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

Abstract AimsSilicon (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. To explore the influences of Si availability on the growth, photosynthesis, nutrient status and C:N:P stoichiometry of bamboo and other trees.MethodsWe used one-year seedlings of P. pubescens, P. bournei, S. superba and C. lanceolata in a pot experiment where three widely differing levels of silicon were supplied, and measured growth traits, photosynthetic gas exchange properties and C:N:P stoichiometry of seedling responses to three levels Si supply and analyzed the impacts of Si supply on growth and nutrient status of bamboo and tree saplings.ResultsWe found that Si increased the biomass production of P. pubescens seedlings with the higher concentration of Si supply, likely by improving its photosynthesis and nutrient status net photosynthetic rate, which contrasted to the seedlings 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. We also found that Si treatments increased the foliar C:N stoichiometry in the seedlings 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.ConclusionsSi 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 ambient supply level of Si in the environment. These results have implications for assessing the growth and nutrient status between bamboo and other trees (i.e, high Si-accumulating plants compared to other plants) when Si availability is altered in ecosystems, such as when Si availability in ecosystems is altered by bamboo expansion.