【目的】研究不同无性系四川桤木1年生嫁接幼苗的生物量及其分配特征,了解不同无性系嫁接幼苗对环境的适应策略和能力,为筛选适宜地区发展的优良无性系提供依据。【方法】采用随机区组设计方法,将苗圃地划分为3个区组,每个区组包含若干个小区。2015年11月将采自四川省宣汉县、恩阳区和金堂县的34株四川桤木优树穗条嫁接于长势基本一致的砧木上,每小区内约嫁接100株(重复3次)。2016年8月中旬测定小区内所有嫁接幼苗的株高和基径,根据测定结果在每个小区内选出3株平均株作为待测植株,测定待测植株不同部位的生物量,采用单因素方差分析和系统聚类分析方法比较不同无性系嫁接幼苗生物量及其分布特征的差异。【结果】四川桤木嫁接幼苗地上部分鲜质量表现为叶>主干>侧枝,叶片和主干相对含水量在50%以上。叶片和主干在地上部分生物量中占比较大,侧枝生物量占比最小;地下部分各根径生物量大小表现为粗根>细根>中根。生物聚类分析表明,34个四川桤木无性系嫁接幼苗可分为3类,其中第2类无性系幼苗总生物量最大,第1类次之,第3类最小。3类无性系幼苗之间生物量分配比较,第2类无性系植株分配给侧枝和细根的生物量最大;第1类无性系植株主干生物量占比较高,而叶片和细根生物量占比最小;地下以第3类无性系植株叶片生物量占比最大,侧枝和主干生物量占比最小,粗根生物量占比最大。【结论】不同无性系四川桤木1年生嫁接幼苗的生物量及生物量分配特征具有一定差异,其中第2类无性系幼苗总生物量最大且各器官生物量分配较均匀,可能对光照条件和土壤水热条件的适应能力最强;第1类无性系总生物量次之,可能对光照条件适应能力较强,但是对土壤水热条件的适应能力不高;第3类无性系总生物量最低,可能对环境的适应能力最低。

【Objective】To understand the adaptation strategies and capabilities of grafted seedlings of different Alnus ledgeriana clones to the environment and select excellent clones for regional development, we investigated the biomass and allocation characteristics of one-year-old grafted seedlings of different clones of A. ledgeriana.【Method】The random block design method was used to divide the study site into three blocks, and each block contained 34 plots. Thirty-four dominant A. ledgeriana were collected from Xuanhan, Enyang and Jintang of Sichuan Province. The spikelets of dominant trees were grafted onto rootstocks with the same growth in November 2015. Approximately 100 rootstocks were grafted in each plot and repeated three times in different blocks. The plant heights and base diameters of all grafted seedlings in each plot were measured in mid-August 2016. Three average plants were selected as the study plants in each plot based on the heights and base diameters. We determined the biomass of each part of the study plants and then analyzed the differences in biomass and its allocation characteristics among different clones using ANOVA and systematic cluster analysis.【Result】The aboveground part of the fresh weight of the A. ledgeriana clones was ranked as leaf > trunk > lateral branch, and the relative water content of each part was more than 50%. The leaf and trunk were the heaviest parts of the aboveground biomass, and the lateral branch was the lightest part. The underground part of the biomass was ranked as rough root > fine root > medium root. Cluster analysis showed that the 34 A. ledgeriana clonal seedlings were divided into three categories. The second category of clonal seedlings had the largest total biomass, then the first category, and the third category was the smallest. The biomass allocation characteristics of the three categories of clonal seedlings were also different. The ratios of the biomass of lateral branches and fine roots in the second category of clonal seedlings were larger than those in the first and third categories. The ratios of the biomass of lateral branches and trunks in the first category clonal seedlings were relatively high, while those of leaves and fine roots in the first category clonal seedlings were lower than those in the second and third categories. The ratio of the biomass of leaves in the third category clonal seedlings was greater than that in the first and second categories, the ratios of the biomass of lateral branches and trunks in the third category clonal seedlings were lower than those in the first and second categories, and the ratio of the biomass of rough roots in the third category clonal seedlings was the largest.【Conclusion】The biomass and allocation characteristics of different one-year-old A. ledgeriana clones were distinct. Among them, the total biomass of the second category clonal seedlings was the largest and their allocation characteristics were evenly distributed, supporting that the second category clonal seedlings may have the strongest adaptability to light and soil hydrothermal conditions. The total biomass of the first category clonal seedlings suggest that they may have relatively strong adaptability to light conditions but relatively poor adaptability to soil hydrothermal conditions. The total biomass of the second category of clonal seedlings was the lowest, indicating that they may have the weakest adaptability to the environment.