Variability in wood physico-chemical properties of Juglans regia L. from Indian Himalayan region

This is the authors' abstract. We don't add key points for this paper.

The present study, conducted in the Indian Himalayan region from 2021 to 2023, aimed to explore variations in the physico-chemical properties of wood in wild genotypes of Juglans regia, given the rising global demand for premium walnut wood. Wood samples were extracted at a depth of 5–7 cm in from the stem maximum diameter at breast height (DBH) for analysis. Significant variation (P < 0.05) among genotypes was observed in parameters such as DBH, tree height, specific gravity, bark per cent, alcohol-benzene extractives, and cold-water solubility, with high coefficients of variation, indicating their potential for genotype characterisation. Tree height showed a significant positive correlation with latitude (r = 0.31), fibre length (r = 0.98), and wood percentage (r = 0.55), whereas it was negatively correlated with bark percentage (r = −0.55). The lignin content was positively correlated with alcohol-benzene extractives (r = 0.76) and negatively correlated with holocellulose content (r = −0.80). Principal component analysis revealed that tree height, fibre length, wood percentage, lignin content, holocellulose content, and solubility traits accounted for 81% of total variation across five principal components (eigenvector score ≥ 0.75). Genotypes CHN-I, CHN-II, CHK-I, GSN-V, ANI-I, DML-II, and PLD-I were identified as being superior, offering significant potential for genomic breeding programs to enhance walnut wood quality and growth.