日本红枫春季叶片色彩评价

【目的】探讨日本红枫品种群间的叶色关系及其时空分布规律,为挖掘和创制日本红枫特异种质以及叶色育种提供参考。【方法】利用英国皇家园艺学会(RHSCC)比色卡和色差仪对28个日本红枫品种的春季叶色进行了动态测定,通过构建L^*(色调角)三维动态分布图,聚类分析及色彩参数分析,进行日本红枫春季叶片色彩变化规律分析及叶色综合性评价。【结果】供试各品种叶色在^*、C^*和h^*3个维度皆呈规律性空间分布特点和阶段性变化趋势。叶色聚类分析树状图结果将28个日本红枫品种划分为3大色系和6个子色系类群,色系/子色系类群之间具有明显不同的色彩参数特征,3大色系品种叶色变化程度差异显著。【结论】4月下旬为日本红枫春季最佳观赏时期;在3大色系中,色彩律动程度从大到小依次为紫红色系、绿色系、黄色系;选择特异种质为杂交亲本,对今后高稳定性、高观赏性红枫定向育种具有重要参考价值。

Evaluation of leaf colors of Japanese maples in spring

【Objective】The Japanese maple (Acer spp.) is an excellent foliage tree species. The previous research has be focused on the change rule or mechanism of leaf color changes in Acer spp. in autumn. This study explored the relationship between the leaf color and the change rule in Japanese maple cultivars for their spatial and temporal distributions, and aimed to provide a reference for discovering and creating color-specific leaf germplasms.【Method】The colors of 28 Japanese maple cultivars were dynamically measured (S1. April 15; S2. April 30; S3. May 15) by using the Royal Horticultural Society Colour Chart (RHSCC) and a colorimeter. The differences between leaf color determination methods were compared through a correlation analysis. Japanese maple spring leaf colors were analyzed via a lightness (L^*), chromaticity (C^*) and hue (h^*) three-dimensional dynamic distribution map and clustering and color parameter analyses were conducted to evaluate the change rule and breeding strategy.【Result】① A significant correlation (P < 0.000 1) was observed between the color parameters measured by the chromatogram and the RHSCC, but the coincidence was not high (R² = 0.54-0.74). ② During leaf color change (S₁-S₂-S₃), L^* and C^* rose and then fell, with a peak value in the S₂ period. The optimal hue values for ‘best viewing’ (h^* between 20°-40° (red), 70°-80° (yellow), 90°-110° (green)] appeared during the S₂ period. ③ The leaf color cluster analysis showed that the 28 Japanese maple varieties were clustered into three major color groups with six sub-groups. There were significant differences in color parameters between groups and sub-groups. Group one, green (A), included the A₁ green and A₂ dark green sub-groups. The color varieties in A₁ were bright and had ornamental values (C^*. 51.17±2.01; L^*. 62.72±3.76). Group two, yellow (B), only had one sub-group, whose color was bright (C^*. 60.60±0.47; L^*. 75.79±1.70). Group three, purplish-red (C), included the C₁ dark purplish-red, C₂ bright red, and C₃ deep purplish-red sub-groups. The color of varieties in the C₂ sub-group was bright (C^*. 26.2 ± 3.36; L^*. 38.25 ± 2.08). ④ The leaf color of the three color lines changed from light to thick then back to light. The leaf color of the second stage (S₂-S₃) was larger than that of the first stage (S₁-S₂). In different stages of the color systems, the color rhythmicity of the purplish-red was best (ΔE' = 15.33) followed by green (ΔE' = 13.94) then yellow (ΔE' = 9.34). The yellow varieties, ‘Dream of Orange’ and ‘Jingui’, maintained high color saturation and brightness in spring (C^* and L^* reached 60.61 and 75.79, respectively) and had a high ornamental value. The color intensity of the three color groups showed a trend from light to strong and then to light. The range of leaf color parameters in the second stage (S₂-S₃) was larger than that in the first stage (S₁-S₂), but the difference between these stages was not significant and showed a nearly equal changing rate. The color difference of purplish-red color group was the highest (ΔE'=15.33), followed by the green (ΔE'=13.94) then yellow (ΔE'=9.34) color groups. The yellow color group, including A. palmatum ‘Orange Dream’ and A. palmatum ‘Katsura’, maintained high color saturation and brightness (C^* and L^* values reached 60.61 and 75.79, respectively) and had a high ornamental value.【Conclusion】The best spring viewing period for Japanese maple is late April. The leaf color differences are most pronounced in the purplish-red color group, followed by the green group. Color differences are the least pronounced in the yellow group. The selection of specific germplasms to be used as hybrid parents may play an important role in directional breeding of high-stability and high-ornamental Japanese maple trees. These results indicate that A₁ and A_2-1 could be used as parents for bright green color breeding and C₂ and C_1-1 could be used as parents for purplish-red color breeding.