Effect of Root Interaction of Chestnut-leaved Oak and Persian Maple in Pure and Mixed planting on spatial Variability of Urease Enzymes Exudation

Background and objective: Root interaction is the most important factor that influence on enzymes exudations of plant roots in rhizosphere, that depending on composition, species type and soil depth have different spatial distribution. Nowadays restricted researches had been done about relation of rhizosphere processes with soil rhizosphere or even identity of space importance of rhizosphere processes in different species. Tree species regarding to root morphology and physiology as well as nutrients needs have different rhizosphere. The aim of this research is to assay spatial variability of urease enzymes exudation on rhizosphere of Chestnut-leaved Oak and Persian Maple in pure and mixed planting.
Material and methods: To get the research goal, 18 modern rhizotrons were made and applied. 12 Raster-Access-Ports placed in each rhizotron to get root exudates. These ports were in distinct depths and distances for calculating special variability of root enzymes exudations. Related to space of ports of rhizotrons, two lower depths (50 and 75 cm) were full with soil and two upper depths with soil and litter (4% of weigth). One years old seedlings of Quercus castaneifolia and Acer velutinum were planted in four treatments of species composition including pure, mixed and control (without planting seedling). Soil sampling was done 6 months after planting in different soil depth of rhizotrons and ureaseactivity was determined by Kandeler method. Enzyme efficiency was calculated by subscripted enzyme activity in each place from corresponding amount of control (without root) and don't show catalytic efficiency.
Results: The results showed that urease exudation contents were significantly differences in planting composition (p < 0.05) while the most amount of enzyme exudation revealed in the pure Oak and mixed planting and the lowest was in control. Spatial variability of urease activity only showed significant difference on mixed planting treatment (p<0.05). However spatial variability of enzyme efficiency was significant on pure maple and mixed planting treatments (p<0.05). Urease exudation wasn't significant in different distances from collar seedlings with exception urease efficiency in pure oak planting treatment (p<0.05).
Conclusion: Results suggested planting seedlings and species composition have greater impact on urease exudation than soil depth during research periode. Compare the results with other studies have uncertainty revealed in spatial variability of urease exudations in rhizosphere perhapse was related to rooting system. Each species has its own rhizosphere zones based on their rooting structure and in any kind of species composition competition will be different because the rooting structure.