Impaginato 239 Adv. Hort. Sci., 2024 38(3): 239­248 DOI: 10.36253/ahsc­15528 https://oaj.fupress.net/index.php/ahs Assessment of genetic parameters and heritability of Dendrobium species section Spatulata native to Indonesia E.W. Tini 1, P. Widodo 2, Sugiyono 2, Z. Ulinnuha 1 (*) 1 Jenderal Soedirman University, Faculty of Agriculture, Department of Agrotechnology, Purwokerto, Indonesia. 2 Jenderal Soedirman University, Faculty of Biology, Department of Biology, Purwokerto, Indonesia. Key word: Diversity, morphological traits, Orchidaceae, plant breeding. Abstract: Being one of the most abundant genera of orchids, Dendrobium pre­ sents a valuable genetic resource for hybridization programs. Morphological characterization and assessment of genetic parameters plays a crucial role in establishing genetic connections among orchid species within the same genus. The study aims to discern the morphological traits of five Indonesian Dendrobium species, intending to evaluate their potential as candidates for crossbreeding programs. The materials used in this study were D. antennatum, D. discolor, D. stratiotes, D. lineale, D. gouldii, and D. sylvanum. This research examines 21 quantitative traits and 21 qualitative morphological traits of the studied Dendrobium. The findings reveal variations in characters related to flowers, leaves, and pseudobulbs. The analysis of genetic parameters indicates the presence of genetic diversity in traits such as flower stalk length, length of inflorescence, flower series length, flower length, flower width, dorsal sepal width, lateral sepal width, petal length, petal width, labellum length, labellum width, and the number of florets. All observed traits demonstrate high heri­ tability. So, the characters that have high genetic variability and heritability are valuable in selection criteria for plant breeding. 1. Introduction Indonesia possesses abundant biodiversity, encompassing a variety of orchids. Out of the approximately 30,000 orchid species worldwide, around 5,000 are present in Indonesia, distributed across diverse regions, with certain species being endemic to the country (Puspitaningtyas, 2020). Dendrobium as the most plentiful genus of orchids globally, boast­ ing approximately 1,600 species and holding the title of the largest genus within the Orchidaceae family. The collective number of hybrids, derived from both natural variations and crossbreeding, exceeds 20,000 and encompasses single and multi­genera varieties (Hartati et al., 2021). Indonesia also known for hosting a significant variety of Dendrobium (*) Corresponding author: zulfaulinnuha@unsoed.ac.id Citation: TINI E.W., WIDODO P., SUGIYONO, ULINNUHA Z., 2024 ­ Assessment of genetic parameters and heritability of Dendrobium species sec‐ tion Spatulata native to Indonesia. ­ Adv. Hort. Sci., 38(3): 239­248. ORCID: EWT: 0000­0001­5122­5507 PW: 0000­0002­2203­7168 S: 0000­0003­2002­9196 ZU: 0009­0003­8675­9252 Copyright: © 2024 Tini E.W., Widodo P., Sugiyono, Ulinnuha Z. This is an open access, peer reviewed article published by Firenze University Press (https://www.fupress.com) and distributed, except where otherwise noted, under the terms of CC BY 4.0 License for content and CC0 1.0 Universal for metadata. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Competing Interests: The authors declare no competing interests. Received for publication 15 December 2023 Accepted for publication 13 June 2024 AHS Advances in Horticultural Science AHS ­ Firenze University Press ISSN 1592­1573 (on line) ­ 0394­6169 (print) http://doi.org/10.36253/ahsc-15528 http://oaj.fupress.net/index.php/ahs http://orcid.org/0000-0001-5122-5507 http://orcid.org/0000-0002-2203-7168 http://orcid.org/0000-0003-2002-9196 http://orcid.org/0009-0003-8675-9252 http://www.fupress.com http://creativecommons.org/licenses/by/4.0/legalcode http://creativecommons.org/publicdomain/zero/1.0/legalcode Adv. Hort. Sci., 2024 38(3): 239­248 240 orchids, contributing to the overall diversity of orchid species in the region (Rahayu and Yusri, 2022). Schuiteman (2012) has identified 20 sections of Dendrobium, and one of these is the Spatulata sec­ tion. The Spatulata species within the section display significant diversity in flower characters, encompass­ ing variations in colors, labellum shapes and colors, horn shapes and colors, as well as the duration of flower bloom shelf life. Therefore, it is essential to assess the genetic variation of these species to offer fundamental genetic insights and facilitate genetic enhancements within the Spatulata orchid section (Purwantoro et al., 2023). To discern the variations among species, it is essential to employ a characteri­ zation method. Utilizing morphological features such as leaves, stems, tubers, fruits, and roots for charac­ terization is anticipated to facilitate the identification and understanding of the specific utility of these characterized plants (De et al., 2015). Observing mor­ phological characters is visually straightforward, allowing for a swift assessment of their diversity in comparison to other traits. Furthermore, employing morphological characterization proves valuable in evaluating the relationships among orchids, which is crucial for conservation initiatives and enhances the practicality of plant genetic resources (Vo et al., 2015). While the assessment of genetic relationships through morphological characters can be significantly affected by environmental factors, it remains essen­ tial to thoroughly characterize these traits. This thor­ ough characterization is necessary to ease the utiliza­ tion of germplasm by breeders (Aloysius et al., 2017). The characterization of plants plays a crucial role in evaluating the genetic proximity between orchid species within the same genus, influencing the effec­ tiveness of plant crossbreeding. A more intimate genetic connection enhances the likelihood of suc­ cessful crosses. This characterization serves not only to craft plant descriptions but also to ascertain the genetic relationships among different species (Mursyidin et al., 2021). In genetics studies of quanti­ tative traits, the primary role of heritability lies in its predictive function, indicating the dependability of phenotypic value as a predictor of breeding value (Ponzi et al., 2018). Genetic variability in plant breed­ ing refers to the range of genetic differences or varia­ tions that exist among individuals within a population of plants. It is a key concept in plant breeding because this variability is the raw material that plant breeders work with to develop new and improved crop varieties (Yani et al., 2018). By assessing genetic variability, plant breeders can identify traits that exhibit variation within a population. This informa­ tion is crucial for selecting traits that are desirable and heritable, meaning they can be passed on to future generations (Wirasti and Purwantoro, 2018). Traits with high heritability are more likely to respond positively to selection, making them prime candidates for improvement through breeding (George et al., 2020). The objective of this research is to characterize the Dendrobium section Spatulata orchid from Indonesia and investigate its genetic diversity and heritability as part of a plant breeding initiative. 2. Materials and Methods Experimental location The research was carried out in Banjarsari village, Sumbang District, Banyumas Regency, Central Java Province, Indonesia 7.3576° S, 109.2445° E. The research was carried out from March to June 2023. Experimental materials The characterization was conducted on the fol­ lowing Dendrobium orchids: D. antennatum, D. dis‐ color, D. stratiotes, D. lineale, D. gouldii, and D. syl‐ vanum. These plants were sourced from farmers and orchid collectors in Indonesia, and they represent mature specimens in the flowering stage. A total of three plants per species were analyzed. The tools used are digital calipers, rulers, digital single­lens reflex (DSLR) cameras, and writing instruments. Cultivation methods Dendrobium was cultivated in a screen house with 50% shade. Air temperature at daytime temperature around 27­32°C and nighttime temperature around 22­25°C, and humidity levels between 50­80%. Plants are watered once a day or according to plant needs. If the media humidity is still high, the plants can be watered every two days. The medium used for culti­ vation is charcoal. Fertilization is carried out once a week with NPK 20:20:20 fertilizer with follicular application. Regularly