Aquilaria malaccensis Lam. is commonly known as Agarwood which is distributed in the Indo-malesian genus Aquilaria of family Thymelaeaceae known to produce resin-impregnated heartwood that is fragrant and highly valuable. Agarwood is reputed to be the most expensive wood in the world. Twenty two open pollinated families in A. malaccensis were selected and evaluated for growth attributes and genetic divergence. The experiment was conducted at Forest College and Research Institute, Tamil Nadu Agricultural University; Mettupalayam situated at 11° 19’ N longitude, 76° 56’ E latitude at 300 MSL during January - December 2010. The study indicates significant differences among the selected families for various growth attributes. Among the twenty two progenies evaluated, three progenies viz., NHJA, KHOW-1 and CHEK-1 exhibited consistent superiority over growth periods for shoot length, collar diameter and number of branches. Genetic divergence studies resulted in grouping of the selected families into six clusters which indicated the existence of adequate genetic divergence. Among the clusters, cluster VI was the largest with 9 progenies while the maximum intra clusters distance was recorded in cluster V. The intra and inter cluster distance revealed that maximum inter cluster distance was recorded between cluster IV and V which indicated the presence of wide genetic distance between A. malaccensis progenies. Among the various growth attributes, number of branches contributed maximum towards genetic divergence followed by shoot length. These two characters could act as a reliable indicator for future improvement programme in this economically important species. Genetic analysis of the progenies indicated adequate variability in the population. The phenotypic co-efficient of variation (PCV) and genotypic co-efficient of variation (GCV) estimates exhibited superiority of number of branches followed by shoot length and collar diameter. In case of shoot length, collar diameter and number of branches exhibited moderate heritability. The genetic advance was high for shoot length followed by number of branches which indicated the reliability of these two parameters for inclusion in future improvement programme.
Key words: Aquilaria malaccensis, provenances, variability, heritability, genetic divergence, intra and inter cluster distance.
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