Phenolic acids in plant root exudates have stronger allelopathic activity

but fewer researches are focus on this area of mangrove plants

especially the status in situ-conditions. In this work

the roots

rhizosphere soil and non rhizosphere soil of six plants in Guangdong Zhanjiang National Nature Reserve of mangrove were sampled in situ. The total content of phenolic acids was measured using a potassium ferricyanide-ferric chloride colorimetric method. The results indicated that the content in roots was the highest in Rhizophora stylosa

the average value was 8 837.28 μg/g. The content of phenolic acids in rhizosphere soil and non rhizosphere soil were the highest in Bruguiera gymnorrhiza

the mean value were 13.20 μg/g and 20.12 μg/g

respectively. In total 18 samples

only 8 samples of the content in rhizosphere soils were higher than that of non rhizosphere soil. The content of phenolic acid in rhizosphere soil may be lower than that in non rhizosphere soil due to the comprehensive effect of microbial decomposition or soil adsorption and degradation. The release percent of phenolic acid from mangrove root was very low

only 0.050 4% in Rhizophora stylosa. These results are important meaning for clarifing the mangrove ecological mechanism especially the mechanism of root microecology.