inspect Dendrobium orchids for pests. Additionally, monitor the orchids for signs of fungal or bacterial diseases and take necessary pre­ cautions to prevent spread. Characterization procedure The characterization procedure is based on the Tini et al. ‐ Genetic parameters of Indonesian Dendrobium section spatulata 241 Orchid Characterization Guidelines published by the Indonesian Ornamental Plant Research Institute which was adapted from the Dendrobium Characterization Guidelines by the International Union for the Protection of New Varieties of Plants (UPOV). Variables observed and analyzed were nature of stem, leaf shape, apexes of leaf, apexes of dorsal sepal, apex of lateral sepal, apex of petal, petal curva­ ture, lip shape, lip margin, dorsal sepal shape, lateral sepal shape, petal shape, dorsal sepal cross section, lateral sepal cross section, petal cross section, lip overlapping of basal part, lip shape of lateral lobe, lip shape of apical lobe, lip type of curving, lip shape of eye, color of anther cap; plant height (cm), pseudob­ ulb diameter (cm), internode length (cm), leaf length (cm), leaf width (cm), leaf area (cm2), peduncle­ovary length (cm), length of inflorescence (cm), length of flower arrangement (cm), leaf thickness (mm), flower length (cm), flower width (cm), dorsal sepal length (cm), dorsal sepal width (cm), lateral sepal length (cm), lateral sepal width (cm), petal length (cm), petal width (cm), labellum length (cm), labellum width (cm), number of flowers per spike. The tools used are digital calipers, rulers, digital single­lens reflex (DSLR) cameras, and writing instruments. Statistical analysis To evaluate the performance of observed traits, conducted a variance analysis. The estimation of genetic parameters such as Coefficient of Genetic Varibility (CGV), Coefficient of Phenotypic Variability (CPV) and Heritability followed Jambormias (2014) steps. 3. Results Dendrobium species origin Dendrobium antennatum is native to Papua (Indonesia) (Table 1, Fig. 1). These orchids thrive on tall tree branches within coastal forests, mangrove swamps, and rainforests, typically below 1200 meters in elevation. Dendrobium discolor var. Tanimbar is native to the Tanimbar Islands. It thrives in warm to hot cli­ mates, growing both as an epiphyte and a lithophyte. It can be found in various habitats, including man­ grove forests along the coast, behind sand dunes where it may experience salt spray, as well as on cliffs and rock faces up to an elevation of 550 meters. Dendrobium stratiotes is native to the Moluccas (including Halmahera and Morotai), the Sunda Islands, and Sulawesi, this orchid thrives at lower ele­ vations. It typically grows as a medium to large­sized epiphyte, preferring warm to hot conditions, often forming clustered groups. Dendrobium lineale is native to Papua, this orchid species grows as a large to giant­sized plant, thriving in warm to hot climates as either an epiphyte or Fig. 1 ­ Six species of Dendrobium section Spatulata native to Indonesia studied. Table 1 ­ Dendrobium species used in the study Name of germplasm Source of germplasm Dendrobium antenna‐ tum Papua Dendrobium discolor var. Tanimbar Tanimbar Island, Maluku Dendrobium stratiotes Western Papua, the Moluccas (Halmaheira and Morotai), the Sunda Islands and Sulawesi Dendrobium lineale Papua Dendrobium gouldii Papua Dendrobium sylvanum Papua, New Guinea Adv. Hort. Sci., 2024 38(3): 239­248 242 lithophyte. It is typically found at elevations of up to 800 meters, often near streams and coastal areas. Dendrobium gouldii is native to Papua. This orchid species grows as a large to giant­sized plant, thriving in warm to hot climates as either an epiphyte or lithophyte. It can be found in riverine forests, coastal forests, swamp forests, beaches, and plantations, typically at altitudes ranging from sea level to 700 meters. Dendrobium sylvanum is native to Papua New Guinea in lowland areas, this orchid species grows as a large to giant­sized epiphyte, thriving in warm cli­ mates. Morphological characters Most diversity was found in the characters of leaves (leaf shape, apexes of leaf), pseudobulb (nature of stem), flowers (apexes of dorsal sepal, apex of lateral sepal, apex of petal, petal curvature, lip