| To investigate the effects of nitrogen reduction combined with application of arbuscular mycorrhizal fungi(AMF) on the growth characteristics, photosynthetic physiology, nitrogen metabolism process, and yield of wheat during the grain-filling stage under water-saving irrigation, a wheat line Landa 211 was used as the experimental material. Two irrigation amounts(normal irrigation of 400 mm, water-saving irrigation of 280 mm) and three nitrogen application levels［conventional nitrogen application(250 kg·hm-2), reduced 20% nitrogen fertilizer application(200 kg·hm-2), and reduced 40% nitrogen fertilizer application(150 kg·hm-2)］ were set up, inoculated with the AMF strain Funneliformes mosesae（FM） and no inoculation. The results indicated that FM could infect wheat roots and formed a stable symbiotic relationship. Compared with normal irrigation, the mycorrhizal infection rate, arbuscular growth rate, number of invasion points, and number of vesicles of FM decreased under water-saving irrigation. Compared with the conventional nitrogen application treatment under normal irrigation, reduced 20% nitrogen under water-saving irrigation and inoculation with FM treatment had no significant effect on the dry matter accumulation and leaf area of wheat population, but the plant height and total stem number of the population decreased. The chlorophyll content, chlorophyll fluorescence parameters, and gas exchange parameters of wheat showed no significant differences compared to the conventional nitrogen application treatment under normal irrigation, but were significantly higher than reduced 40% nitrogen treatments under water-saving irrigation and FM inoculation. Compared with the conventional nitrogen application treatment under normal irrigation, there was no significant difference in the total nitrogen content, free amino acid content, soluble protein content of wheat flag leaves, and the activities of nitrate reductase, glutamine synthase, glutamic pyruvate transaminase, and glutamic acid synthase under reduced 20% nitrogen with water-saving irrigation and FM inoculation. The wheat yield under water-saving irrigation and reduced 20% nitrogen combined with FM treatment reached 7 786.0 kg·hm-2, which was not significantly different from the yield under normal irrigation with conventional nitrogen application. To conclude, reduced 20% nitrogen and applying FM in combination with water-saving irrigation could maintain the chlorophyll content and photosynthesis of wheat during the grain-filling period, and maintain the activity of wheat nitrogen metabolism enzymes and metabolite content, which was a green water and fertilizer management model for water-saving, fertilizer saving, and high-yield maintenance in arid irrigation areas. |
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