Electron Probe Microanalysis Studies On Chemical Composition Of Phytoliths In Plants Of The Subfamily Panicoideae In The Early Stage Of Their Growth Season

Phytolith analysis has been used in plant classification,archaeology and paleoenvironment reconstruction widely.At present,the study of Phytolith morphology is in-depth,but the study of chemical composition of Phytolith is rare.In the early part of the growing season,some plants of the Panicoideae?maize?formed many polybate,and the polybate disappears gradually with crops grow.It is uncertainty that the situation is related to the leaf position or the active formation of phytoliths.Electron probes can perform micro-area chemical component analysis for different forms of phytoliths,which may provide chemical evidence for the active formation of phytoliths.The article has done a great deal of research,including analysed Phytolith morphology of maize and five-section awn at the early stage of growths,investigated the chemical component of phytoliths in maize leaves at different growth stages,explored the chemical component of phytoliths in the same leaf position at different growth stages,discussed the changes of the chemical component of the same type of phytoliths in different periods,inquired the relationship between the active?passive?accumulation silicon signal and the formation of phytolith.The results are as follows:?1?The article analysed the morphological group changes of phytoliths at the early stage of growths of maize and five-section awn leaves,and the article also employed the electron probe method to test the changes of the phytolith chemical component of the true leaf in the maize growth cycle.?2?The morphology of phytolith is affected by genes and environment.The bilobate of maize is affected by environment mainly.The first three leaves of maize mainly carry out C₃ pathway photosynthesis,which will produce many polybate with3 leaves and more than 3 leaves.In the case of light insufficient early,the photosynthesis of the C₃ pathway of the 4th and 5th true leaves of maize are enhanced,and some polybate with more than 3 leaves will be produced.In the later stage,the temperature rises and the light is sufficient.The photosynthesis of the C₃ pathway will decrease,and the content of the polybate with more than 3 leaves will decrease rapidly,which can deduce that photosynthesis have an effect on the formation of phytoliths in maize,the photosynthesis of the C₃ pathway is beneficial to the formation of polybate with more than 3 leaves.The shape of the five-section awn bilobate is mainly affected by genes.Whether it is the first three true leaves or the 4th and 5th true leaves,the polybate with more than 3 leaves rarely appears in the phytolith group.?3?Electron probes tested the phytoliths of different leaf positions in different periods of maize,including elongate,cuneiform cell and bilobate,to understand the content of SiO₂,Na₂O,MgO,CaO,P₂O₅,Cr₂O₃,MnO,FeO and K₂O in phytoliths.In the growth stage of maize,with the change of leaf position and time,not only the content of SiO₂ changes,but also other mircoelements.The SiO₂ content of elongate,cuneiform cell and bilobate of the first three true leaves of maize has been declining,which may be related to the slowly decline of the light received by the true leaves.The first three leaves of maize require a short time from germination to the maximum leaf area,and the three true leaves are significantly smaller than other true leaves.In the early stage,The growth rate of maize is very fast.The first three true leaves will be covered by other true leaves,which could affect the photosynthesis and transpiration of the leaves,and the content of SiO₂ will decrease.In addition,it is also possible to reuse the silicon in the phytolith,which has been transferred from the first three true leaves to other growing plant organs.Moreover,the intensity of illumination on the true leaves of plants also affects the content of SiO₂ in the phytolith.?4?The morphological combination changes and elemental composition changes of phytoliths during leaf growth can provide theoretical basis and new understanding for the formation mechanism of phytoliths,Phytolith analysis for plant classification,archaeological or paleoenvironmental reconstruction.