shape, lip margin, dorsal sepal cross­section, later­ al sepal cross­section, petal cross­section, lip overlap­ ping of basal part, lip shape of lateral lobe, lip shape of apical lobe, lip type of curving, and lip shape of eye) (Table 2). Table 2 ­ Qualitative characters of Dendrobium studied Flowers In this study, all the flower parts of Dendrobium that were observed had diverse characters, even though they were still in one section, namely the Spatulata section. The section Spatulata includes several species known for their characteristic flat­ tened or spatula­shaped lip petals. This diversity shows differences in the shape of the petals, dorsal sepals, lateral sepals and labellum. The Spatulata section’s characters are the dorsal, lateral sepal and petal shapes were categorized as narrow elliptic. However, there is diversity in petal curvature, namely, D. antennatum and D. statiotes exhibit a spiral pattern. Conversely, in D. discolor, D. gouldii, and D. sylvanum, the curvature is deflexed, while in D. lineale, it remains straight. The diversity in the labellum lies in the lip shape of the lateral lobe, namely in D. antennatum, D. sylvanum, and D. lineale it is triangular, while in D. discolor it is broadly trapezoidal, and in D. gouldii and D. stratiotes it is ovate. Variability is also found in the lip shape of the apical lobe, namely in D. antennatum, D. stratiotes, D. discolor, D. gouldii it is rhombic, while in D. lineale it is reniform, and in D. No. Characters D. antennatum D. discolor D. stratiotes D. lineale D. gouldii D. sylvanum 1 Nature of stem Cane cylindric Cane cylindric Cane Cane cylindric Cane cylindric Cane cylindric 2 Leaf shape Lenceolate Lanceolate Lanceolate Elliptic Ovate Lanceolate 3 Apexes of leaf Acute Obtuse Acute Acute Acute Obtuse 4 Apexes of dorsal sepal Acuminate Obtuse Acuminate Acute Obtuse Obtuse 5 Apex of lateral sepal Acuminate Obtuse Acuminate Acute Obtuse Obtuse 6 Apex of petal Acuminate Obtuse Acuminate Acute Obtuse Obtuse 7 Petal curvature Spiral Deflexed Spiral Straight Deflexed Deflexed 8 Lip shape Ovate Undulate Ovate Ovate Oblong Obovate 9 Lip margin Entire Undulate Entire Undulate Undulate Undulate 10 Dorsal sepal shape Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic 11 Lateral sepal shape Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic 12 Petal shape Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic Narrow elliptic 13 Dorsal sepal cross section Narrow elliptic Moderately convex Strongly concave Strongly concave Strongly concave Moderately convex 14 Lateral sepal cross section Narrow elliptic Moderately convex Strongly concave Strongly concave Strongly concave Flat 15 Petal cross section Narrow elliptic Straight Strongly concave Strongly concave Strongly concave Moderately concave 16 Lip overlapping of basal part Present Absent Present Present Absent Absent 17 Lip shape of lateral lobe Tringular Broad trapezoid Ovate Tringular Ovate Triangular 18 Lip shape of apical lobe Rhombic Rhombic Rhombic Reniform Rhombic Elliptic 19 Lip type of curving Type I Type 1 Type 1 Type I Type VI Type IV 20 Lip shape of eye Type I Type 1 Type 1 Type I Type II Type I 21 Color of anther cap Yellow Yellow Yellow Yellow Yellow Yellow Tini et al. ‐ Genetic parameters of Indonesian Dendrobium section spatulata 243 sylvanumit is elliptic (Table 2). There was diversity in the quantitative flower parameters observed (Table 3). The length of the flowers in D. sylvanum is smaller compared to other species, measuring only 2.36 cm, but the width of the flowers reaches 5.00 cm. This indicates that the petals and sepals extend outward. This flower type is also similar to D. gouldii, characterized by a length of 3.43 cm and a width of 5.26 cm. D. antennatum and D. stratiotes have petal shapes resembling antlers, resulting in a longer length than width. Besides that, in D. antennatum, the length is 4.75 cm, and the width is 2.15 cm. For D. discolor and D. lineale, the proportions of flower length and width are more or less the same. The flower size of Dendrobium studied showed that D. stratiotes had the largest flower length, namely 9.33 cm compared to other species. This is related to the longer petals on D stratiotes, namely 6.23 cm. Besides that, in