砂生槐天然种群种实形态和萌发特征地理变异

Geographical Variation of the Seed and Germination Characteristics of Natural Populations of Sophora moorcroftiana

为了更好地开展砂生槐(Sophora moorcroftiana)种质资源收集及保存工作,探究砂生槐种实性状和种子萌发性状的地理变异特征,在西藏砂生槐自然分布区挑选具有代表性的天然种群12个,测定了包括种长、种宽和种子发芽率在内的15项种实性状指标,运用巢式方差分析、相关分析及聚类分析研究了砂生槐种实、萌发性状的变异水平及其与地理因子的相关性。结果表明:1)种群间和种群内种实性状均存在显著性差异(P<0.05),种群间种子长宽积的差异最大,说明各种群的种子大小差异很大,而种群间的种长差异最大。在表型变异程度上,种群内的变异(21.91%)略大于种群间的变异(18.30%),其中种群平均表型分化系数为45.51%;这表明砂生槐的表型变异不仅仅受到遗传因素的影响,而且很大程度上受到了环境因素的调控。2)发芽率、发芽势、发芽指数和活力指数4个性状间均呈极显著正相关,发芽指数与种宽和种子长宽积呈显著相关,说明种子越饱满,发芽能力越强。3)种长、种子长宽积、荚果宽度、发芽势、发芽指数和活力指数等与海拔呈显著正相关,与经度呈显著负相关,表明砂生槐的种实大小和萌发能力从东部低海拔地区到西部高海拔地区呈上升趋势,可对高海拔优良种群加以开发利用,所有性状与纬度均无明显的相关性。4)运用ward s对砂生槐种群进行聚类分析,12个砂生槐种群大致可以划分为高海拔和低海拔2个亚群。中、高海拔亚群(3586~4207 m)的种子更饱满,千粒重更大,萌发能力更强,而中、低海拔亚群的幼苗长度、胚根长度和侧根数更高。

In order to better collect and preserve the germplasm resources,and to explore the geographic variation pattern of seed and germination traits of Sophora moorcroftiana,an important domestic shrub occurring in Tibet,12 representative nature populations of S.moorcroftiana were selected and 15 indexes related to seed trains were measured,such as seed length,width,and germination rate.The correlation between the variation level of seed and germination traits with the geographic factors were studied by the Nested variance analysis,correlation analysis and cluster analysis.The results showed that:1)there were significant differences in seed traits among and within populations(P<0.05).The largest variation in seed length and width among populations revealed that the seed size in different populations was of great difference,and the difference of seed length within populations was the largest.In the degree of phenotypic variation,the variation within the population(21.91%)was slightly larger than the variation among populations(18.30%),and the average phenotypic differentiation coefficient of the population was 45.51%,which indicated that the phenotypic variation was not only affected by genetic factors,but also by environmental factors in great extent.2)Correlation analysis indicated that there existed extremely significant and positive correlations among the germination rate,germination potential,germination index and vigour index,and there were significant and positive correlations among the seed germination index and seed length and width product,indicating that the more plump of the seed,the higher germination rate.3)Correlation analysis between seed and germination traits and geographic factor indicated that the length of seed,length and width product,pod width,germination potential,germination index and vigor index were significantly and positively correlated with altitude,and negatively correlated with longitude,it indicated that the seed size and germination ability were increasing from the low altitude areas in the east to the high altitude areas in the west,and there were no significant correlation between all traits and latitude.4)Using Ward s cluster analysis,12 populations could be roughly divided into two subgroups of high altitude and low altitude.The seeds of the high-altitude subgroup(3586-4207 m)were more plump,the 1000-seed mass was larger,the germination ability was stronger than those of low-altitude subgroup,but the seedling length,radical length and lateral root number of the low-altitude subgroup were higher than high-altitude subgroup.