobiss D 2 statistic as a tool for estimating genetic divergence in crop plants can be used to choose the parents without making crosses before the initiation of hybridization programme. Therefore, the present investigation was undertaken to study the nature and magnitude of genetic divergence in 60 cotton genotypes. The present investigation was carried out in Research Area of Cotton Section, Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar during kharif 2011. Sixty diverse cotton genotypes from different cotton growing states were collected and raised in a randomized block design (RBD) in 3 replications. There were two rows of each genotype of 3 m length. Rows were spaced 67.5cm apart and plant to plant distance with in a row was 30 cm. The data were recorded on 5 competitive plants selected randomly from each replication. The mean of 5 plants was used for statistical analysis. Recommended package of practices were followed for raising the healthy crop. The data of the 9 parameters were recorded viz, days to first flower, plant h8 (cm), monopods, bolls/plant, boll w8 (g), seed cotton yield/plant (g), ginning outturn (%), seed index (g) and lint index (g). The genetic divergence was worked out by using Mahalanobis D 2 statistic. On the basis of D 2 values, these genotypes were grouped into different clusters by employing Euclidean cluster analysis. The analysis of variance for different traits revealed highly significant differences among the genotypes for all the 9 characters suggested high degree of genetic variability in the material evaluated and specified existence of considerable genetic diversity among genotypes. Hence, further analysis was carried out for relative magnitude of D 2 values for all the characters and all genotypes were grouped into 8 clusters (Table 1 and Fig. 1). Among the J. Cotton Res. Dev. 29 (1) 26-30 (January, 2015)