Abstract:

In order to investigate the stress response of root morphology and nutrient loading of Clematis fruticose mycorrhizal seedlings to nitrogen deposition， 1-year-old C. fruticose mycorrhizal and non-mycorrhizal seedlings（-M） were used as materials. The inoculation treatments included single-inoculation（Rhizophagus intraradices， +R； Funneliformis mosseae， +F）， mixed-inoculation（AMF agents 1∶1 mixture， +RF）. Four nitrogen deposition treatment were set， including no nitrogen（CK， 0 g·m^-2·a^-1）， low nitrogen（LN， 3 g·m^-2·a^-1）， medium nitrogen（MN， 6 g·m^-2·a^-1）， high nitrogen（HN， 9 g·m^-2·a^-1）. The fine root morphology with diameter of ≤0.5 mm（including total root length， total surface area， total volume and tips）， mycorrhizal colonization rate， soil spore density and all parts nutrient loading of a plant（including carbon， nitrogen and phosphorus content） were determined under inoculation and nitrogen deposition treatments. The results indicated that： ①Under +R and +RF treatments， the seedlings mycorrhizal colonization rate and soil spore density were the maximum in LN treatment， and the mycorrhizal colonization rate in LN treatment was significantly higher than that in HN treatment. Under +F treatment， the mycorrhizal colonization rate was no significant difference between the different nitrogen deposition treatments. ②Under 0N treatment， the fine root morphology with diameter of ≤0.5 mm in +F and +R treatments， including total root length， total surface area， total volume and tips， were higher than that in -M treatment respectively. However， the above root morphological indicators of C. fruticose seedlings were decreased with the increase of nitrogen deposition under +F and +R treatment. ③Under +F and +R treatments， the nutrient loading of seedlings increased with the increasing of nitrogen deposition content. The carbon， nitrogen and phosphorus（C，N and P） contents of mycorrhizal seedlings were significantly higher than that of non-mycorrhizal seedlings， and the seedlings C， N and P contents were the maximum under +F treatment. ④There was a positive correlation between fine root morphology with diameter of ≤0.5 mm and nutrient content of seedlings. Thus， inoculation treatment changed the response of fine root morphology of C. fruticose seedlings to nitrogen deposition. The F. mosseae effectively enhanced the seedlings adaptability to nitrogen deposition， and that improved the seedling nutrient loading under high nitrogen deposition.

Key words: Clematis fruticosa, arbuscular mycorrhizal fungi, nitrogen deposition, fine root morphology, nutrient loading