Genetic diversity and structure of 15 populations of Phragmites australis growing in the Yellow River Delta and wetlands nearby were investigated using starch gel electrophoresis. Analysis based on 17 enzyme loci coding for 8 enzyme systems showed that there exists a high level of genetic variability in P. australis. The proportion of polymorphic loci is 49.0%, the average number of alleles per locus is 1.53, and the average expected heterozygosity is 0.221. The genetic diversity was found within populations rather than among populations (GST=0.226). A high level of clonal diversity was indicated in this species with PD (proportion distinguishable variations, PD=0.53). The size of different clones, however, varied significantly. The clonal structure analysis demonstrated a clear genetic mosaic. There is a negative correlation between salinity and growth rate of the reeds. Genetic distances were positively correlated to the geographical distances among populations of P. australis. The populations in saline habitats have become differentiated from their freshwater counterparts.

FDR（Frequency Domain Reflectometry） 频域反射仪是一种用于测量土壤水分的仪器，它利用电磁脉冲原理、根据电磁波在介质中传播频率来测量土壤的表现介电常数（ε），从而得天土壤容积含水量（θv）。介绍了FDR系统的测量原理、系统安装、测量方法及其在土壤水分连续动态监测中的应用，并对实际测量结果进行了校正，可以作为FDR校正的参考。在半干旱区皇甫川流域的应用实践表明，FDR具有简便安全、快速准确、定点连续、自动化、宽量程、少标定等优点，是一种值得推荐的土壤水分测定仪器。