Magnesium deficiency of hydroponic and container grown basil

Basil (Ocimum basilicum) is the most commonly grown greenhouse herb crop. Basil is sensitive to magnesium deficiency. Visual symptoms of magnesium deficiency appear first on old and recently mature leaves as a slight interveinal chlorosis (yellowing). This article will cover the progression of visual symptoms of magnesium deficiency, common causes of the deficiency, target leaf tissue elemental magnesium, and corrective actions for both hydroponic and container grown plants.

by Neil Mattson - nsm47@cornell.edu

Magnificent magnesium
Magnesium (Mg), is an essential plant nutrient. As a macronutrient, Mg is required in relatively large amounts. On average, plants require Mg in greater quantity than all other elements except nitrogen (N) and potassium (K). Magnesium is a central building block to chlorophyll, the pigment that makes plants appear green and the molecule responsible for capturing lighting in photosynthesis. Magnesium is also involved in several key enzymes related to carbohydrate metabolism and in protein synthesis. Suffice it to say, plants cannot function properly without enough magnesium.

Figure 1. Interveinal chlorosis on mature and recently mature leaves of basil is an early symptom of magnesium deficiency. Roots Photo: Neil Mattson, Cornell University

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