Résumé
Aims
Silicon (Si) has beneficial effects in a variety of plant species and environments. Soil and climate affect silica accumulation in given plant species, but their roles on foliar silicification patterns and balance between silica and C-rich biopolymers as structural components is poorly known.
Methods
We studied silica deposition
in situ
in sugarcane leaves collected in three tropical environments differing in soil and climate. Plant silica deposits were physically extracted from leaves through wet digestion. Leaves were observed and mapped for Si by ESEM-EDX. The C-rich biopolymers in leaves were determined by the Van Soest method.
Results
Silicon accumulation in the leaves was related to bioavailable Si in soil and plant transpiration. Epidermal silica deposits were either limited to silica cells as dumbbell-shaped phytoliths, or expanded to long and short cells arranged in prominent veins fully silicified, depending on whether the leaf Si concentration was lowest or highest. The size of silica deposits increased with increasing leaf Si through an increasing number of conjoined silicified cells. Leaf ash-free cellulose and Si concentrations were negatively correlated.
Conclusions
Soil and climate impact markedly the magnitude of foliar silicification, with possibly significant impact on mechanical properties and Si-related plant functions. Environmental conditions further impact the counterbalance between silica and cellulose as leaf structural components via different levels of Si accumulation.