Certified Professional Horticulturist (CPH) Practice Exam

Magnesium is essential for the production of chlorophyll, the green pigment found in plants that plays a critical role in photosynthesis. Chlorophyll molecules contain a magnesium ion at their core, which is vital for capturing light energy. Without sufficient magnesium, plants struggle to produce enough chlorophyll, impacting their ability to photosynthesize effectively. This can result in poor growth and nutrient deficiencies, as the process of converting sunlight into chemical energy is severely hindered.

Other nutrients, while important for plant health—such as nitrogen for growth and amino acid formation, and potassium for overall plant function—do not directly contribute to the formation of chlorophyll in the way that magnesium does. Thus, magnesium's role as a central component of chlorophyll uniquely qualifies it as the crucial nutrient for this vital plant component.