D. discolor, the length is 4.50 cm, and the width is 4.00 cm. In D. lineale, the length is 5.15 cm, and the width is 6.16 cm. Leaves Leaves characterization included leaf shape, apex­ es of leaf, leaf length (cm), leaf width (cm), and leaf area (cm2). The variability in the leaf shape of Dendrobium was D. antennatum, D. discolor, D. stra‐ tiotes, and D. sylvanum, being lanceolate. In contrast, D. lineale has an elliptic shape, and D. gouldii has an ovate shape. Variability in the apexes of leaves in D. antennatum, D. stratiotes, D. linelae, D. gouldii is acute, D. sylvanum and D. discolor are obtuse. Variability in leaf length is not wide, namely around 10.93 ­ 13.67 cm. The narrowest leaf width is D. antennatum, which is 2.50 cm, while the widest is D. discolor, which is 4.13 cm. The difference in leaf width affects the leaf area, the largest leaf on D. dis‐ color is 47.30 cm2, while the smallest leaf is D. anten‐ natum, namely 25.13 cm2. Pseudo bulb There is variation in the height among the observed Dendrobium species. Specifically, in D. stra‐ tiotes and D. gouldii, the height exceeds 100 cm, reaching 108.50 cm and 156 cm, respectively. In con­ trast, D. lineale reaches a height of 90 cm, while D. antennatum and D. discolor have heights of 51.33 cm and 57.33 cm. The lowest height is recorded in D. syl‐ vanum at 34.60 cm. Additionally, the length of pseu­ do bulb internodes varies across different Table 3 ­ Quantitative characters of Dendrobium species studied No. Characters D. antennatum D. discolor D. stratiotes D. lineale D. gouldii D. sylvanum 1 Plant height (cm) 51.33 57.33 108.5 90.00 156.00 34.6 2 Pseudobulb diameter (cm) 38.3 43.00 45.00 25.2 21.67 22.5 3 Internode length (cm) 8.1 12.80 11.6 4.13 5.13 4.4 4 Leaf length (cm) 12.2 13.6 13.26 10.93 13.67 12.00 5 Leaf width (cm) 2.5 4.13 2.96 3.83 2.83 3.5 6 Leaf area (cm2) 25.13 47.3 34.2 36.00 35.96 33.6 7 Peduncle­ovary length (cm) 2.66 2.2 3.4 2.06 2.4 1.6 8 Length of inflorescence (cm) 12.00 32.00 20.00 58.00 50.00 20.00 9 Length of flower arrangement (cm) 5.00 26.00 14.5 48.00 41.00 14.00 10 Leaf thickness (mm) 2.3 1.03 1.7 1.43 1.9 1.2 11 Flower length (cm) 4.75 4.5 9.33 5.15 3.43 2.36 12 Flower width (cm) 2.15 4.00 2.7 6.16 5.26 5.00 13 Dorsal sepal length (cm) 2.00 2.5 1.98 2.1 1.6 1.56 14 Dorsal sepal width (cm) 0.4 0.7 1.00 1.3 0.83 0.6 15 Lateral sepal length (cm) 1.85 2.5 2.6 2.9 1.9 2.36 16 Lateral sepal width (cm) 0.65 0.6 0.93 1.16 0.56 0.63 17 Petal length (cm) 3.8 4.3 6.23 4.4 3.00 2.93 18 Petal width (cm) 0.15 0.7 0.35 0.8 1.06 0.8 19 Labellum length (cm) 1.65 2.5 3.7 2.7 2.23 2.26 20 Labellum width (cm) 1.05 1.00 0.96 1.5 0.7 0.63 21 Number of flowers per spike 6.00 13.00 8.3 25.00 19.67 12.00 244 Adv. Hort. Sci., 2024 38(3): 239­248 Dendrobium species. The lengths of D. discolor and D. stratiotes measure 12.80 cm and 11.60 cm, respec­ tively. D. antennatum exhibits a length of 8.10 cm, while the shortest internodes are observed in D. lin‐ eale, D. gouldii, and D. sylvanum at 4.13 cm, 5.13 cm, and 4.40 cm, respectively. This suggests that plant height does not necessarily corellate to longer pseudobulb internodes in Dendrobium species. Besides that, the diameter of the pseudobulb varies among different Dendrobium species. In D. antenna‐ tum, D. discolor, and D. stratiotes, the pseudobulb diameter reaches 38.30 cm, 43.00 cm, and 45.00 cm, respectively. Meanwhile, for D. lineale, D. gouldii, and D. sylvanum, it is around 25.20 cm, 21.67 cm, and 22.50 cm. Genetic parameters The analysis of variance revealed a significant effect of Dendrobium species on all observed traits. A low coefficient of variation indicates that the variation in the data from the average is relatively small compared to the average value (Table 3). This early finding suggested the presence of genetic diversity within the Dendrobium species. The variance attributed to genotypes was highly significant for all the studied characteristics, indicating that the selected genotypes were genetically different (Table 4). Genetic parameter estimation was conducted to verify the presence of genetic variability within the Dendrobium section Spatulata were observed. The high values of broad­sense heritability (Hbs) and genotypic coefficient of variation (GCV) suggest