Maize seeds harbormany ectophytic and endophytic microbiomes including fungi, bacteria and actinomycetes. Several ectophytic mycoflora isolated were Aspergillus, Fusarium verticillioides, F. proliferatum, F. glutinans, Gibberella zeae, Penicillium, Macrophomina phaseolina, Diplodia, Nigrospora, Botryosphaeria, Cladosporium, Trichoderma, Rhizoctonia, and Rhizopus (Bhatnagar et al., 1999). Mycoflora infection in maize seeds causesa reduction in germination various abnormalities and leads to rejection (Singh et al., 2021). Storage fungus infects the seeds as they are moved into storage and, in the right circumstances, can quickly spread throughout the bulk. These fungi develop on maize seeds; they become visible, can kill the seed, generate an unpleasant odor or taste, and occasionally the seeds are unfit for human eating because the seed fungi release mycotoxin along with a change in the chemical makeup of the seed (Ingle et al., 2021). Mycoflora associated with maize seed are members of Aspergillus spp., Fusarium spp., and Penicillium spp., and these are mycotoxin producing fungi. Aspergillus spp., produces various mycotoxins and aflatoxin B1 is extremelytoxic andis classified as a group Ia human carcinogenic by the International Agency for Research on Cancer, in addition to considerable economic losses in the food and agricultural sectors. A study on fungal species diversity is one of the most important indices used to evaluate an ecosystem. Several diversity indices such as population dynamics, species richness, evenness, dominance of mycoflora, etc. are used. Usually, fungal species diversity is one of the most important indices used for the evaluation of an ecosystem. Fungal species richness, an intuitive element of fungal diversity, is commonly used to compare habitats, as species diversity is usually assumed to reflect niche diversity when limiting similarity drives species coexistence (Silvertown, 2004). Fungal diversity can change because of time, climate, biota, topography, natural disturbance, or human-caused perturbation and contamination (Day et al., 2019). For these reasons, there’s an interest in developing approaches to predict various facets of fungal diversity and how it is likely to change over space and time in natural and managed ecosystems. Alpha diversity reveals the biodiversity component of the community and whereas beta diversity reveals how it changes across locations. Understanding the compositional pattern of species helps researchers to understand different aspects of species interaction and ecosystem function (Legendre, 2014). Beta diversity patterns provide knowledge about the uniqueness of community composition in the landscape. Keeping this in view, the present investigation was designed to study the diversity of mycoflora of maize seeds collected from different maize growing areas of Tamil Nadu. MATERIALS AND METHODS Collection of seed samples. Maize seed samples were collected in ten locations covering major maize growing areas of Tamil Nadu that include Virudhunagar, Namakkal, Tiruppur, Madurai, Dharmapuri, Salem, Oddanchathiram, Ariyalur, Perambalur and Dindigul. One kg of seed samples were collected directly from maize growing farmers and seed sellers. In each location, seeds were collected in five different areas and the seeds were homogenized to represent one location. These homogenized seeds were subjected to mycoflora assessment in the Department of Plant Pathology, Tamil Nadu Agricultural University (TNAU), Coimbatore, Tamil Nadu. Mycoflora assessment. Mycoflora on maize seeds was assessed by the standard blotter method (De Tempe, 1963). One Hundred seeds from each location placed inplastic Petri dishes (90 mm dia.) lined with two layers of blotter papers and one layer of filter paper moistened with distilled water. Ten seeds will be placed in each Petri dish equidistantly (pattern 9-1). The seeded Petri dishes were incubated at 25 ± 1°C for seven days and the seeds were examined regularly for the presence of different fungi. Incubated seeds were examined visually under a Stereo-zoom microscope for the growth pattern of mycoflora (Kumar et al., 2017). Morphological identification of fungal genera. Individual fungal colonies which were observed under a stereo-zoom microscope were subcultured in potato dextrose agar medium. The fungal colonies were further purified by the single hyphal tip method. These pure cultures were then subjected to microscopic observation for morphological identification of the fungal species. Fungal genera were confirmed by both cultural and morphological characters. Computation