Magnesium Nutrient Deficiency in Plants

Form

Taken up as ionic Mg²⁺, Magnesium is essential for chlorophyll and sugar formation, playing a central role in maintaining green leaf area and photosynthesis. In addition, Magnesium is vital for activating enzymes that promote growth and stimulate immune system responses.

Function

Magnesium promotes canopy and fruit development, sugar formation and the uptake of major nutrients, particularly Nitrogen and Potassium. Magnesium nutrient deficiency results in poor nutrient recovery, low growth rates, increased biotic stress and early senescence.

Symptoms

Magnesium nutrient deficiency affects older leaves first. The main veins on the leaf remain dark green, while the interveinal leaf area becomes uniform pale green to yellow, eventually turning brown and necrotic.

Significance

Magnesium stress can affect plant uptake of Nitrogen and Potassium, leading to early maturity and poor development of fruit, with low sugar content. In addition, plant defence and disease resistance can be restricted. Magnesium nutrient deficiency is often worse in compacted or alkaline soils, during hot, dry growing conditions and when crops are fed high levels of Nitrogen-Potassium fertiliser.

Actions

Check soil status and correct if necessary. Foliar fertilizer treatment as soon as symptoms appear can be very effective. Routine applications of foliar Magnesium can improve the later stages of yield building and quality forming.