Abstract:

In this study，the seedlings of Malus × domesica ‘Hanfu’/M. baccata were planted on a typical low-carbon sandy soil in the apple orchard of Liaoning Province. Glucose which is one of the final products of decomposition of various organic substances and is easily absorbed and utilized is used as a carbon source. The method of adding glucose and soil sterilization treatment is designed to study the effect of exogenous carbon on the components of soil active organic carbon pool in apple root zone and plant growth and development. The results showed that adding glucose and adding glucose treatment after sterilization can significantly increase the content of low-carbon sandy soil organic carbon，microbial biomass carbon，water-soluble organic carbon and particulate organic carbon while the soil sterilization treatment alone reduced the soil organic carbon，microbial biomass carbon and particulate organic carbon content. Adding glucose and adding glucose after sterilization treatments significantly increased the soil cellulase and β-glucosidase activity. And adding glucose and adding glucose after sterilization treatments increase the key enzymes involved in respiratory metabolism pathways，phosphoenolpyruvate carboxylase（PEPC），isoforms citrate dehydrogenase（IDH）and malate dehydrogenase（MDH）activities. Adding glucose and adding glucose after sterilization treatments enhance apple plant photosynthesis，promote biomass accumulation and plant growth. In summary，adding five times the amount of easily decomposable carbon source to low-carbon sandy soil according to the soil microbial background level can significantly increase soil organic carbon content and active organic carbon pool components，increase soil enzyme activity and the key enzymes involved in respiration metabolism activities，enhance the photosynthetic capacity of plants，and promote plant growth and development.

Key words: apple, glucose, soil sterilization, root zone, soil active organic carbon pool, respiratory metabolism, growth and development