Abstract: By the method of intraperitoneal injection, this paper studied the dynamic distribution of microcystin-LR (MC-LR) in the muscle, liver, serum, gallbladder, gill, and intestine of tilapia (Oreochromis niloticus). During the experiment, MC-LR was detected in the liver, serum, gallbladder, gill, and intestine, but not detected in the muscle. A distinct difference was observed in the MC-LR residues in different tissues or organs. The MC-LR residue was the highest (0.902-4.938 mg·kg^-1) in liver, and was in the range of undetected  to 0.390 mg·L^-1 in serum, undetected  to 0.236 mg·kg^-1 in gallbladder, 0.0134-0.0369 mg·kg^-1 in gill, and 0.007-0.016 mg·kg^-1 in intestine, respectively. At 84 h after injection, the MC-LR residue in the liver, gill, serum, and gallbladder decreased significantly, and no MC-LR was detected in serum and gallbladder, which meant that O. niloticus had very strong detoxic ability on MC-LR. The MC-LR concentration in the liver and gallbladder had a sharp decrease at 36 h after injection, suggesting that liver and
 gallbladder could be the main detoxic organs of MC-LR. No MC-LR was detected in the muscle during the experiment, which meant that MC-LR could not be accumulated in muscle when O. niloticus was injected with low dosage MC-LR.

Key words: Winter wheat, Photosynthesis, Transpiration, Water use efficiency