a substantial genetic influence on phenotypic variability. The genetic variability coefficient (Table 5) showed that the flowering characters, namely flower stalk length (24.86), length of inflorescence (56.43), flower series length (74.40), flower length (47.91), flower width (36.08), dorsal sepal width (38.99), lateral sepal width (31.29), petal length (29.39), petal width (51.72), labellum length (27.12), labellum width (31.38), number of florets (50.10) are included in the high genetic variability category. Other vegetative characters are leaf width (45.43), leaf thickness (28.24), leaf area (51.77), plant height (57.66), stem diameter (42.72) also characterized by high genetic variability. Besides that, the length of dorsal sepal (17.63) and lateral sepal (17.07) was categorized as moderate genetic variability, whereas the length of leaf (8.43) was categorized as low genetic variability. Table 4 ­ Analysis of variance (mean square) for quantitative characters in Dendrobium species studied Characters Mean square CV (%) Replication Genotype Error Peduncle­ovary length (cm) 0.035555556 1.116888889 0.058222222 10.10063 Length of inflorescence (cm) 1.791666667 989.3 0.691666667 2.585478 Length of flower arrangement (cm) 0.1666666667 885.125 0.166666667 1.768585 Leaf length (cm) 0.157222222 3.527555556 0.136555556 2.930227 Leaf width (cm) 0.093888889 16.32588889 0.041888889 3.991354 Leaf thickness (mm) 0.002222222 0.659222222 0.050888889 14.14823 Leaf area (cm2) 21.86166667 2476.621333 11.763 6.194563 Plant height (cm) 141.5555556 6649.747222 57.32222222 9.313237 Pseudobulb diameter (mm) 15.73388889 130.8982222 2.509888889 10.34715 Internode length (cm) 0.035 0.569 0.055 5.350284 Flower length (cm) 0.223888889 17.07922222 0.392222222 12.72345 Flower width (cm) 0.292638889 7.282138889 0.345305556 13.94501 Dorsal sepal length (cm) 0.000688889 0.358688889 0.000555556 1.203245 Dorsal sepal width (cm) 0.010555556 0.300555556 0.004555556 8.378672 Lateral sepal length (cm) 0.005138889 0.504138889 0.020138889 6.03166 Lateral sepal width (cm) 0.00125 0.171916667 0.002916667 7.121693 Petal length (cm) 0.010555556 4.404888889 0.025222222 3.863069 Petal width (cm) 0.001116667 0.335383333 0.00145 5.9037 Labellum length (cm) 0.000416667 1.396583333 0.00775 3.509664 Labellum width (cm) 0.000416667 0.28458333 0.00375 6.280743 Number of flowers per spike 8.166666667 152.5333333 4.9 15.81139 Tini et al. ‐ Genetic parameters of Indonesian Dendrobium section spatulata 245 All traits observed in this study had high heritability (Table 6). If genetic factors rather than environmental influences primarily determine a trait, it is more likely to have high heritability. Traits controlled by a few genes with large effects, known as major genes, are often highly heritable. Table 6 ­ Heritability of in the Dendrobium species studied Table 5 ­ Coefficient of genetic variability (CGV), and coefficient of phenotypic variability in the Dendrobium species studied Characters Range Mean CGV Category CPV Category Peduncle­ovary length (cm) 1.60 ­ 3.40 2.38 24.86 High 26.84 High Length of inflorescence (cm) 12.50 ­ 59.00 32.17 56.43 High 56.49 High Length of flower arrangement (cm) 5.00 ­ 48.00 23.08 74.4 High 74.42 High Leaf length (cm) 10.80 ­ 14.00 12.61 8.43 Low 8.92 Low Leaf width (cm) 2.40 ­ 9.00 5.12 45.43 High 45.6 High Leaf thickness (cm) 0.80 ­ 2.40 1.58 28.24 High 31.58 High Leaf area (cm2) 23.70 ­ 112.40 55.37 51.77 High 52.14 High Plant height (cm) 24.60 ­ 156.00 81.29 57.66 High 58.41 High Pseudobulb diameter (cm) 7.30 ­ 28.60 15.31 42.72 High 43.96 High Internode length (cm) 3.50 ­ 5.40 4.38 9.44 Low 10.85 Moderate Flower length (cm) 2.30 ­ 10.00 4.92 47.91 High 49.57 High Flower width (cm) 2.00 ­ 7.50 4.21 36.08 High 38.68 High Dorsal sepal length (cm) 1.60 ­ 2.50 1.95 17.63 Moderate 17.67 Moderate Dorsal sepal width (cm) 0.30 ­ 1.30 0.8 38.99 High 39.88 High Lateral sepal length (cm) 1.60 ­ 3.00 2.35 17.07 Moderate 18.1 Moderate Lateral sepal width (cm) 0.50 ­ 1.20 0.75 31.29 High 32.09 High Petal length (cm) 2.80 ­ 6.30 4.11 29.39 High 29.64 High Petal width (cm) 0.10 ­ 1.10 0.64 51.72 High 52.06 High Labellum length (cm) 1.50 ­ 3.80 2.5 27.12 High 27.35 High Labellum width (cm) 0.60 ­ 1.60 0.97 31.38 High 32 