Journal of Natural Sciences Research www.iiste.org ISSN 2224-3186 (Paper) ISSN 2225-0921 (Online) Vol.5, No.9, 2015 11 Grain Yield Based Cluster Analysis and Correlation of Agronomic Traits of Sesame (Sesamum indicum L.) Genotypes in Ethiopia Fiseha Baraki 1* Yemane Tsehaye 2 Fetien Abay 2 1.Crop Research Core Process, Humera Agricultural Research Center, Ethiopia 2.Department of Crop and Horticultural Science, Mekelle University, Ethiopia *Corresponding Author Email: fish051bar@gmail.com Abstract The experiment was conducted in the western Tigray region of Northern Ethiopia in three locations and three growing seasons (a total of seven environments). The objective of the study was to assess the interrelation ship of the genotypes in their grain yield and other agronomic traits. The experiment was laid out in RCBD with a total and harvestable plot size of 14m 2 and 10 m 2 respectively. In the experiment a total of thirteen sesame genotypes were used and evaluated for the interrelation ship of their grain yield and other agronomic traits. Based on their grain yield the thirteen genotypes were grouped in to four clusters and the maximum genetic divergence (D 2 = 215.57) was observed between cluster-II and cluster-III. Grain yield had a significant and positive correlation (P<0.01) with oil content (r = 0.79), number of branches (r = 0.7) and number of capsules (r =0.68). In contrast to this, yield was negatively correlated with days to maturity (r = -0.58 ) and days to flowering (r = -0.11). Exhaustive assessment of the association of grain yield and other agronomic traits is indispensably important for further breeding program and enhancing grain yield of sesame. Keywords: Cluster, Correlation, Genotype, Grain yield 1. Introduction Sesame (Sesamum indicum L.) which is also commonly known as til (Hindi), hu ma (Chinese), sesame (French), goma (Japanese), gergelim (Portuguese) and ajonjoli (Spanish) (Anilakumar, et al., 2010) is an annual plant that belongs to the Pedaliaceae family. Sesame is mainly cultivated between the 25° N and 25° S latitudes. Despite its ideal adaptation to dry sites, sesame can also be cultivated in humid, tropical and sub-tropical regions (Natureland, 2002). It is an erect herbaceous annual plant with either single stemmed or branched growth habits and two growth characteristics of indeterminate and determinate, reaching up to 2m height and with a large tap root of up to 90 cm (Ashri, 2007). According to Kobayashi, et al. (1990), 36 species have been identified under the genus Sesamum with three cytogenetic groups 2n = 26, 2n = 32 and 2n = 64 from which the widely cultivated Sesamum indicum is within the first group. Ethiopia is the Sixth largest sesame producer in the world following Myanmar, India, China, Tanzania and Uganda, respectively and third in Africa preceding Nigeria and Mozambique, respectively (FAOSTAT, 2012). Within Ethiopia, the Tigray region is the main producer with large commercial farms and many small scale farmers and it is a good source of income in these areas using as a cash crop and local oil extraction. Cluster analysis aims to classify a sample of subjects (or objects) on the basis of a set of measured variables into a number of different groups such that similar subjects are placed in the same group (Cornish, 2007). Ward's method is distinct from all other methods because it uses an analysis of variance approach to evaluate the distances between clusters and it attempts to minimize the Sum of Squares (SS) of any two clusters that can be formed at each step. Observations in a specific cluster share many characteristics in common, but are very dissimilar to observations not belonging to that cluster (Ward, 1963). Among the different types of clustering hierarchical clustering is by far the most widely used clustering method. In cluster analysis performing Mahalanobis's (D 2 ) statistic analysis Mahalanobis (1936) is important which uses for assessing the genetic divergence among the test entries in different clusters. If there is a large jump in the distance between clusters from one stage to another then this suggests that at one stage clusters that are relatively close together were joined whereas, at the following stage, the clusters that were joined were relatively far apart. In any plant breeding program the final objective is to boost quality and/or quantity of a required crop. knowing the association between the required traits and other related traits is a prerequisite for such programs. Hence, correlation coefficient can measure such simple linear relationship between different traits. Correlation coefficients range between -1 and +1 and measure the degree and direction of relationships between various traits. Yield is a dependable complex inherited character as a result of interaction of several contributing factors that may be related or unrelated (Subramanian and Subramanian, 1994).