title: Effects of arbuscular mycorrhizal fungi on the growth, photosynthesis and photosynthetic pigments of Leymus chinensis seedlings under salt-alkali stress and nitrogen deposition.
abstract: Leymus chinensis is the most promising grass species for salt-alkaline grassland restoration in northern China. However, little information exists concerning the role of arbuscular mycorrhizal (AM) symbiosis in the adaptation of seedlings to salt-alkali stress, particularly under increased nitrogen deposition, which has become a major environmental problem throughout the world. In this study, Leymus chinensis seedlings were cultivated in soil with 0, 100 and 200mM NaCl/NaHCO3under two forms of nitrogen (10mM NH4NO3or NH4Cl: NH4NO3=3:1), and the root colonization, growth and photosynthetic characteristics of the seedlings were measured. The results showed that the colonization rate and intensity decreased with increasing salt-alkali stress and were much lower under alkali stress. The nitrogen treatments also decreased the colonization, particularly under the NH4+-N treatment. Compared with the non-mycorrhizal controls, mycorrhizal seedlings generally presented higher plant biomass, photosynthetic parameters and contents of photosynthetic pigments under stresses, and the inhibitive effects of alkali stress were substantially stronger. In addition, both nitrogen forms decreased the physiological indexes compared with those of the AM seedlings. Our results suggest that salt stress and alkali stress are significantly different and that the salt-alkali tolerance of Leymus chinensis seedlings could be enhanced by associations with arbuscular mycorrhizal fungi, in which would yield better plant growth and photosynthesis. Excessive nitrogen in the soil affects mycorrhizal colonization and thereby inhibits the growth and photosynthetic ability of the seedlings.
authors: Alkali Soil Natural Environmental Science Center, Northeast Forestry University/Key Laboratory of Saline-alkali Vegetation Ecology Restoration in Oil Field, Ministry of Education, Harbin 150040, China; Key Laboratory of Vegetation Ecology of Ministry of Education, Institute of Grassland Science, Northeast Normal University, Changchun 130024, China.
authors: Jixiang
authors: J
authors: Lin
authors: Alkali Soil Natural Environmental Science Center, Northeast Forestry University/Key Laboratory of Saline-alkali Vegetation Ecology Restoration in Oil Field, Ministry of Education, Harbin 150040, China.
authors: Yingnan
authors: Y
authors: Wang
authors: Colleges of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.
authors: Shengnan
authors: S
authors: Sun
authors: Key Laboratory of Vegetation Ecology of Ministry of Education, Institute of Grassland Science, Northeast Normal University, Changchun 130024, China.
authors: Chunsheng
authors: C
authors: Mu
authors: Alkali Soil Natural Environmental Science Center, Northeast Forestry University/Key Laboratory of Saline-alkali Vegetation Ecology Restoration in Oil Field, Ministry of Education, Harbin 150040, China. Electronic address: xfyan@nefu.edu.cn.
authors: Xiufeng
authors: X
authors: Yan
mesh_terms: D000468:Alkalies; D002681:China; D038821:Mycorrhizae; D009584:Nitrogen; D010788:Photosynthesis; D018517:Plant Roots / Q000382:microbiology; D006109:Poaceae / Q000254:growth & development* / Q000382:microbiology; D012492:Salts; D036226:Seedlings / Q000254:growth & development / Q000382:microbiology; D013312:Stress, Physiological
chemical_list: D000468:Alkalies; D012492:Salts; D009584:Nitrogen
keywords: Arbuscular mycorrhizal; Leymus chinensis; Nitrogen deposition; Photosynthesis; Salt-alkali stress