Abstract: With two cucumber varieties (greenhouse variety Jinyou No. 1 and open-field variety Jinyan No. 4) as test materials, this paper measured their net photosynthesis rate (P_n) under given environmental conditions including CO₂ concentration, temperature and illumination intensity in phytotron, and the responses of P_n (y) to these factors were modeled by mathematic methods, which could be described as y=exp(-242.1217/x₁)［61.0202-0.11(x₂-30.926)²］exp(-272.8874/x₃)+0.9355 for Jinyou No. 1, and y=exp(-179.8803/x₁)［50.0771-0.0609(x₂-34.3455)²］exp(-267.9653/x₃)+0.7377 for Jinyan No. 4, where x₁, x₂ and x₃ represented the values of CO₂ concentration, temperature, and illumination intensity, respectively. The response of P_n to temperature accorded with conic function, while its responses to CO₂ concentration and illumination intensity accorded with exponential function.

Key words: seasonal dynamics, soil physicochemical properties., soil microbial biomass carbon and nitrogen, soil layer, forest conversion