Abstract: A field experiment with randomized design was conducted to study the effects of six planting patterns of peanut, i.e., spring sowing and plastic film mulching, spring sowing and open cultivation, summer sowing and plastic film mulching, summer sowing and open cultivation, intercropped in wheat field, and control of intercropped in wheat field, on soil microbial biomass C, soil active microbial biomass, and soil respiration rate. The results showed that the growth stage and planting pattern of peanut had significant effects on soil microbial biomass and respiration rate. With the prolonged time after anthesis, soil microbial biomass C, active microbial biomass, and respiration rate increased gradually, peaked at pod-setting stage, and decreased then. Open cultivation enhanced soil microbial biomass C and respiration rate but reduced soil active microbial biomass, being unfavorable to soil nutrient transformation and nutrient availability, while plastic film mulching increased soil active microbial biomass, and consequently, promoted soil nutrient transformation and nutrient availability. Comparing with intercropped in wheat field and open cultivation, intercropped in wheat field and plastic film mulching increased soil microbial biomass C, active microbial biomass, and respiration rate, which immobilized more soil nutrients and was not conducive to peanut growth.

Key words: peanut, planting pattern, soil, microbial biomass C, active microbial biomass, Ca²⁺, salicylic acid, ROS, pathogenesis related protein.