Variation in anatomical and chemical properties in different clones of Casuarina junghuhniana and its hybrids

Casuarinas are extensively cultivated across tropical, subtropical, and Mediterranean regions due to their rapid growth, adaptability to diverse environmental conditions, multifaceted utility, and suitability for short-rotation agroforestry systems. This study investigated clonal variation in elite Casuarina germplasm obtained from the Institute of Forest Genetics and Tree Breeding (IFGTB), Coimbatore, and planted under subtropical conditions in Punjab, India. The focus was on examining wood properties at different tree heights (base, 25%, 50%, and 75%) in a six-year-old plantation. Standard methods recommended by the Technical Association of Pulp and Paper Industry (TAPPI) were employed to assess the wood characteristics. The results revealed significant variability in wood properties among clones. Clone IFGTB CH 6 exhibited the highest mean fibre length (1068.6 μm), while clone IFGTB CH 2 demonstrated the largest fibre diameter (19.16 μm). Clone IFGTB CH 4 had the longest vessel length (512.78 μm), while IFGTB CH 6 exhibited the widest vessel diameter (189.90 μm). In terms of longitudinal distribution, the maximum average fibre length was recorded at the tree base, while the largest fibre diameter was observed at 75% of the tree height. With regard to chemical composition, clone IFGTB CH 2 recorded the highest holocellulose content (64.40%), while IFGTB CJ 108 had the lowest lignin content (31.24%), making it particularly suitable for pulp and paper production. The distribution of holocellulose and lignin content along the height of the tree showed that the maximum holocellulose was found at 75% of the tree height, while the lowest lignin content was observed at the tree base. These findings highlight the considerable variation in wood properties across clones and vertical tree height, with clone IFGTB CH 6 standing out as a promising candidate for woodbased industries due to its superior fibre dimensions, high holocellulose content, and relatively low lignin content. The observed clonal variability in wood properties offers significant potential for advancing tree improvement programs aimed at enhancing the performance of Casuarina in industrial applications.