Abstract: To reveal the responses of seed germination of C. korshinskii Kom. to light intensity and sand burial depth, an experiment was conducted to investigate the characteristics of seed germination of C. korshinskii under different light intensities (55.4% natural sunlight (NS), 18.9% NS, 5.5% NS, and 2.2% NS) and sand burial depths (0.0, 0.5 1.0, 2.0, and 4.5 cm) in a greenhouse. The results showed that light intensity had significant effects on germination percentage (GP), germination rate (GR), germination index (GI), and vigor index (VI) of C. korshinskii seeds while sand burial depth had significant impacts on GI and VI. Significant interactive effects of light intensity and sand burial depth on GP, GI and VI were also observed. The GP, GR, and GI of C. korshinskii seeds decreased with the decline of light intensity at all burial depths except 0 cm. With the decreasing light intensity, VI showed an increasing trend at 0 cm sand burial depth, while it continually or undulately decreased at other depths. Under the light intensities of 55.4% NS, 18.9% NS, and 5.5% NS, the maximums of GP were detected at the depth of 1.0 cm sand burial (45.0%, 30.6%, and 27.5% respectively) and the minimums were observed at 0 cm sand burial depth (22.2%, 22.1%, and 20.0% respectively). GR, GI, and VI all increased and then decreased with increasing sand burial depth, all of which maximized at 0.5-2.0 cm sand burial depth. Under 2.2% NS, all germination parameters decreased with increasing sand burial depth. At 1.0, 2.0, and 4.5 cm sand burial depths, GP, GR and GI were significantly lower than that at 0 cm sand burial depth (P<0.05). The differences in VI between 0 cm and other sand burial depths were significant (P<0.05). In summary, both light intensity and sand burial depth were important factors driving the germination of C. korshinskii seeds. Sand burial could strengthen the dependence of seed germination on light. Seed germination could be facilitated by moderate depths of sand burial under high light intensity but be restrained by sand burial under low light intensity.

Key words: pesticide, research progress, paddy field, rice water quality model