Genetic Variation and Elite Clone Selection in Gmelina arborea for Seed Source Development in Northeast India
Gmelina arborea Roxb., a fast-growing timber species of tropical Asian origin, holds significant potential for industrial plantations inNortheast India. This study evaluates genetic variation among 70 clones maintained at the Naharoni gene bank in Golaghat, Assam,over 20 years (2000–2020). Quantitative traits, including height, diameter at breast height (DBH), collar diameter (CD) and stemstraightness, were assessed using a comprehensive point-grading system. Significant variation occurred across all traits (p<0.01), withcoefficients of variation (CV) from 14.35% (CD) to 24.91% (straightness). Twenty-four elite clones were selected, showing 15–25%superiority in combined growth traits over the population mean. Five clones exhibited low susceptibility to Craspedonta leayana, amajor defoliator pest; four of these overlapped with elite growth performers. Phenotypic (PCV) and genotypic (GCV) coefficients ofvariation yielded high broad-sense heritability (h² = 0.62–0.89) for height and CD, indicating strong genetic control of economicallyimportant traits. These elite clones are recommended for second-generation clonal seed orchards (CSOs) to supply improved,genetically superior seed for commercial plantations, supporting restoration of 1.2 million hectares of degraded lands in NortheastIndia.