Morphometric Diversity Assessment of Acid Lime (Citrus aurantifolia Swingle) Genotypes from Northeast India

Acid lime ( Citrus aurantifolia Swingle) is a tropical citrus species valued for its fruit quality and adaptability. The Northeastern region of India has long been recognized as a secondary center of citrus diversity, harboring genetically rich and diverse acid lime genotypes. This investigation conducted from 2020-2023 at College of Horticulture and Forestry, CAU(I), Pasighat, Arunachal Pradesh, sought to quantify the morphological variation among 30 local acid lime genotypes collected across eight northeastern states of India. Morphological characterization followed the standardized descriptors of the International Plant Genetic Resources Institute for citrus, documenting tree architecture, leaf morphology, fruit attributes, and seed characteristics. Significant variability was recorded across all measured traits. Tree height ranged from 2.68 m to 6.56 m, stem girth from 31.00 cm to 64.55 cm, and canopy spread from 3.37 m to 7.05 m. Leaf lamina length varied between 40.00 mm and 71.22 mm, leaf area from 10.73 cm² to 36.44 cm², and fruit weight from 31.47 g to 91.60 g. Juice yield spanned 15.00 mL to 47.00 mL, while the number of fruits per plant ranged from 100 to 356. The average number of seeds per fruit ranged from 4.00 to 31.00. Genetic variability analysis revealed that the phenotypic coefficient of variation consistently exceeded the genotypic coefficient of variation for all traits. High broad-sense heritability (>90%) was observed for most quantitative traits, indicating strong genetic control. Correlation analysis identified significant positive associations among yield-contributing characters, while principal component analysis extracted five components jointly explaining 78.81% of total variation, with fruit weight, pulp weight, rind weight, and stem girth dominating PC1. Cluster analysis partitioned the 30 genotypes into two major clusters, with genotype CHF-AL-23 forming a uniquely distinct solitary group. The substantial morphometric diversity documented here underscores the considerable potential of Northeast Indian acid lime germplasm for breeding programs aimed at varietal improvement and conservation of genetic resources.