Abstract:

In this paper, the level and pattern of morphological variation of Phragmites australis in the Yellow River downstream wetland has been studied when water and salinity were considered as dominant ecological factors. A total of 14 populations from estuary to inland along the Yellow River and one freshwater population from Nanyang Lake were selected for study. The basal diameter, height, leaf length and width in the middle of stem, internode length in the middle of stem, internode amounts and panicle length of 30 plants from every population were recorded and analyzed. Results showed that the decreasing arrangement of CV (Coefficient of variation) within population of 7 morphological characters was from internode length in the middle of stem(0.2846), leaf width in the middle of stem (0.2536), panicle length (0.2449), leaf length in the middle of stem (0.2085), basal diameter (0.1875), internode amounts (0.1763) to height (0.1657). The variability of 7 morphological characters among populations was arranged decreasingly from height, leaf length in the middle of stem, internode length in the middle of stem, leaf width in the middle of stem, basal diameter, internode amounts to panicle length. Distinct morphological differentiation was observed mainly among BZH population, freshwater populations and saltwater populations, and all 7 morphological characters were significantly correlated with the combined factors of water and salinity. According to the pattern of morphological differentiation, the P. australis populations in investigated area could be divided into three ecotypes, including saltwater reed, freshwater reed and giant reed.