Differential response of growth and C:N:P stoichiometry to Si supply between bamboo and tree saplings

Abstract Background Silicon (Si), while not an essential element for plant growth, can be important for high Si-accumulating Poaceae, such as Moso bamboo. However, other trees do not actively take up dissolved silicic acid [Si(OH)4] from the soil, likely because they have fewer or no specific Si transporters in their roots. It is unclear what causes the different growth and nutrient status between bamboo and other trees under varying Si supply. Results In this study, we found that Si addition increased the biomass production of P. pubescens saplings, likely by improving its net photosynthetic rate and nutrient status, which contrasted to the saplings of P. bournei and S. superba. In addition, we found that C concentrations of aboveground tissues in P. pubescens declined with increasing Si supply, likely due to a partial substitution of organic C compounds by Si. Si addition increased the foliar C:N stoichiometry in the saplings of P. bournei and S. superba through altering their concentration of C and N, but did not affect the C:N or N:P stoichiometry of C. lanceolata and P. pubescens. Conclusions Si elicited either a positive or negative effect on plants, such as improve or weaken photosynthetic capacity, increase or decrease the concentration of C and N in plants, depending much on plant species and the Si supply level of in the environment. These results have implications for assessing the growth and nutrient status between bamboo and trees (i.e, high Si-accumulating plants compared to other plants) when Si availability is altered in ecosystems.