Abstract:

As a multi-functional tree species, Cyclocarya paliurus is mainly distributed in the subtropical regions of China. To screen out clones or varieties with stronger cold resistance, we explored the physiological response of C. paliurus clones to cold acclimation and their relationship with cold resistance to provide theoretical references for directional cultivation and cold resistance identification of C. paliurus. Using current-year branches sampled from 19 clones and the liping provenance (CK-LP) of 3-year-old C. paliurus, we measured the mass fraction of water, soluble protein, soluble sugar, starch, lignin, and hemicellulose after cold acclimation, identified the freezing injury of the plants after winter for each clone, and calculated their freezing injury indices. Correlations between physiological indicators and freezing injury indices were analyzed, and a preliminary evaluation of cold resistance was performed for the 19 clones. Our results revealed significant differences in the mass fractions of water, soluble proteins, soluble sugars, starch, lignin, and hemicellulose among the current-year branches of the tested clones. Based on the freezing injury index, cluster analysis divided the tested C paliurus clones into four categories: one superior cold resistant clone (CP3), 10 good cold resistant clones (LF1, Y1, LC4, L1, CR4, J1, LC2, CR5, CR2, and BA1), four moderate cold resistant genotypes (three clones (Q4, LS3, CP6), one provenance (CK-LP), and five weak cold resistant clones (LS2, S4, CR6, LC1, and LS5). The correlation analysis indicated that the water mass fraction in the branches was positively correlated with the freezing injury index, whereas the mass fractions of soluble proteins, starch, lignin, and hemicellulose were negatively correlated with the freezing injury index. Overall, after cold acclimation, the water and soluble protein mass fractions in the current-year branches could be used as the main indicators for the early selection of clones with strong cold resistance, whereas the mass fractions of starch, lignin, and hemicellulose could be used as reference indicators. Among the tested clones of C. paliurus, clone CP3, with superior cold resistance, can be used as the preferred clone for breeding, whereas the other ten clones with good cold resistance are potential breeding materials in the future.

Key words: Cyclocarya paliurus, cold acclimation, physiological response, freezing injury index, cold resistance evaluation, field identification method

摘要：

青钱柳（Cyclocarya paliurus）是多功能树种，主要分布在中国亚热带地区。为筛选出抗寒性较强的品种，探究了青钱柳无性系对寒驯化的生理响应及其与抗寒性的关系，旨在为青钱柳人工林的定向培育及抗寒性鉴定提供理论参考。以寒驯化后19个青钱柳3年生无性系及黎平种源（实生苗）的当年生枝条为材料，通过测定青钱柳枝条水分质量分数、可溶性蛋白、可溶性糖、淀粉、木质素和半纤维素质量分数以及田间试验鉴定，计算了不同青钱柳无性系的冻害指数，分析了各生理生化指标与冻害指数相关性，评价了青钱柳无性系的抗寒性。结果表明，寒驯化后枝条水分质量分数、可溶性蛋白、可溶性糖、淀粉、木质素和半纤维素质量分数在青钱柳无性系间存在显著差异；根据冻害指数，聚类分析将参试青钱柳无性系的相对抗寒性分为4类：1个抗寒性强无性系（CP3）、10个抗寒性较强无性系（LF1、Y1、LC4、L1、CR4、J1、LC2、CR5、CR2和BA1）、3个抗寒性中等无性系（Q4、LS3、CP6）和黎平种源以及4个抗寒性弱无性系（LS2、S4、CR6、LC1、LS5）。相关性分析表明，枝条水分质量分数与冻害指数呈极显著正相关，而可溶性蛋白质量分数、淀粉质量分数、木质素和半纤维素质量分数与冻害指数呈显著负相关。总体看，青钱柳经过寒驯化后，当年生枝条水分质量分数和可溶性蛋白质量分数高低可作为早期筛选抗寒性强优良无性系的主要参考因子，而淀粉、木质素和半纤维素质量分数可作为筛选的辅助参考因子。供试的19个青钱柳无性系中，无性系CP3的抗寒性相对强，可作为青钱柳抗寒性选育的首选材料，而10个抗寒性较强无性系可作为潜在的选育材料。

关键词: 青钱柳, 寒驯化, 生理响应, 冻害指数, 抗寒性评价, 田间鉴定法