关键词: 柏木, 无性系, 家系, 生长变异, 生物量, 含碳量, 异速生长方程

Abstract: Objective This study aims to explore the early growth and carbon sequestration potential of cypress clones and families, so as to lay the foundation for the selection and breeding of fast-growing and high carbon sequestration varieties. Method The 9-year-old clonal and family test forests established in Kaihua County Forest Farm, Zhejiang Province, were used as materials to analyze the variation pattern of growth traits, analyze the distribution difference of biomass and carbon content, construct the allometric growth equation of carbon content, and analyze and estimate the carbon fixation potential. Result The growth advantage of cypress clones was obvious, and the average tree height, DBH and individual volume were 47.81%, 28.39% and 120.83% higher than those at the family level. There were significant differences in tree height, diameter at breast height and individual volume between clones and families (P<0.01). Regardless of the level of families and clones, diameter at breast height and tree height were significantly positively correlated with biomass and carbon content, and had no significant linear relation with carbon content rate. The proportion of biomass allocation of cypress trunk was the highest, with the highest proportion of carbon content, while leaves had the highest carbon content rate. Clones maintained their growth advantage mainly by sacrificing the biomass distribution of coarse roots (3.45% lower than that of families), increasing the biomass of branches (5.55% higher than that of families) and fine roots (1.34% higher than that of families). The fitted carbon content model (lnTBS=k₀+k₁lnD+k₂lnH+k₃lnUBH) had the best prediction effect with tree height, DBH and the height under branches as independent variables (except for the carbon content of clone roots). The estimation accuracy was able to be improved by including the height under branches as independent variables in the model. According to the selection rate of 20%, it was estimated that the genetic gain of carbon content in the clonal test forest was 51.48%, and that in the family test forest was 16.14%. Six clones and families with fast growth and excellent carbon fixation were selected by combining the volume traits. Conclusion Cypress clones have higher carbon fixation capacity than families, and their carbon fixation capacity can be improved by screening good growing genotypes. At the early growth stage, the height under branches as an important evaluation index is used to construct the allometric growth model, which is helpful to improve the estimation accuracy of plant carbon content. In combination with the growth characteristics, clones and families with fast growth and high carbon content can be screened to improve the carbon fixation potential of cypress.

Key words: cypress, clone, family, growth variation, biomass, carbon content, allometric growth equation