Abstract: This article is focused on the relationship between the algae red tide, vitamin B₁ and B₁₂ in Dapeng Bay. Before red tide arising, the interrelationship between vitamin B₁ and Nocliluca scientillans is obvious. But it has no effect during the period of red tide. And after red tide, it is more obious than that between vitamin B₁ and Chattonella. The interrilationship between vitamin B₁₂ and Bonyaulax polygramma is much clearer than that between vitamin B₁ and Gonyaulax polygramma, during red tide.

Key words: muskmelon, increasing application of CO₂ to rhizosphere, photosynthetic characteristics, yield, quality.