Plant Nutrition, Stress and the Forgotten Element, Silicon
Stress is a universal condition that plants are exposed to. Stressful features are either biotic, such as diseases and pests, or abiotic, such as gravity and elemental shortages and excesses. One important method to study these and other conditions is solution culture, which is the only one to permit close monitoring and control of the medium. Before the advent of this method that could not be done, but once developed in the mid-1800s, it led to the determination of the essential elements, or nutrients. Silicon, the investigators concluded, was not one of them, and omission of silicon from the formulation of nutrient solutions has been routine ever since. In the real world, however, the world of the field, there are no minus-silicon plants. Plants grown in conventional nutrient solutions are therefore experimental artifacts. Silicon is the second most abundant element in rocks and soils, and the concentration of silicon in the soil solution exceeds that of phosphate by factors of 100 -1000. Most plans contain the element at(dry weight basis) values of no less than 0.1%, and many, such as rice, wheat and sugarcane, have more silicon than any other mineral element. Evidence will be presented that silicon often affords crops protection from commonly encountered stressful conditions. It is urged that silicon be included in the formulation of nutrient solutions.