of Diversity Indices Based on the individuals, fungi recorded in the distinct seed samples were analyzed for species richness and species distribution, evenness, alpha-diversity and beta-diversity. Shannon-Weiner index (H’) and Simpson’s index were widely used to describe the α-diversity. Computation of Relative Density The Relative Density (RD) of fungal species and genera was calculated according to the method suggested by Tadych et al. (2012). "Relative Density (RD) (%)" = ni/Ni x 100 Where, ni is the number of genus or species isolated, Ni is the total number of isolates. Computation of α-diversity. Alpha diversity can be found by calculating three parameters like Shannon –Wiener Diversity Index, Species Evenness Index and Simpson Diversity Index (D). The formulas for computing the above three parameters are as follows: Simpson Diversity Index (D). The Simpson Diversity Index represents the species diversity in a particular location "Simpson Diversity Index (D)" = (∑ n (n-1) )/(N(N-1)) Where, n is the total number of individuals in a particular species N is the total number of individuals "Shannon –Wiener Diversity Index (H’)" = ∑_(i=1)^s▒〖p_i ln⁡〖p_i 〗 〗 Where, Pi (relative abundance) is equal to ni/N ni is the number of individuals in ith species N is the total number of individuals (Shannon and Weaver, 1963) "Species Evenness Index"= (H’)/ln⁡(R) Where, H’ is the Shannon Wiener Index – ranging from 0 to 6. R is the species richness which is also equivalent to s (the number of species found in the given area). The next step is to proceed with ranking the values obtained for each index. In this paper, Fernando’s Biodiversity Scale was used to rank the indices (Table 1). Computation of β – Diversity. Beta diversity refers to the species diversity between any two regions. It is used for large-scale comparison of species diversity. β-diversity was calculated by using the following formula given by Fontana et al. (2020). "β-diversity = (" "N" _"1" "-C )\+(" "N" _"2" "-C)" Where, N1 refers to the total number of species present in location 1 N2 refers to the total number of species present in location 2 C refers to the number of species that both locations have in common Statistical analysis. Various diversity indices (α-Diversity, β-Diversity) were calculated, and graphs were drawn using ‘PAST’ software. RESULTS AND DISCUSSION Mycoflora assessment. Maize seeds collected from different maize growing areas of Tamil Nadu were used to assess the fungal diversity. A total of 803 fungal isolates belonging to ten different species were observed, out of which five belong to the genus Aspergillus, contributing 86.3 percent of the total fungal population. The fungal population was dominated by Aspergillus spp., followed by Fusarium spp., (6.23%). Other fungal genera recorded in the present study were Penicillium spp., (4.23%), Rhizopus spp., (2.37%), Alternaria spp., (0.37%) and Macrophomina (0.50%) (Data not shown; Fig. 1). The fungal genera were identified based on the following various cultural and morphological characters. Aspergillus flavus. The fungus produced olive or dark green colonies with profuse sporulation. Mycelium is hyaline, septate and branched. It produced circular single-celled green colored conidia arranged in chains from the biseriate phialide arising from the conidiophore (Fig. 2a). Aspergillus niger. The fungus had dark brown to black colonies with enormous sporulation. Mycelium is hyaline, septate and branched. Conidiophores were smooth, aseptate and unbranched. Biseriate conidial heads produced smooth black colored conidia in chains (Fig. 2b). Aspergillus fumigates. Initially, A. fumigatus produced white colonies, which later turned into dark bluish green colonies. They produced columnar conidial heads and uniseriate conidiophores. Conidia were globose, bluish green colored and were produced in basipetal succession (Fig. 2c). Aspergillus tamarii. Aspergillus tamarii produced olive green to brown colored colonies. Mycelium is hyaline, septate and branched. Conidiophores were colorless and biseriate in nature. Conidia were spherical and smooth surfaced in nature (Fig. 2d). Penicillium. Colonies were initially white and became bluish green upon full growth. The margins of the colonies were wavy and concentric rings were visible. On the reverse side of the plate, the colonies were red or pink-tinged at the center and the margin. Conidiophores were either branched or unbranched with metulae at the end. Metulae produced sterigmata in which the conidia were arranged. Conidium was small, uninucleate, globose or ovoid (Fig. 2e). Fusarium. Fusarium produced white fluffy colonies with violet to purple colored mycelium and brown zonation. Sickle-shaped septate macroconidia were observed. Both terminal and intercalary chlamydospores were observed. Chlamydospores were thick and smooth-walled. Rhizopus. Rhizopus produced dark greyish brown fluffy colonies. Simple globose sporangia were observed at the end of sporangiophores. Each sporangiophore arises from the root like a rhizoid. Sporangiospores were dark single-celled and globose to ovoid. Macrophomina. Colonies were dull white initially and turned to dark brown colored colonies upon time. Mycelium is septateand hyaline at initial stages but turns light brown upon growth. Dark brown colored, oval to spherical microsclerotia were produced by hardening of the fungal mycelium. Alternaria. Alternaria produced dull white to olive-colored colonies with white margins. Conidiophores were simple, septate, smooth walled and pale brown. Conidia were short, obclavate or ovoid with both transverse and longitudinal septa. This finding is in line with the work of Tsedaley and Adugna (2016), who recovered 110 fungal isolates from three maize varieties and the major fungi observed were Aspergillus, Fusarium and Penicillium. Aspergillus, Fusarium, Penicillium, Bipolaris maydis, Alternaria, Cephalosporium, Macrophomina, Diplodia, Nigrospora, Botryosphaeria, Cladosporium, Trichoderma, Rhizoctonia and Mucor have been reported from maize seed (Kumar et al., 2017). El-Shanshoury et al. (2004) isolated and identified eight fungal genera that belonged to Aspergillus, Penicillium, Fusarium, Mucor, Cladosporium, Trichoderma, Rhizopus and Alternaria using the standard blotter paper method. Mairevi et al. (2012) isolated Penicillium, Aspergillus, Alternaria and Fusarium from maize seed. Getachew et al. (2018) isolated Penicillium, Aspergillus and Fusarium from maize seeds collected from South and Southwestern Ethiopia. Relative Density (RD). In terms of Relative Density (RD), A. niger was dominant an RD% of 30, followed by A. flavus (27%) and A. fumigatus (20%) (Fig. 3). Aspergillus niger, A. flavus, A. tamarii and A. fumigates were observed in all locations (Fig. 4). A. oryzae was observed only in 4 locations. Fusarium spp., was observed in all the locations except in Virudhunagar region. Penicillium spp., was observed in 5 locations, Rhizopus spp., and Macrophomina each in 3 locations, and Alternaria spp., was observed in 2 locations. A higher number of mycoflora (118) was observed in Tirupur, followed by Dharmapuri (110). In other locations, it ranged from 44-102. α-Diversity. Shannon-Weiner (H’) explains the influence of abundance. As per Edwino Fernando’s Ranking of Biodiversity Indices, the Shannon index was less than 1.9 in all locations. In all locations, diversity was very low, hence mycoflora abundance was absent (Table 1). The highest Simpson’s index of 0.8019 was observed in the Ariyalur region, representing the highest dominance of mycoflora. The evenness index values were more than 0.5 in all the locations, which infers that species distribution is even (Table 2). Richness represents the number of species at a region or location. The highest species richness of about 8 was observed in Ariyalur;7 in Madurai and Dindigul; and 6 in Virudhunagar, Namakkal, Tiruppur, Dharmapuri, Oddanchathiram and Perambalur (Fig. 5). β-Diversity. Beta-diversity is diversity between sites (paired comparison) and it essentially quantifies the number of different communities in the region. Thus, it is the region's absolute number of distinct components (Tuomisto, 2010). Virudhunagar was 50% related to Oddanchathiram and Perambalur. Pairwise comparison between locations gave high dissimilarity since the values were less than 0.5. Low values suggest that there was no spatial variability in the distribution of mycoflora (Table 3). Genevieve et al. (2019) studied the difference in fungal composition between forest stands analyzed with permutational multivariate analysis of variance and beta-diversity partitioning analyses. The most prevalent fungi belonged to the orders Agaricales, Helotiales, and Russulales, while sites from Abitibi-North Témiscamingue's showed the highest OTU (Operational Taxonomic Unit) richness. Kumar et al. (2017) reported that the Simpson index of dominance (D), Shannon-Weaver index of diversity (H) and Evenness (E) of Aspergillus flavus contributed to fungal diversity. The dominance of mycoflora species varied from place to place and was influenced by various environmental factors, variety, cultivation method and soil, etc.