Effects of Nitrogen Fertilizer Application and Root Partition on the Photosynthetic Physiological Characteristics of Eucalyptus urophylla × Eucalyptus grandis and Dallergia odorifera Seedling

Eucalyptus urophylla × Eucalyptus grandis and Dalbergia odorifera were selected as the materials, pot experiment of E. urophylla × E. grandis and D. odorifera intercrop with 3 root partition and 3 nitrogen levels were carried out in the greenhouse. Dry matter and the photosynthetic characteristics were analyzed to study the effects of different planting patterns and nitrogen application levels on physiological metabolism in E. urophylla × E. grandis and D. odorifera. The results show that different nitrogen levels and root partition alter physiological and growth characteristics of E. urophylla × E. grandis and D. odorifera. Nitrogen application significantly increases dry matter accumulation, leaf area index, chlorophyll content, soluble carbohydrate, protective enzyme activity, light energy utilization efficiency and photosynthetic characteristics of E. urophylla × E. grandis and D. odorifera. But the influence caused by root partition are different between E. urophylla × E. grandis and D. odorifera. In the non-separated mode, the dry matter accumulation of E. urophylla × E. grandis seedlings without nitrogen, low nitrogen and high nitrogen levels is 8.74%, 6.97%, 5.49%, 16.43%, 24.18%, 15.32%, respectively. D. odorifera is the best membrane separation effect. Under 3 nitrogen application levels, the dry matter accumulation is higher than 32.70%, 30.82%, 38.75%, 11.26%, 15.39%, 4.25%. The competitive ability of E. urophylla × E. grandis is stronger than D. odorifera in different root partition models. The physiological metabolism and photosynthesis of E. urophylla × E. grandis seedlings in no barrier mode are the highest, followed by mesh barrier and solid barrier, but solid barrier is the best mode in D. odorifera, and the no berrier was better than the mesh barrier. Therefore, the mixed model with E. urophylla × E. grandis is used to increase the growth of plants by increasing physiological metabolism and promoting photosynthesis of plants.