Study On Morphological Diversity And Cadmium Accumulation Of Iris L.

Iris plants have the characteristics of absorbing heavy metals and rich variety.Therefore,it has great application prospects in preventing the soil pollution of heavy metals.In this research,the morphological diversity of 72 Iris varieties was studied by principal component analysis and cluster analysis in Fuyang city,Anhui province.The differences of cadmium accumulation in 10 varieties of Iris under 20 mg/kg cadmium content were systematically studied by pot experiment,and the ultrastructure of 4 Iris varieties was further analyzed.The main results are as follows:(1)Morphologic variation of Iris was abundant,the morphological diversity index is between 0.29 and 2.02,and the average diversity index is 1.54;the phenotypic trait variation coefficient ranges from 22.41% to 48%,and the average variation coefficient is 37.32%.Principal component analysis was performed on 15 phenotypic traits of Iris,and 5 principal components were extracted.The cumulative contribution rate reached 82.78%.The analysis of aggregate hierarchical cluster analysis showed that the phenotypic characteristics of 72 Iris samples could be grouped into two categories.The clustering results of Iris ensata showed that the adaptability of Iris species in Fuyang area of Anhui was weaker than that of Iris sibirica,Iris germanica and Iris louisiana.(2)Cadmium can inhibit the growth of most Irises,but it can promote the growth of Iris tectorum.Iris ensata has the highest cadmium content and total cadmium accumulation,which is 20.46 mg/kg and 60.6 ug,and plant height,leaf width,number of leaves,fresh weight,and biomass are least affected.It is suitable for phytoremediation in cadmium-contaminated areas;Iris tectorum has low cadmium content and promotes growth,and is suitable as a substitute plant in cadmium-contaminated areas;while other varieties have the lowest content of cadmium,which inhibits growth significantly,and is not suitable for planting in cadmium-contaminated areas.(3)The ultrastructural observations found that cadmium can cause the cell wall of the Iris plant cells to separate and deform,and the gap between the yellow Iris cells is significantly increased,and most of the cadmium is gathered outside the cell wall;cadmium can destroy the cell membrane structure and even cause the mitochondrial structure to break,Dissolved,the chloroplast swelled and the membrane structure was dissolved;the nuclear morphology did not change significantly.Mitochondria and cytoplasmic wall structures are more sensitive to heavy metal cadmium than chloroplasts and nuclei.