Studies on the correlation between the branch and leaf morphological variation of Diplopanax stachyanthus and the environmental factors

Nine natural populations of Diplopanax stachyanthus,which belongs to the Grade II state-protected endangered plants,were sampled from Hunan,Guangdong,Guangxi,and Yunnan provinces.Variation of 20 morphological characters within and between populations was measured,and the correlations among morphological characters,and between these characters and environmental factors,were investigated.In addition,UPGMA-based cluster analysis and principal components analysis(PCA)were performed using the phenotypic data.The results revealed morphological variation within and among the populations of D.stachyanthus.Among the nine populations,the highest mean value of all measured morphological traits,especially that of branch traits,occurred in the two Huaping populations(HP1,HP2).The mean variation coefficients also varied among populations,with the ordering of NL2MS2FDMS1EHZHP2HP1 DYSNL1.The variance analysis revealed significant among-population variation in 13 morphological characters(P0.05,0.01 or 0.001,respectively),with F values ranging from 0.184 to 31.788.Pearson correlation analysis showed that the correlation was high among vegetative organs.The environmental factors,including average temperature in January,minimum temperature,annual average temperature and soil organic matter,could significantly affect the growth of D.stachyanthus.Cluster analysis showed that the morphological differentiation was not correlated with the geographic isolation among populations.PCA analysis resolved three principal components that explained 66% of the total variation.