Early Growth Characterization and C:N:P Stoichiometry in Firmiana simplex Seedlings in Response to Shade and Soil Types

Abstract

Light and soil environments have extensive heterogeneity for many plants species affecting plant growth, reproduction, and distribution. However, the interaction effects of these two factors on the ecophysiological traits and adaptive strategy of plants remain largely unclear. In the present study, we set four shading levels and three soil types to investigate the effects of shade and soil type on seedlings growth, C:N:P stoichiometry responses, and nutrient use efficiency in Firmiana simplex (F. simplex). The maximum of total biomass was observed in acid purple soil under 75% shade, with a maximum difference of 3.6 times. With the increase in shading intensity, C content in the root, stem, and leaf reached maximum value under 75% shade. However, C content in the root and N content in the stem reached a maximum value of 420.6 g·kg−1 and 13.7 g·kg−1 in acid purple soil, respectively. With the increase in shading intensity, the total C and N accumulation showed a trend of progressive increase and then decrease, reaching the maximum value of 346.2 mg and 10.7 mg under 75% shade, respectively. The N:P ratios of various organ ranged from 3.1 to 11.9 in acid purple soil and red soil, indicating that the seedlings growth was restricted by nitrogen. We concluded that the interactions of shade and soil types might adjust the C:N:P stoichiometry and influence the dynamic balance between nutrients and organs in F. simplex seedlings.