Biogeochemical effect of karst soil on the element contents in the leaves of two species of Flos Lonicerae

Abstract

In order to study the characteristics of element values in the cell of plants and soils and their relationships that would help to evaluate the biogeochemical effect of soil on the element contents in the cells of plants in the same environment of Southwestern China, the soil samples were collected for analysis and the weight and atom percentage of elements (WT% and AT%) in the leaves of two different species of <I>Flos Lonicerae</I> were analyzed by the electron probe (EDX-9100). The results of soil analysis show that the nutrient element contents in the soil are determined by the liable content of elements, which were arranged as: Ca > Mg > Cu > Mn > K > Na > P > B > SiO<sub>2</sub> > Zn > Fe, even though the total element values in soil of different horizons were arranged as: SiO<sub>2</sub> > Fe > Ca > Mg > K > Na > Mn > P > Zn > B > Cu. It indicates that karst environment is composed of soluble calcium-rich rock and soil scarcity. Moreover, the migratory velocity and availability of elements are also determined by their coefficient variability. According to statistical results, Ca, Mn and P in the soil have high coefficient variability, reflecting its background of karst soil. Based on the electron probe, it is shown that the content of Ca is higher while Mg is the lowest in the cell of two different species of <I>Flos Lonicerae (r</I> = –0.156, <I>P</I> < 0.05) and the content of P in the cell is inferior to Ca (<I></I>r = 0.868, <I>P</I> < 0.01). By studying the relationship of soil and the plants, it can be seen that these results are probably caused by the characteristics of local biogeochemistry. Ca is mainly absorbed by plant with the help of transpiration and accumulated in the cell, and thus becomes a predominant element in the cell. The accumulation of Ca in cell of plant will affect the absorbency and the content of other elements in the cell of <I>Flos Lonicerae</I>, resulting in the different contents of other elements in the <I>Flos Lonicerae</I> through synergistic and antagonistic action, followed by the affected quality and officinal value of the <I>Flos Lonicerae</I>.