Abstract: To understand the effects of different acclimation temperature on the thermal tolerance of juvenile Silurus meridionalis Chen, the juveniles with a mass of 16.9±0.3 g were acclimated at water temperature 10 ℃, 20 ℃ and 30 ℃ for 2weeks, and their thermal tolerance under a temperature variation rate of 1℃·h^-1 was evaluated. The results showed that the critical thermal maximum (CT_max), lethal thermal maximum (LT_max), critical thermal minimum (CT_min), and lethal thermal minimum (LT_min) at acclimation temperatures 10 ℃, 20 ℃ and 30 ℃ were 34.13 ℃, 38.22 ℃ and 39.41℃, 34.84 ℃, 38.63 ℃ and 39.53℃, 4.88 ℃, 5.90 ℃ and 9.80 ℃, and 4.12 ℃, 5.03 ℃ and 8.29 ℃, respectively,i.e., the test parameters all increased with increasing acclimation temperature. The thermal tolerance amplitude at 10 ℃, 20 ℃ and 30 ℃ was 29.25 ℃, 32.32 ℃ and 29.61 ℃, respectively. Within the range of acclimation temperature 10 ℃-20 ℃, the acclimation response ratio (ARR) at high and low temperatures was 0.41 and 0.12;while within the range of acclimation temperature 20 ℃-30 ℃ , the ARR was 0.10 and 0.39. The thermal tolerance polygon area of the juveniles within the range of acclimation temperature 10 ℃-30 ℃ was calculated as 617.5 ℃². It was indicated that the thermal tolerance of S. meridionalis was dependent on acclimation temperature.

Key words: Pasture-crop rotation, Medicago sativa, Soil nitrogen, Soil phosphorus, Soil organic matter, Rotation pattern