High Number of flowers per spike 6.00 ­ 25.00 14.00 50.1 High 52.54 High Characters σ2e σ2g σ2f H2bs Category Peduncle­ovary length (cm) 0.0582 0.3528 0.4111 85.83 High Length of inflorescence (cm) 0.6916 329.53 330.22 99.79 High Length of flower arrangement (cm) 0.1667 294.98 295.15 99.94 High Leaf length (cm) 0.1365 11.303 12.668 89.22 High Leaf width (cm) 0.0418 5.428 54.698 99.23 High Leaf thickness (cm) 0.05 0.202 0.253 79.93 High Leaf area (cm2) 11.763 821.61 833.38 98.58 High Plant height (cm) 57.32 2197.475 2254.797 97.45 High Pseudobulb diameter (cm) 2.509 42.796 45.306 94.46 High Internode length (cm) 0.055 0.1713 0.2263 75.69 High Flower length (cm) 0.392 5.562 5.954 93.41 High Flower width (cm) 0.3453 23.122 26.575 87 High Dorsal sepal length (cm) 0.0005 0.1193 0.1199 99.53 High Dorsal sepal width (cm) 0.0045 0.0986 0.1032 95.58 High Lateral sepal length (cm) 0.02 0.161 0.181 88.9 High Lateral sepal width (cm) 0.0029 0.056 0.059 95.07 High Petal length (cm) 0.0252 14.598 14.851 98.3 High Petal width (cm) 0.00145 0.11311 0.11276 98.71 High Labellum length (cm) 0.00775 0.4629 0.4706 98.35 High Labellum width (cm) 0.00375 0.0936 0.0973 96.14 High Number of flowers per spike 4.9 49.21 54.11 90.94 High Adv. Hort. Sci., 2024 38(3): 239­248 246 4. Discussion and Conclusions Morphological characteristics In the context of orchids, flowers typically consist of three outer floral parts known as sepals and three inner floral parts called petals. The petals are often more colorful and visually striking than the sepals. They play a crucial role in attracting pollinators, such as insects, and contribute to the overall aesthetic appeal of the orchid flower. The arrangement and characteristics of petals are important features used in the identification and classification of orchid species (Dirks­Mulder et al., 2017) In addition to attracting pollinators, orchid petals, along with other floral parts, may also have specialized structures or markings that aid in the orchid’s reproductive process, such as facilitating the transfer of pollen. Orchids are known for their intricate and diverse floral structures, and the characteristics of their petals contribute significantly to their overall beauty and ecological function (Li et al., 2021). The labellum is a specialized petal in orchids that stands out from the other floral parts due to its distinct shape, size, and often elaborate structure. It is the modified third petal of the orchid flower, differentiating from the two lateral petals and three sepals (Dalayap et al., 2011). The diversity in the part of Dendrobium flower studied, can be a source of diversity in plant breedingaimed at increasing the aesthetic value of hybrid Dendrobium orchids. Studying leaf shape contributes to understanding the phenotypic variation within a species. This information is essential for describing the diversity and range of characteristics exhibited by plants. Considerable genetic diversity exists in both the size and shape of leaves among different species and populations within the same species. This diversity was influenced by robust heredity, carrying both genetic and environmental information that contributes to variations (Ren et al., 2020). Pseudo bulb is a modified form of stem in several types of orchid plants. A pseudobulb in orchids is a specialized, swollen, or bulbous structure that serves as a storage organ for water and nutrients. This structure is a key adaptation to various environmental conditions, particularly in epiphytic and lithophytic orchids (Zhang et al., 2018). The pseudobulbs on Dendrobium orchids belong to the homoblastic type, characterized by two or more internodes of the same or varying lengths (Ng and Hew, 2000). Furthermore, the nature of stem (pseudobulbs) can vary significantly among different Dendrobium species. D. antennatum, D. discolor, D. lineale, D. gouldii, and D. sylvanum typically exhibit cylindrical canes. In contrast, D. stratiotes stands out with its cane­shaped stem, representing a distinctive morphological trait within the genus. The size of the pseudobulb indicates the large carbohydrate reserves in the organ. According to Ng and Hew (2000), carbohydrate reserves in orchid pseudobulbs are an important part in the initiation