宁夏贺兰山杜松天然群体的表型多样性

Phenotypic diversity for natural populations of Juniperus rigida in the Helan Mountains of Ningxia

为了研究杜松Juniperus rigida天然群体在宁夏贺兰山自然保护区内的表型变异程度和变异规律,共调查了6个杜松天然群体,对针叶、球果、种子、树高、胸径和树干通直度等20个表型性状进行了比较分析,并采用方差分析、多重比较、相关分析和聚类分析等多种分析方法,对群体间和群体内的表型多样性进行了讨论。结果表明:杜松表型性状在群体间和群体内存在极其丰富的变异,群体间共有11个性状指标达到极显著水平(P<0.01),群体内共有7个性状指标达到极显著水平(P<0.01)。表型分化系数即群体间变异为66.63%,大于群体内的变异(33.37%),群体间变异是杜松表型变异的主要部分。20个表型性状间多数呈极显著(P<0.01)或显著(P<0.05)相关。杜松表型性状与生态因子相关分析表明,其表型变异呈梯度规律性,随着海拔的升高,针叶宽逐渐增大;随着郁闭度的增加,针叶长和一级侧枝总数都逐渐增大;枝下高随着坡度的增大而增大。通过表型性状的聚类分析可以将杜松6个群体划分为4类。

To determine the phenotypic variation for natural populations of Juniperus rigida and the relationship between phenotypic variation and different population distribution areas,six populations and 120 families were sampled in the Helan Mountain Nature Reserve of Ningxia.Twenty phenotypic traits were analyzed,including needles,cones,seeds,height,diameter at breast height（DBH）,crown diameter,height-diameter ratio,crown-diameter ratio,density of primary branches,height of stem under branch,stem straightness,total number of primary branches and length,and diameter of primary branches using variance analysis,correlation analysis,and the Unweighted Pair Group Method with Arithmetic Mean（UPGMA）hierarchical cluster analysis.Results showed that significant differences（P0.01） among populations for 11 characteristic indices,such as needle length/needle width,cone length,cone width,cone length/cone width,seed length,seed width,seed length/seed width,DBH,stem straightness,height-diameter ratio,crown-diameter ratio,total number of primary branches,diameter of primary branches,and height of stem under branch.Also within populations,seven characteristic indices were significantly different（P0.01）,such as needle length,needle width,needle length/needle width,cone length,cone width,seed width,and seed length/seed width.Variation among populations mainly contributed to phenotypic variation with a mean phenotypic differentiation coefficient（Vst） of 66.63%;whereas within populations,VST was 33.37%.For correlations between needle length and total number of primary branches,canopy density was positively and significantly（P0.05）correlated;for needle width,altitude was significant（P0.01）positive correlated;for height of stem under branch,gradient was significant（P0.05） positive correlated;for needle width,slope direction was significant（P0.05）negative correlated;In addition,six populations gathered into four groups by cluster analysis,which inconsistent with the geographic distribution and altitude gradient of Juniperus rigida in the Helan Mountains.There were significant differences in phenotypic variation among and within populations.Utilizing of variation within and among populations is important significance for genetic improvement of Juniperus rigida.