4.8—Water and inorganic ions in plants

Plants absorb water and inorganic ions through roots and move them in xylem. Water supports photosynthesis, transport, turgor and temperature regulation; nitrate, magnesium and calcium ions support different molecules and structures.

Nitrate is needed for amino acids, proteins, DNA and chlorophyll. Magnesium is part of chlorophyll. Calcium contributes to cell-wall structure and normal growth. A shortage produces characteristic symptoms, but the symptom alone does not identify the cause without controlling other minerals.

A nutrient-broth experiment can compare seedlings receiving high, medium or low calcium while keeping light, age and other ions constant. Measure mass change and inspect symptoms rather than attributing every difference to water.

Water is a transport medium, not a replacement for mineral nutrients. A deficiency investigation needs matched seedlings, replication and controls so ion concentration is the tested variable.