Electronic Journal of Plant Breeding, 5(4): 781-785 (Sep 2014) ISSN 0975-928X http://sites.google.com/site/ejplantbreeding 781 Research Note Assessment of genetic diversity in pigeonpea germplasm collection using morphological characters K. Rupika* and J. R. Kannan Bapu Department of Pulses, Tamil Nadu Agricultural University, Coimbatore-641003,Tamilnadu, India. *Email:rupi.agri@gmail.com (Received: 23 July 2014; Accepted: 12 Aug 2014) Abstract An investigation was undertaken to ascertain the extent of genetic diversity present among 90 pigeonpea genotypes using D 2 statistic. Cluster analysis grouped 90 germplasm into six clusters based on the degree of divergence between the genotypes. Clustering pattern revealed non parallelism between genetic diversity and geographic distribution. Inter cluster distance was least between cluster II and cluster III and cluster I and VI, indicating less divergence in these four clusters. Maximum inter cluster distance was noticed between the cluster V and cluster VI, cluster IV and cluster VI, cluster II and cluster VI and cluster I and cluster V, indicating more divergence of cluster V and this cluster had five genotypes viz.,C -2291, ICP7234, ICP12225, AL1741, ICP2391. Accessions of cluster V were more divergent with maximum intra cluster distance followed by cluster I. The crossing between cluster V which is having high cluster mean value for seed yield per plant and number of pods per plant and cluster II which is having lowest mean for days to 50 percent flowering is expected to yield high yielding early pigeopea varieties. Morphological characterization was carried out for nine traits, some of the genotypes had unique characters which helps in varietal or genotype identification. Key words: Pigeonpea, genetic diversity, germplasm Pigeonpea (Cajanus cajan (L.) Millspaugh) (2n = 22) is the second most important pulse crop of India after chickpea, commonly known as arhar, redgram and tur. Pigeonpea is a grain legume belonging to the Cajaninae sub-tribe of the economically important leguminous tribe Phaseoleae. Based on the natural genetic variability in local germplasm and the presence of numerous wild relatives, Van der Maesen (1990) concluded that India is probably primary centre of origin. Pigeonpea is an important pulse crop that performs well in semi-arid tropics where moisture availability is unreliable or inadequate (Reddy et al., 1993). India is the largest producer of pigeonpea in the world sharing approximately 70% of the production and covering 74% of the area (Bohra et al., 2012). Pigeonpea occupies an area of about 4.04 million hectares in India with a production 2.65 million tonnes, with a productivity of 656 kg/ha (INDIASTAT, 2012). Although India leads the world both in area and production of pigeonpea, its productivity is lower than the world average. One of the factors responsible for the poor productivity of pigeonpea is the lack of improved cultivars. Research for genetic improvement of this crop is required to raise yield levels effectively through widening genetic base. The experiments for the present study were conducted in the Newrea, Department of Pulses, TNAU, Coimbatore during Kharif 2013. The experimental material comprised of 90 pigeonpea germplasm. The experiment was laid out in Randomised Block Design with two replications. Observations were recorded for eight quantitative traits. They are days to 50 % flowering, days to maturity, plant height, number of primary branches per plant, number of pods per plant, number of seeds per pod, hundred seed weight and seed yield per plant. The quantitative measurement of genetic divergence among the genotypes was carried out by Mahalanobis D 2 statistic (Rao, 1952). The observations on nine morphological characters were recorded in the form of multiscale scores. The scaling adopted as per the International Bureau for Plant Genetic Resources (IBPGR)’s descriptor (IBPGR, 1993) on pigeonpea. The genotypes included in the present study were from the different sources and were grouped into six clusters (Table 1). Cluster I was the largest with eighty one genotypes followed by cluster V and other clusters possessing one genotype each. Clustering patterns indicated that the genotypes originating from different geographical regions grouped together into different clusters. This non parallelism may be due to genetic drift and intense natural and human selection for diverse adaptive gene complexes under different environments causing greater diversity among genotypes rather