INTRODUCTION Niger (Guizotia abyssinica (L.) Cass.) belonging to family Compositae is an oilseed crop grown in Ethiopia and India, accounting for about 50% of Ethiopian and 3% of Indian oilseed production (Getinet and Sharma 1996). Five of six species, including niger of the genus Guizotia, are native to the Ethiopian highlands. The species of the genus are diploid with 2n=30 chromosomes (Hiremath and Murthy 1992; Dagne, 1994). Niger is an annual dicot with epigeal germination, and seedlings have pale green to tan hypocotyls and cotyledons (Seegeler, 1983). It is usually grown on light, poor, coarse-textured soils (Chavan, 1961). It is a fully outbred species with a self-incompatibility mechanism (Chavan, 1961; Mohanty, 1964; Shrivastava and Shomwanshi 1974; Sujatha, 1993) and is entomophilous, particularly via bees (Ramachandran and Menon 1979). The pale yellow niger seed oil has a nutty flavor and a pleasant odour (Getinet and Sharma 1996). The seed contains about 40% oil with a fatty acid composition of 75-80% linoleic acid, 7-8% palmitic and stearic acid, and 5-8% oleic acid (Getinet and Teklewold 1995). The Indian varieties contain 25% oleic acid and 55% linoleic acid (Nasirullah et al. 1982). The meal left after oil extraction is free of toxins but contains more crude fiber than most oilseed meals. Niger's oil, protein, and fiber content are affected by husk thickness, and thick-skinned seeds tend to contain less oil and protein and more fiber (Getinet and Sharma 1996). Characterization is the description of plant germplasm. Morphological characters are easily observable, and characterization helps identify suitable genotypes, assist breeders in selecting diverse parents for breeding, and adopt effective breeding methodologies, which may aid in the genetic improvement of crops (Shilpashree et al., 2021). Phylogenetic relationships between various lines could be revealed using morphological characterization to limit recurring parents and benefit breeders in developing enhanced varieties with a broader genetic base (Thakur et al., 2022). Considering the above point of view, the main objective of this experiment is to characterize the niger accessions based on their morphological traits. MATERIAL AND METHODS In the present research, a total of 103 accessions (Table 1), including three checks (JNS-9, JNS-30, and JNS-28), were evaluated which were collected from Project Coordinating Unit, All India Coordinated Research Project on Sesame and Niger (ICAR), JNKVV Campus, Jabalpur, M.P., India. Spacing between row to row and plant to plant was kept at 45.0 cm and 15.0 cm. The experiment was conducted using an un-replicated Augmented Block Design for two seasons during Kharif, 2020 and 2021. The observations were recorded on 22 traits viz. leaf serration, leaf shape, leaf color, leaf angle of branching, leaf length, leaf width, stem color, stem hairiness, pollen color, the color of ray floret, number of ray florets, the color of disc floret, number of bracts, number of nodes, internode length, plant branching habit, the diameter of capitula, lodging tendency, seed shape, seed length, seed color, and seed texture. Twenty-two morphological traits have been considered essential for describing hundred and three niger accessions. RESULT AND DISCUSSION A total of 22 morphological traits of the niger accessions were studied and results revealed that a significant amount of variation was recorded in almost all the traits studied. Grouping and the frequency distribution of accessions have been provided in Table 2 and its discussion in this section. Various taxa of dicotyledonous plants have leaves possessing regular and familiar patterns of architectural organization for example; the dicot plant can have its margin as entire, lobed, or toothed (serrate and dentate) (Hickey, 1973). The niger accessions were grouped as entire, serrate, and dentate based on leaf serration of margin. A maximum number of accessions were observed as serrate (94) followed by dentate (05) and entire (04). Gebeyehu et al. (2021) and Kumar et al. (2021) also observed same trait in their experiments on niger. The leaf is of prime importance to the rape, substitute as the plant's power generator and aerial environmental sensor (Bylesjo et al., 2008; Efroni et al., 2010). The number, area, shape, and size of leaves are important to plant science, allowing scientists to distinguish between different species and even to model climate change (Cope et al., 2012). In the case of leaf shape, maximum accessions were medium (58), followed by broad (28) and narrow (17). Kumar et al. (2021) reported similar findings. The intensity of the green color is a clear indication of Chlorophyll pigment in leaves. The leaf chlorophyll content is often well correlated with plant metabolic activity, e.g., photosynthetic capacity and RuBP carboxylase activity (Evans, 1983; Seeman et al., 1987), plant stress (Eagles et al., 1983; Fanizza et al., 1991), and leaf N concentration as well. In the study for the trait of leaf color, maximum green leaf color (76) was observed, followed by light green (19) and dark green (08). None of the accessions had very light green and dark green leaf colors. Gebeyehu et al. (2021), Kumar et al. (2021), and Rani et al. (2010) also used this trait as one of the criteria for characterization of genotypes in niger. Branch angle is a key morphological trait that shapes the canopy design and influences yield. Plants with effectively small branch angles exhibit compact canopy architectures, and these plants are, for that reason, more suitable for high-density planting (Wang et al., 2014), so a condensed canopy architecture maintains light capture under elevated densities by minimizing shade by adjacent plants (Sun et al., 2016). In the trait leaf angle of branching, maximum accessions were observed as having erect (acute) (52) followed by horizontal (39 accessions), erect (07 accessions), and 05 accessions were observed as having hanging branches. Kumar et al. (2021) reported similar findings. Based on length of leaf, accessions were categorized