Seasonal Variations of Absolute and Specific Acid Phosphatase Activities on Rhizosphere Competition in Pure and Mixed Planting of Chestnut-Leaved Oak and Persian Maple

Rhizospheric competition play a vital role in plant nutrition such as phosphorus availability. Inter and intraspecific competition have the maximum influence on rhizosphere function. It can be expected that rhizosphere exudations (such as acid phosphatase) will change in the various competitive scenarios, considering the specific rhizosphere characteristics of plant species. Acid phosphatase (AP) is one of the most important rhizospheric enzymes and it is a specific enzyme to the phosphorus cycle. This investigation was carried out to study the absolute and specific AP activities on rhizosphere competition in pure and mixed planting of Quercus castaneifolia and Acer velutinium (two important species of forests of northern Iran) during different seasons by a novel rhizotron. Sampling was done within 18 rhizotron access tube (3 composition treatments/5 replications with 3 controls rhizotron without seedling) in 4 seasons, then absolute and specific AP activities were determined. Results revealed that there were significant differences between the absolute and the specific AP activities of different planting compositions and seasons (P<0.05). Mixed planting had the most absolute AP activities (2370.37±154.16µgPNPg-1h-1) in autumn while control treatment had the least absolute AP activities (991.75±108.65µgPNPg-1h-1) in summer. Amounts of absolute and specific AP activities showed significant decrease at the end of experiment compared with the beginning of study times. Results showed Quercus castaneifolia and Acer velutinium companion planting had better rhizosphere structure, physiology and morphology and also showed that mixed planting have better root growth, so we concluded that this treatment provide more phosphorus during different seasons.