Experiment of Kandelia obovata Seedlings in Different Estuaries in Zhejiang

In May and June 2019, 1-year container seedlings and hypocotyl of Kandelia obovata which were from Quanzhou city, Fujian Province and Longgang city, Zhejiang Province were planted on estuaries of the Qiantang River in Ningbo, Jiaojiang River in Taizhou and Oujiang River in Wenzhou. In April 2020, the seedling growth and soil chemical properties were investigated, and the differences of growth indexes, leaf parameters and biomass of K.obovata seedlings were analyzed.. The results showed that the content of soil salt, organic matter, hydrolyzed nitrogen, available phosphorus and available potassium in the Oujiang river estuary had significantly difference with that in the Qiantang river estuary and Jiaojiang river estuary, but K. obovata could grow well in tested estuaries. In the three experimental sites, the preservation rate of K.obovata germplasm from Longgang was significantly higher than that from Quanzhou K.obovata germplasm (P<0.05). The preservation rate of container seedlings and hypocotyl of Longgang germplasm in the Qiantang river estuary was 72.92% and 82.78%, respectively, while that of Quanzhou was only 33.47% and 15.28%. The branching number of container seedlings of Longgang germplasm was significantly higher than that of Quanzhou germplasm in the Qiantang river estuary , but the height growth of hypocotyl seedlings was the opposite. Compared with Quanzhou germplasm, container seedlings of the Longgang exhibit higher increases in leaf number and leaf area in the three experimental sites, the hypocotyl seedlings were reverse. The leaf length and leaf width of the Quanzhou germplasmwere the largest in the Oujiang River, and the smallest in the Jiaojiang River, while the Longgang germplasm had no significant difference in the three experimental sites. The sequence of root, stem, leaf dry weight and bioaccumulation of K. obovata from high to low was: Oujiang River >Qiantang River >Jiaojiang River. The biomass indexes of K. obovata container seedlings from Longgang were all higher than those from Quanzhou germplasm, but the hypocotyl seedlings were the opposite. Therefore, the container seedlings of Longgang K.obovata germplasm should be selected for mangrove construction in Ningbo and Taizhou estuarine tidal flat, while hypocotyl seedlings of K.obovata germplasm are preferred in Wenzhou.