Abstract:

To screen suitable new superior southern-type black poplar clones for cultivation in the Jianghan Plain and accelerate the renewal of improved poplar varieties in the region, this study used the currently dominant elite cultivars ‘Danhong Yang’ and ‘Nanlin 895’ as controls. Twelve black poplar clones selected through early screening were evaluated. Through the 8-year positioning test from 2017 to 2024, the growth indexes such as diameter at breast height (DBH), plant height and volume of different forest ages were measured. Combined with the stem straightness, variance analysis, genetic parameter estimation and selection index method were used to evaluate the excellent clones. The results showed that extremely significant differences (P<0.01) existed in DBH and tree height among the 14 tested clones (including controls) at all ages. Volume at 8 years also showed highly significant differences, the individual tree volume of maximum clone at 8 years was 3.87 times that of the minimum clone. Growth rates for DBH and height varied significantly among clones over the 8-year period. Some clones exhibited faster growth in the first 2 years, others accelerated between years 3-4, and some showed rapid growth primarily from years 5-8. Net increment data for DBH, height, and volume at different ages revealed distinct growth patterns for southern-type black poplar in the Jianghan Plain. Fast-growth period occurred from 1 to 4 years post-planting for DBH, fast-growth period peaked between years 3-4 for height, fast-growth period spanned years 3-6 for volume. The repeatability of DBH, plant height and 8-year-old volume were 0.85-0.92, 0.89-0.92 and 0.88, respectively, which were all high repeatability traits. Based on growth indicators (at 8 years) and stem straightness, three clones (‘HB-3650’, ‘08-01-52’ and ‘08-01-41’) outperforming the control ‘Danhong Yang’ were selected from the 12 tested clones, representing a selection ratio of 25%. This study provides high-quality materials for the regeneration of poplar varieties in Jianghan Plain. In the future, comprehensive trait evaluation can be further carried out in combination with stress resistance, wood quality and other traits to accelerate the popularization and application of excellent clones.

Key words: Jianghan plain, southern-type black poplar, superior clone, diameter at breast height, height, stem straightness, evaluation and selection