杉木无性系不同林龄生长变异与选择效应

Growth variation and selection effect of Cunninghamia lanceolata clones at different stand ages

【目的】研究杉木不同林龄无性系生长性状(胸径、树高、材积)的遗传变异规律,探讨早期选择的适宜年龄,为杉木无性系良种再选育提供依据。【方法】从131个杉木无性系每木调查数据中随机选择56个无性系样本,以其5,10,15,20和30年生时测算的胸径、树高、材积数据为依据,进行各性状的变异分析、方差分析、重复力估算,分析各无性系在不同林龄的遗传变异规律;采用早晚相关性分析和聚类分析确定早期选择的适宜林龄;利用聚类分析和布雷金多性状综合评定法选择出杉木速生无性系,并通过计算遗传增益和现实增益对选择效果进行评价。【结果】杉木无性系的胸径、树高、材积性状具有丰富的变异,变异幅度分别为11.82%~24.41%,10.56%~21.28%和30.83%~66.73%,表现为材积>胸径>树高;方差分析结果显示,杉木胸径、树高、材积在无性系间差异极显著,且重复力达0.919~0.947。相关分析认为,杉木无性系生长性状早晚相关性呈极显著正相关,表型相关系数为0.432~0.999;各生长性状间的相关性与林龄间隔期有关,间隔期越短其相关性就越紧密。聚类分析结果表明,与30年生时入选的速生无性系比较,在林龄15年生时进行选择的正选率达85.71%,而错选率为14.29%,漏选率为0%。30年生时6个速生无性系胸径、树高、材积的总体遗传增益分别为21.86%,18.32%和61.19%,现实增益分别为29.86%,24.93%和92.92%。布雷金多性状综合评价以无性系79172(1.705)最大,然后依次是7911(1.698)、8213(1.688)、8237(1.672)、79173(1.666)、8219(1.664)。【结论】杉木无性系间的生长性状存在丰富的遗传变异,且受到较高的遗传控制,有较好的遗传改良潜力。15年生是杉木速生无性系进行适宜选择的最早年龄,此时进行优良无性系选择更有利于提高杉木遗传改良的效率。30年生按照<5%的入选率,无性系79172和7911被选择出来,适宜在湖南永州林区进行推广种植。

【Objective】This study investigated the genetic variation of growth traits(DBH,height and volume)of Cunninghamia lanceolata clones at different stand ages and explored suitable age for early selection to provide basis for rebreeding of fine varieties.【Method】A total of 56 samples from 131 C.lanceolata clones were randomly selected from the survey data of individual trees.Based on the data of DBH,height and volume measured at ages of 5,10,15,20 and 30 years,the variation analysis,variance analysis and reduplication estimation of traits were carried out to analyze the genetic variation rule of each clone at different stand ages.Early and late correlation analysis and cluster analysis were also used to determine suitable stand age for early selection.Clustering analysis and Bregkin multi-trait evaluation method were used to select fast growing clones and the selection effect was evaluated by calculating genetic gain and realistic gain.【Result】There were rich variations in DBH,height and volume of C.lanceolata clones,with ranges of 11.82%-24.41%,10.56%-21.28%and 30.83%-66.73%,respectively.They were in the order of volume>DBH>height.The results of variance analysis showed that DBH,height and volume of C.lanceolata were significantly different among clones with repetitions of 0.919-0.947.Correlation analysis showed that morning and evening correlations of growth traits were extremely significant and positive with correlation coefficients of 0.432-0.999.The correlation between each growth character was related to stand age interval,and shorter interval led to closer correlation.The results of cluster analysis showed that the positive selection rate was 85.71%,the wrong selection rate was 14.29%,and the omission rate was 0%,compared with the fast growing clones selected at the age of 30 years.At the age of 30 years,the overall genetic gain of DBH,height and volume of 6 fast growing clones were 21.86%,18.32%and 61.19%,while those of actual gain were 29.86%,24.93%and 92.92%,respectively.Based on comprehensive evaluation using Bregin’s multiple traits,79172(1.705)was the best,followed by 7911(1.698),8213(1.688),8237(1.672),79173(1.666)and 8219(1.664).【Conclusion】The growth traits of C.lanceolata clones had rich genetic variation and were controlled by high genetic control,showing good potential for genetic improvement.The age of 15 years was the earliest suitable age for selection of fast growing clones of C.lanceolata to improve efficiency of genetic improvement.The 30-year-old clones of 79172 and 7911 were selected according to the selection rate of less than 5%for popularization in Yongzhou forest area,Hunan.