However, certain disorders produce acute stunting of growing points or young leaves, resulting in characteristic growth patterns. Deficiencies of boron, calcium, potassium, and sometimes zinc can kill growing points, and in woody plants especially, this can lead to dieback of the shoot. Root stunting is characteristic of calcium deficiency, acidity, aluminum toxicity, and copper toxicity. Some species may also show it when boron deficient. An interaction occurs when two factors modify each other's effect.
Interactions are common in plant nutrition.
A consequence is that what holds for one plant or culture formulation or environment does not always hold for another set of conditions. Many interactions that occur in soil or at the soil-root interface do not appear in hydroponic culture, but even so there are scores of possible interactions. The following are examples. The high levels of calcium supplied in most culture solutions help protect against these factors. Alkalinity forces zinc and especially iron out of solution, often leading to severe deficiencies of these metals despite the use of chelating agents to help keep them in solution.