of new seedling growth. The large size of the pseudobulb also functions to support the growth of new shoot and flower development. Genetic parameters Genetic diversity plays an important role in the development of Dendrobium breedings with high economic value. It serves as the main germplasm in plant breeding. Greater genetic diversity increases the potential for enhancing plants in accordance with the desired traits. This variability offers ample opportunities for plant breeders to choose superior genotypes for improving crops (Swarup et al., 2021). High genetic diversity in plants reflects substantial genetic variation, signifying numerous genetic differences between individual plants. This diversity holds promising potential for more effective plant breeding endeavors. Moniruzzaman et al. (2012) supports this, emphasizing the critical role of high genetic diversity in breeding programs, particularly in the development of new crop varieties featuring improved traits like exotic flower diversity. Genetic variation offers breeders a wide genetic reservoir, enabling the selection and crossbreeding of individuals to produce desirable hybrids. In this study, high CGV values indicate that genetic factors have a significant influence on the observed traits. On the other hand, it is also known that there is a difference in value between CPV and CGV for each lower trait. These findings suggest that the environment has comparatively minor influence on the observed traits. This is in accordance with research of Malek et al. (2014) stated that narrow distinction between CPV and CGV in the majority of traits suggests a minimum impact of environmental factors on the manifestation of these traits, increasing the probability of achieving significant selection gains. The observation results showed that all the observed characters showed high broad sense Tini et al. ‐ Genetic parameters of Indonesian Dendrobium section spatulata 247 heritability (Table 6). This suggests that the variability in these traits is primarily influenced by genetic factors rather than environmental factors (Swarup et al., 2021). In the research of Singh et al. (2018) on Dendrobium orchid, heritability estimates were identified for characteristics such as plant height, leaf count per shoot, quantity of aerial roots, length and thickness of aerial roots, shoot thickness, internodal length, leaf length, and leaf area. Heritability values represent the degree of genetic impact on a trait (Hadi et al., 2019). Heritability of quantitative traits are influenced by multiple genes as well as environmental factors. If a trait is primarily determined by genetic factors rather than environmental influences, it is more likely to have high heritability. Traits controlled by a few genes with large effects, known as major genes, are often highly heritable. The potential for improvement through direct selection was indicated by high heritability with high genetic variability flower stalk length, length of inflorescence, flower arrangement length, flower length, flower width, dorsal sepal width, lateral sepal width, petal length, petal width, labellum length, labellum width, number of florets. When heritability is high in plants, it indicates that a significant genetic variation is a primary factor in the observed traits. High heritability typically indicates that the majority of phenotypic variation in a trait can be attributed to genetic factors, and this is frequently associated with the influence of additive genes (Amien et al., 2021). Additive genes contribute cumulatively to the phenotypic expression of a trait, and when these genes are predominant, heritability tends to be high (Beavis et al., 2021). Therefore, high heritability is commonly regarded as an indication that genetic factors, especially additive genes, exert a substantial influence on the plant’s traits (Karavolias et al., 2020). High GCV and Hbs values increase the chances of obtaining Dendrobium orchids have superior characters that can be inherited in their phylogeny. Genetic variability plays a crucial role in selecting parents for hybridization and breeding initiatives effectively (Mazid et al., 2013; Mai et al., 2021). 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