美洲黑杨无性系木材纤维性状遗传变异

【目的】美洲黑杨是苏北地区栽植面积最大的用材树种之一,具有重要的经济价值和生态价值。近年来,随着市场对杨树木材需求量的增加及质量要求的提高,对杨树材性改良的研究迫在眉睫。材性性状中,纤维长度、纤维长宽比等性状值的大小直接影响杨木制浆性能和造纸质量。通过对美洲黑杨无性系木材纤维性状遗传变异的研究,了解杨树木材纤维性状的遗传变异规律,为杨树材性改良及新品种选择提供科学依据。【方法】以泗洪县林场11个美洲黑杨无性系10年生对比试验林为材料,选取各无性系在各区组的标准株,测量其胸径和树高后,伐倒并在离地1.3 m处截取圆盘带回实验室气干备用。试样经脱木素试剂处理后,分别用光学显微镜及纤维形态自动分析仪(MORFI)测量其纤维长度和纤维宽度,计算得到纤维长宽比。将两种测量方法得到的数据进行回归分析,确定回归方程,使后续大规模测定的数据更加精确。使用SPSS 19.0对获得的数据进行分析处理,得到各纤维性状的遗传变异规律和性状间相关关系。采用K-means法对11个无性系进行聚类分析,选取纤维性状和生长性状均表现优异的无性系。用R语言作图,进行数据可视化表达。【结果】用两种测量方法测得的纤维长度、纤维长宽比回归分析R²值均大于0.9, MORFI测量值可靠。纤维长度和纤维长宽比的大小均随林龄增加而增加。11个无性系纤维长度、纤维宽度和纤维长宽比的平均值分别为1 107.8 μm、22.3 μm和49.57。3个纤维性状在无性系间存在显著差异,区组间差异不显著;纤维长度、纤维宽度和纤维长宽比性状的遗传力分别为0.764、0.832和0.590。3个纤维性状在第3、6、9龄间表现出高度相关。纤维长度与生长性状间的相关系数为0.21~0.25,纤维宽度与生长性状间相关系数处于0.39~0.48;纤维长宽比与生长性状间相关系数为-0.07~-0.02。11个无性系可分为3类,其中4-6、4-50、2-2和4-45表现优异,10-34、7-40、7-53和8-9表现次之,7-45、1-20和7-38表现较差。【结论】MORFI(纤维形态自动分析仪)可以快速且较为精确地测量纤维长度和纤维宽度,适合大批量数据的测定,但测定结果需进行回归调整。纤维长度和纤维长宽比随着林龄增大而增加,说明随着林龄的增加,木材制浆性能增强。美洲黑杨无性系纤维性状存在遗传变异,且变异受遗传的影响大于受环境的影响。各纤维性状在幼林第3龄与中林第6龄和成林第9龄间相关密切,且为正相关,对美洲黑杨纤维性状的选择可在林木生长早期进行。美洲黑杨无性系生长性状与纤维长度、纤维长宽比性状间的相关性不显著,在美洲黑杨纤维用材遗传改良时可采用独立选择方法。11个无性系中,2-2、4-6、4-45和4-50在纤维性状和生长性状方面均表现优异,可进行进一步遗传测定,为新品种选育创造条件。

Genetic variation of fiber traits in Populus deltoides clones

【Objective】Populus deltoides is one of the largest timber species planted in the orthern Jiangsu and it has important economic and ecological value.In recent years,with the increase in market demand for poplar wood and higher requirements for wood quality,the research on poplar wood property improvement is necessary.Among the wood properties,fiber length and ratio of fiber length to width directly affect the pulping performance and paper quality of poplar.In this study,we aimed to investigate the general patterns of genetic variation in fiber traits of P.deltoides and to provide the scientific basis for poplar wood improvement.【Method】Eleven ten-year-old P.deltoides clones were used as materials.Sample trees of each clone were selected in each of the four blocks.After measuring the tree height and diameter at breast height(DBH),sample trees were cut down and the wooden discs were intercepted at 1.3 m from the ground and brought back to the laboratory for air-drying.After the samples were treated with the delignification reagent,the fiber traits were measured by optical microscope and MANUEL MORFI.The SPSS 19.0 software was used to analyze and process the data,and the genetic variation and correlation of each trait were analyzed.The K-means method was used to cluster the 11 clones,and among them,the clones with excellent fiber and growth characters were selected.【Result】The regression analysis of values measured by the two methods showed that R^2 were more than 0.9,thus the MORFI measurement values were reliable.The fiber length and fiber length to width ratio increased with the increase of forest age.The average values of fiber length,fiber width,and fiber length to width ratio of 11 clones were 1107.8μm,22.3μm and 49.57,respectively.There were significant differences in fiber traits among different clones.The heritability of the three fiber traits was 0.764,0.832 and 0.590,respectively.The correlation coefficients between fiber length and growth character were between 0.21 and 0.25,and those between fiber width and growth character were between 0.39 and 0.48.The correlation coefficients between fiber length to width ratio and growth character were between-0.07 and-0.02.Eleven clones could be classified into three categories.【Conclusion】The MANUEL MORFI is able to quickly and accurately measure fiber length and width,which was suitable for the measurement of mass data,but the results had to be adjusted by regression.The values of fiber length and ratio of fiber length to width increased with the increase of forest age,which implies that the pulping performance of wood was better with the increase of forest age.Correlation coefficients between different ages were high.These results provided a possibility for early selection of fiber traits in P.deltoides.Genetic variations in fiber traits were observed in different clones,and the heritability of each trait ranged from 0.366 to 0.832.The independent selection method could be used for genetic improvement of P.deltoides.Among all 11 clones,2-2,4-6,4-45 and 4-50 had better fiber and growth properties than those of the rest,and these clones should be further tested to create conditions for new breeding.