Electronic Journal of Plant Breeding, 9 (3 ) :1253 - 1257 (Sep 2018) ISSN 0975-928X 1253 DOI: 10.5958/0975-928X.2018.00156.4 Research Note Studies on genetic diversity in rice TGMS lines R. Rahul Roy 1 and D. Kumaresan 2 1. Centre for Plant Breeding and Genetics, TNAU, Coimbatore, Tamil Nadu, 2. Hybrid Rice Evaluation Centre, Gudalur, Tamil Nadu E-Mail: rahulagri15@gmail.com (Received:03 Aug 2018; Revised:17 Aug 2018; Accepted:17 Aug 2018) Abstract One hundred and nineteen rice temperature sensitive genetic male sterile lines (TGMS) were used to study the magnitude of genetic diversity for ten yield traits using Mahalanobis D 2 analysis. Based on Torcher’s cluster analysis, the 119 genotypes were grouped into nine clusters. Cluster I was maximum with 85 genotypes followed by cluster II with 15 genotypes and cluster III with 11 genotypes,. The clusters namely IV, VI, VII, VIII, and IX were solitary clusters with one genotype each. The maximum inter cluster distance was observed with clusters V and IX followed by cluster V and VIII which indicates the genotypes present in these cluster having more divergence. The highest intra cluster distance was observed in cluster III (22.08). Among the traits, number of grains per panicle (49.76 %) followed by number of productive tillers (23.43%), spikelet fertility (14.46%) and pollen fertility (9.93%) exhibited maximum contribution towards total divergence among the genotypes studied. Hence, these characters could be given importance for selection of genotypes for further crop improvement program. Key words Genetic diversity, Rice, temperature sensitive Genetic Male Sterility. Rice (Oryza sativa L), is the most important crop among cereals which is a staple food for 90 per cent of the population in Asia. In India, rice is cultivated in an area of 44 m.ha with a production of 103.41 million tons of paddy and an average productivity of 2.35 t/ha milled rice or 3.52 t/ha rough rice (India Stat, 2012). The present population of 1.22 billion Indians is expected to reach 1.30 to 1.53 billion by 2020 and 2030. So, to support such a huge population, rice production has to be increased by at least 70 per cent over next three decades to meet growing demand Balkunde et al., (2013).With the dwindling cum stagnant agricultural land and water resources, the sought after increase in population will therefore be attained mainly through the enhancement of crop productivity under efficient crop production systems. A plateauing trend in the productivity of the high yielding varieties of rice is a most disturbing trend noticed in recent years. Hybrid rice technology showed the possibilities to increase the productivity with a yield advantage over the best inbred varieties, which in turn generating considerable interest in the adoption of this technology in tropical and subtropical regions of the country (Virmani, 2006). Being a self- pollinated crop, requires the use of a male sterility system to develop commercial rice hybrids mainly based on cytoplasmic male sterility, environment sensitive genetic male sterility and chemically induced male sterility. Currently, CMS is the most widely used method for hybrid rice production with the help of three lines (A, B and R). Even though this system is more viable and reliable, due to its dependence on single source for male sterility (wild abortive) and its cumbersome process, environmental genetic male sterility (EGMS) system has advantage over it, where the male sterility is influenced by environmental conditions (photoperiod/temperature) and the maintainer line is not required. Among the EGMS, temperature sensitive genetic male sterility (TGMS) serves as an efficient and successive tool in development of hybrid rice at tropical conditions (Lopez & Virmani, 2000). TGMS lines have complete pollen sterility at a temperature (>30 ºC/ >24 ºC) at day and night. They revert back to partial to normal pollen fertility at a lower temperature (<24 ºC/>16 ºC). In order to meet the increasing demand of rice, it is important to develop hybrid with high yield potential. The genetic diversity plays an important role to the plant breeder in choosing the right parent (Murty & Arunachalam, 1966). The present investigation was made to study the genetic divergence and clustering pattern in rice TGMS lines for selection of suitable parents for its use in hybridization program and to get better knowledge about the traits contributed for diversity and choice of traits in selection of parents. The experiment was conducted in fertile phase at Hybrid Rice Evaluation Centre (HREC), Gudalur during Kharif 2017 comprised of 119 TGMS lines