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Can soil nitrate:ammonium ratios influence plant carbon:nitrogen ratios of the early succession plant? Can plant carbon:nitrogen ratios limit the plant growth in early succession? To address these two questions,we performed a two-factor (soil nitrate:ammonium ratio and plant density) randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate:ammonium ratios,the carbon:nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings.Under adequate nutrient status,both soil nitrate:ammonium ratios and plant density influenced the carbon:nitrogen ratios and growth rate of A.sphaerocephala seedlings.Under the lower soil nitrate:ammonium ratios,with the increase of soil nitrate:ammonium ratios,the growth rates of plantheight and shoot biomass of A.sphaerocephala seedlings decreased significantly; with the increase of plant carbon:nitrogen ratios,the growth rates of shoot biomass of A.sphaerocephala seedlings decreased significantly.Soil nitrate:ammonium ratios affected the carbon:nitrogen ratios of A.sphaerocephala seedlings by plant nitrogen but not by plant carbon.Thus,soil nitrate:ammonium ratios influenced the carbon:nitrogen ratios of A.sphaerocephala seedlings,and hence influenced its growth rates.Our results suggest that under adequate nutrient environment,soil nitrate:ammonium ratios can be a limiting factor for the growth of the early succession plant.