Studies On Allelopathy Of Invasive Smooth Cordgrass (Spartina Alterniflora Loisel.) On Skeletonema Costatum

In this study, exotic Spartina alterniflora in Jiuduansha islands and red tide algae Skeletonema costatum were researched. Through the growth of Skeletonema costatum cultured experiment, Analysis of allelochemicals of Spartina alterniflora, exploring the effect from allelochemicals on Skeletonema costatum growth. And these results can provide scientific gist for the use of Spartina alterniflora allelopathic diffusion control dispersal redtide causive alga.In this study, living plants and litters of Spartina alterniflora and soil samples were collected and taken back to our library. Different concentrations of water extracts and different tissues of Spartina alterniflora were used to conduct Skeletonema costatum cultivation experiment, inquiry of Spartina alterniflora on the allelopathic effect; Determination of contained allelopathic Species Spartina alterniflora and explore different effects of substances on the growth of Skeletonema costatum, the final design of the orthogonal experiment under the condition of different factors, obtained the optimal levels of each factor. The results are as follows:(1) Allelopathy is existed between Spartina alterniflora and Skeletonema costatum. Straw aqueous extracts could inhibit the growth of Skeletonema costatum, and this inhibitory effect enhanced with the increase of straw aqueous extracts concentration; straw aqueous extracts changed cells of Skeletonema costatum in chlorophyll content, SOD, POD activity and MDA content, the chlorophyll content, the activity of SOD and pod reduced and MDA content increased.(2) The inhibitory effect of different straw extracts different soaking time on Skeletonema costatum. When the soaking time was 2d and 5d, the inhibitory effect of the extract on the algae was not significantly different, but the inhibition rate decreased significantly when the soaking time was 10d;(3) Extracts of different tissues from Spartina alterniflora on the growth of Skeletonema costatum showed that low concentration(≤0.02 g?mL-1) promotion and high concentration(≥0.04 g?m L-1) inhibition; mutual flower meters from the root, stem, leaf and nutrient solution at high concentration(0.1g?m L-1) of Skeletonema costatum inhibition strength stem > leaf > root > stem > nutrient solution;(4) Allelopathic substances of extracts of different tissues from Spartina alterniflora mainly for long chain fatty acid, palmitic acid, oleic acid and phthalic acid; and the three substances of Skeletonema costatum growth showrs low concentration(≤1 μmol/L) promotion and high concentration(≥15 μmol/L)inhibition. The inhibition enhanced with the increase of soil water extract concentration; oleic acid, palmitic acid, phthalic acid of Skeletonema costatum growth inhibition effect in the same concentration showed oleic acid > palmitic acid > phthalic acid;(5) Palmitic acid, oleic acid and phthalic acid by several times could achieve low dose levels of skeletonema costatum growth inhibition and the inhibition effect is higher than that of the one shot dosa experimental group;(6) The impact extent of kinds of allelochemicals, dosing frequency and light intensity on the inhibition of Skeletonema costatum shows kinds of allelochemicals > dosing frequency > intensity of illumination; in the design of orthogonal experiment group, the optimum level of every factor of allelochemicals oleic acid, dosing frequency of 5 times, light illumination for 3000 lx.