into three classes i.e. small, medium and long. Most accessions were observed as medium (81) followed by long (20) and small (02). In leaf width trait, a maximum number of accessions (77) were observed as having medium width followed by narrow (25) and broad (01). In the case of stem color, most accessions (79) were observed as purple colored, followed by purplish green (19), and 05 accessions had green stem color. Rani et al. (2010), Kumar et al. (2021), and Gebeyehu et al. (2021) observed same trait for categorizing niger genotypes. Hairiness and pubescence are reported to be a usual defense mechanism for biotic and abiotic factors, and they are rich in defense-related proteins also (Amme et al., 2005). In the study for the trait of stem hairiness, maximum accessions were observed as sparse (81), followed by medium (17) and dense (04). None of the accessions were found to be glabrous (0). Gebeyehu et al. (2021), Ranjithkumar and Bisen (2021) and Kumar et al. (2021) also elucidated this trait. Diverse flowers produce different carotenoids. The flowers become intensely dark as the amount of pigment elevates (Miller et al., 2011). In the case of pollen color, most of the accessions (87) were observed as a yellow color, and 16 accessions were pale yellow. In the study for the trait of the color of ray floret, was observed maximum yellow (88) followed by pale yellow (10) and whitish yellow (05) in niger accessions. Kumar et al. (2021) reported similar findings. In the inflorescence of the family Asteraceae, the capitulum comprises the ray florets (outer florets) and the disc florets (inner florets) and can be regarded as the basic pollination unit (Leppick1977). In the case of no. of ray florets, most of the accessions (79) had seven-eight ray florets, followed by more than eight ray florets (20) and up to six ray florets (04). Kumar et al. (2021) reported similar results. In the study for the trait of the color of disc floret, maximum accessions were observed as yellow (95), and eight accessions had purple-colored disc floret. In the case of the number of bracts, all the accessions under study (103) were observed as having five bracts. None of the accessions had more than five bracts (0). In the case of the number of nodes, most of the accessions (50) had ten to fourteen nodes followed by more than fourteen nodes (35) and up to ten nodes (18). In the study of internode length trait, the maximum number of accessions (66) were observed as having medium internode length followed by small (32) and long (05). Plant growth habit is a significant agronomic trait since a dense ground cover affects the interception of light for photosynthetic buildup, the inhibition of weed development, and the decline of water evaporation from soil (Baum et al., 2003). In the case of plant branching habit, most accessions were erect (89), and fourteen accessions were drooping. In the trait of diameter of capitula, the maximum number of accessions (71) were small, followed by medium (29) and large (03). Gebeyehu et al. (2021) and Rani et al. (2010) elucidated this trait for characterization of niger germplasm. Lodging tendency was present in maximum accessions (60), followed by absent in 43 accessions. Rani et al. (2010) also explained this trait during their studies on the characterization of niger genotypes. In the case of seed shape, most of the accessions were elongated ovate (94) followed by elongated (06) and ovate (03). Kumar et al. (2021) studied same trait and reported similar findings. In the case of seed length, maximum accessions were medium (99), followed by small (03) and large (01). All former researchers in sesame outlined seed coat color under digenic control with several puzzling segregants beyond possible explanation (Baydar and Turgut, 2000; Falusi, 2007). In recent times Zhang et al. (2013) using a high-density linkage map, analyzed the genetic segregation and quantitative trait loci (QTL) for sesame seed coat color and showed that two major genes with additive dominant- epistatic effects together with polygenes were answerable for controlling the seed coat color trait. In the trait of seed color, a maximum number of accessions (70) were brown, followed by dark brown (23) and black (10). Rani et al. (2010) and Kumar et al. (2021) also observed same trait in their experiments on niger. In the case of seed texture, most of the accessions were smooth (90), and 13 were rough. Genetic diversity analysis using morphological traits In the present investigation, the genetic divergence of 103 niger accessions including 03 checks viz., JNS-9, JNS-30 and JNS-28. was determined by using nominal variables of morphological characters, which were used as an input for Nbclust hierarchical cluster analysis in which clustering was done using Ward’s minimum variance method and Euclidean’s method of genetic distance was derived. The Phylogeny tree was further constructed based on clustering using the igraph package. The dendrogram and phylogeny tree were constructed by using R studio software ver. 4.1.2. Grouping of genotypes into different clusters In the present study, 103 niger accessions were grouped into 5 clusters based on analysis of divergence at the genetic distance of 10 (Table 3). The clustering of genotypes was grouped mainly by their morphological differences. Cluster V was the largest among all clusters comprising 61 genotypes. Cluster IV has 35 genotypes, Cluster II has five genotypes, and Cluster I and Cluster III have one genotype each i.e. monogenotypic. The maximum genetic distance was found between the genotypes of cluster II and Cluster IV, followed by Cluster IV and Cluster V. So, good recombinants can be obtained on mating between clusters II ((PCU-32, PC-30, PCU-47, BMD-202, and BMD-204) and Cluster IV (BMD-197, BMD-219, AJSR-1, JNS-9, PCU-43, JNS-9, BMD-196, JNS-28, BMD-190, and AJSR-5). In contrast, the minimum genetic distance was found between cluster I and Cluster II genotypes, followed by Cluster I and Cluster III. As a result, on mating lines between those clusters, good recombinants may not be obtained.