Silicon uptake and utilization on Panicum maximum grass modifies C:N:P stoichiometry under warming and soil water deficit

Abstract

Future increases in air temperature are expected to increase the growth of Panicum maximum, but with climate change it will be common for the binomial increase in temperature and drought to occur. In this condition, plants may use strategies to adapt to this new scenario by favoring the uptake of beneficial elements such as Si and modifying plants nutritional status, but this needs to be tested. Thus, this research was conducted with the objective of evaluating the effect of warming and water restriction on Si uptake, accumulation, Si use efficiency, the C:Si, N:Si and P:Si stoichiometric ratios and their effects on growth of Panicum maximum plants grown under field conditions. The experiment was carried out in a 2 x 2 factorial scheme, with two temperature conditions (T): ambient temperature (aT), and high temperature (eT - increase of 2 degrees C above ambient temperature) combined with two levels of soil water availability (W), with water stress - non-irrigated (wS) and irrigated (sW), arranged in randomized blocks. Si concentration and accumulation are affected by temperature variations and soil water availability in different ways. Soil water restriction reduces leaf Si concentration, accumulation and increases the C, N and P stoichiometric ratios. Biomass production always improved for all growth cycles under warming and irrigated conditions, while, leaf C: Si, N: Si, and P: Si ratios decreased under non-irrigated and elevated temperature. It was revealed for the first time that the tolerance of Panicum maximum to warming and soil water restriction can be associated with Si uptake and changes in plant C:N:P stoichiometry.