Morphological Characterization of Coorg Mandarin (Citrus reticulata Blanco) Based on DUS (Distinctness, Uniformity and Stability) Descriptors

Abstract

Aims: To assess the genetic diversity and phenotypic variation among seventy-three Coorg mandarin accessions collected from diverse villages using Distinctness, Uniformity, and Stability (DUS) guidelines. Study Design:  Statistical tools including one-way ANOVA were employed to evaluate variability among accessions. Place and Duration of Study: The survey to obtain different accessions of Coorg mandarin was conducted in Kodagu district of Karnataka. Survey of all the potential orchards were carried out during the fruiting periods from December 2022 to November 2023. Methodology: During the survey general information about the orchard management was noted from the farmers. A total of seventy-three accessions were collected from different villages of the Kodagu district of Karnataka. One way ANOVA was used to analyze the morphological data obtained in the study. R version 4.3.0 used for the Analysis of variance for the fruit parameters and for estimation of genetic variability parameters. Results: Out of the total 73 accessions, erect growth habit was predominant (79%), and a majority (75%) exhibited concave fruit base. Fruit apex shape was evenly split between truncate (52%) and depressed (48%). Greenish-yellow fruit color was observed in 70 per cent of accessions, and 85 per cent of fruits were easy to peel. Only seven accessions had fruit diameters more than 7 cm, and two accessions had long fruit lengths (>6.5 cm). Genetic variability analysis of Coorg mandarin accessions revealed that fruit weight exhibited the highest genotypic and phenotypic variance, heritability and genetic advance, indicating its strong genetic control and suitability for yield improvement through selection. Dendrogram showed two major clusters, highlighting considerable phenotypic diversity within the population. This indicates a strong potential for improvement through selection Conclusion: Significant morphological diversity was observed, notably in tree habit, fruit size, rind color, and peelability, underscoring the rich genetic variation within the region. These findings provide a vital foundation for the conservation, breeding, and improvement of Coorg mandarin varieties and highlight the effectiveness of DUS characterization for cultivar identification and plant variety protection.