Nitrogen availability and plant-plant interactions drive leaf silicon concentration in wheat genotypes

Estimating plasticity of leaf silicon (Si) in response to abiotic and biotic factors underpins our comprehension of plant defences and stress resistance in natural and agroecosystems. However, how nitrogen (N) addition and intraspecific plant-plant interactions affect Si accumulation remains unclear. We grew 19 durum wheat genotypes (Triticum turgidum ssp. durum) in pots, either alone, or in intra- or intergenotypic cultures of two individuals, and with or without N. Aboveground biomass, plant height and leaf [Si] were quantified at the beginning of the flowering stage. Nitrogen addition decreased leaf [Si] for most genotypes, proportionally to the biomass increase. Si plasticity to plant-plant interactions varied significantly among genotypes, with both increases and decreases in leaf [Si] when mixed with a neighbour, regardless of the mixture type (intra-/intergenotype). Besides, increased leaf [Si] in response to plant-plant interactions was associated with increased plant height. O...