Abstract: Based on the monitoring data of Dishui Lake from September 2011 to August 2012, this paper analyzed the spatiotemporal distribution of chlorophyll-a (Chl-a) and its correlations with the main aquatic ecological factors in the Lake. There was an obvious temporal variation of the Chl-a concentration, with two peaks in March and July, respectively. Spatially, the Chl-a concentration also had definite differentiation, being generally higher in the lake center than at the other points. Absolute principal component score analysis and multivariate liner regression (APCSMLR) were adopted to approach the relationships between the Chl-a concentration and the water quality variables, which showed that the latent water quality variables F₁ and F₂ had greater correlations with the Chl-a concentration, and a correlation model of the latent variables and Chl-a concentration was established. The Chl-a concentration had close relationships with the water temperature, dissolved oxygen, total dissolved phosphorus, and available phosphorus, and phosphorus was the limiting factor of the primary productivity of Dishui Lake. It was suggested that the phosphorus concentration in the water could be the main factor controlling the eutrophication of Dishui Lake.

Key words: Trichoderma spp., root-knot nematode, control effect, rhizosphere colonization.