Electronic Journal of Plant Breeding, 9 (2) : 490-501 (June 2018) ISSN 0975-928X 490 DOI: 10.5958/0975-928X.2018.00060.1 Research Article Assessment of genetic variability for capsule shattering characters in Indian sesame Manasi Dash*, Mohammed Imran, Mandakini Kabi, Bhabendra Baisakh and Devraj Lenka Dept. of Plant Breeding and Genetics, College of Agriculture, OUAT, Bhubaneswar, India E-Mail: manasi_dash@yahoo.com (Received: 19 Sep 2017; Revised: 21 May 2018; Accepted: 06 Jun 2018) Abstract Thirty five Indian sesame genotypes were evaluated for their genetic diversity for seed yield and yield attributing characters as well as capsule shattering characters. The genotypes were classified into eleven clusters, based on Mahalanobis D 2 statistic. Results on inter-cluster distances revealed maximum diversity between genotypes of cluster II and IV. A perusal of the results on cluster means revealed high capsule number per plant, seed weight per capsule and potential seed weight for cluster IV, the earliest genotype possessing maximum branches per plant and retained seed number for cluster VI, while maximum values for plant height, capsule width and thousand seed weight for cluster VIII indicating the desirability of genotypes from these clusters for improvement of respective traits. Further, potential seed weight has the highest contribution to total divergence followed by capsule split before drying, retained seed weight, unattached seed weight and seed weight per capsule indicating their importance in the choice of parents for developing semi shattering genotypes. Key words Sesamum indicum, capsule shattering characters, genetic variability, D 2 analysis Introduction Sesame (Sesamum indicum L.) is one of the oldest oilseed crops grown in India with very high quality oil. It is grown in India round the year covering an area of about 1.67 million ha with an annual production of 0.71 million ton and productivity of 426 kg/ha which is lower than the world production of 489 kg/ha. One of the major reasons for their low yield is that the Indian sesame varieties are mostly of indeterminate growth habit, which flower continuously and bear dehiscent capsules. The plant continues to flower even when the earliest set capsules at the lower portion of the plant are mature which results in non-synchronous maturity of the capsules and seed shattering in the field Weiss(1971) and Ashri(1998). This can be avoided by developing sesame genotypes with determinate growth habit. Although determinate growth habit of sesame was discovered many years ago, it has not been adopted because of many pleiotropic effects associated with the character including severe reduction of plant height, twisted stem and semi sterility Uzun et al.(2013). A few closed capsule mutants were developed earlier to reduce seed loss, but due to difficulty in seed release during threshing the quality of the seed decreases Uzun et al.(2004). On the other hand semi shattering sesame genotypes bearing capsules with higher seed retention capacity will delay opening of mature capsules in the field and release seeds easily on threshing Langham,(1998). Therefore development of semi shattering genotypes with good seed retention capacity at maturity will be useful in maintaining seed quality and help in reducing the yield loss due to capsule shattering in the field. For the development of semi shattering sesame genotypes, the capsule characters related to seed retention need to be identified and analyzed for their effect on seed yield. Genetic improvement of seed yield alone is not possible through phenotypic selection because of its polygenic nature and low heritability. Hence, selection through correlated response entailing several contributing factors influencing seed production shall be most appropriate. Also among the several methods of multivariate analysis available to study the genetic divergence in biological population, the D 2 -analysis Mahalanobis(1936) has been a perfect test in the quantitative estimation of genetic diversity amongst biological populations and assesses the relative contribution of various attributes to total divergence. Genetic diversity studies also help to determine the inherent potential of a cross for heterosis and frequency of the desirable recombinants in advanced generations Raghuwanshi and Duhoon (2005). No information on genetic divergence for capsule shattering characters in sesame is available in the literature. In this context, the present study aimed to characterize the genetic variability in Indian sesame genotypes using Mahalanobis D 2 statistic, based on seed yield and its component characters as well as capsule shattering related traits and to identify promising parental lines for their use in developing semi shattering genotypes. Materials and Methods Experimental material for the present investigation comprised of thirty five sesame genotypes screened for capsule shattering characters at the