SILICON

TLDR

Silicon is abundant in plants, often at levels comparable to macronutrients, yet it is generally omitted from culture solutions and considered nonessential, leading to silicon‑deprived plants that are structurally weaker, developmentally abnormal, and more susceptible to abiotic stresses, disease, and herbivory, mirroring the effects seen in silicon‑poor soils. The evidence overwhelmingly shows that silicon must be recognized as a major element influencing plant life.

Abstract

▪ Abstract Silicon is present in plants in amounts equivalent to those of such macronutrient elements as calcium, magnesium, and phosphorus, and in grasses often at higher levels than any other inorganic constituent. Yet except for certain algae, including prominently the diatoms, and the Equisetaceae (horsetails or scouring rushes), it is not considered an essential element for plants. As a result it is routinely omitted from formulations of culture solutions and considered a nonentity in much of plant physiological research. But silicon-deprived plants grown in conventional nutrient solutions to which silicon has not been added are in many ways experimental artifacts. They are often structurally weaker than silicon-replete plants, abnormal in growth, development, viability, and reproduction, more susceptible to such abiotic stresses as metal toxicities, and easier prey to disease organisms and to herbivores ranging from phytophagous insects to mammals. Many of these same conditions afflict plants in silicon-poor soils—and there are such. Taken together, the evidence is overwhelming that silicon should be included among the elements having a major bearing on plant life.