NUTRIENT STORAGE POOL CONCENTRATIONS IN PLANTS AS DIAGNOSTIC INDICATORS OF NUTRIENT SUFFICIENCY

Macronutrients accumulate as free ions in all plant organs when suppli es are abundant but growth requirements are generally satisfied before high concentrations are attained. Low threshold concentrations are ne cessary to ensure maximum growth and in wheat leaves these are around 10 mM nitrate, 5 mM phosphate, 0.5 mM sulfate and 130 mM potassium. Th e measurement of inorganic ion concentrations in leaves has potential as a diagnostic tool and might enable soil nutrient supplies to be mor e accurately matched with crop needs.