Abstract: [Objective] Structural difference of resin canal in young stem, un-wounded and wounded trunks among Pinus massoniana clones with different resin yield were studied in order to provide theoretical basis for early selection of high resin yielding clones.[Method] Six clones of P. massoniana with different resin yield were measured using plant paraffin sections to compare differences of xylem anatomy between young stem and trunk and to investigate the structural changes due to wounding to the trunk. And correlations of resin canal structure among young stem, wounded and un-wounded trunks were analyzed.[Result] The total area of axial canals per unit area and the average area of individual axial canals in young stems were significantly different between high and low yielding clones. The total area of axial canals per unit area and the average area of individual axial canals of high yielding clone were 63 433 μm²·mm^-2 and 4 832 μm², 2.69 and 3.03 times greater than the low yielding one. The total area of radial canals per unit area and the average area of individual radial canals of high yielding clones were 42 105 μm²·mm^-2 and 3 858 μm², 3.19 and 3.44 times greater than the low yielding one. However, the difference of frequencies of axial canals was not significant between high and low yielding clones. Similar difference was found in un-wounded trunks. The total area of axial canals per unit area and the average area of individual axial canals of high yielding clone were 96 229 μm²·mm^-2 and 17 656 μm², 12.15% and 14.54% more than the low yielding one. And the difference of frequency of axial canals was not significant between high and low yielding clones. In the wounded xylem, the total area and number of axial canals per unit area (118 635 μm²·mm^-2 and 7.9) of high yielding clone were 23.96% and 27.87% higher than those of the low yielding one. However, the difference of the average area of individual axial canals was not significant between the high and low yielding clones. In the un-wounded trunk, the resin canals are mainly distributed in latewood and transition area between early- and late-wood. And the average width of latewood in high yielding clones was 312 μm, 15.56% greater than that of the low yielding ones. Influenced by wounding, resin canals were induced in early wood, leading to increase of the total area and number of resin canals in the xylem. However, the increase was higher in the high-yielding clone than in the low-yielding clone, resulting in higher resin yield in the high-yielding clone when wounded. The total area of resin canals in young stem was significantly correlated to that in wounded and un-wounded trunks, with correlation coefficients of 0.533 and 0.444 respectively.[Conclusion] There was significant difference in total area of axial canals between high and low yielding clones. The difference of resin canals in trunk xylem could be predicted by the anatomic characteristics of young stems, indicating possibility of early selection of high resin yielding clones of P. massoniana.

Key words: Pinus massoniana, resin yield, clones, xylem, resin canal, wound, anatomy