Louisiana Landscape Horticulture State Practice Exam

Macronutrients for plants are essential nutrients that are needed in larger quantities for growth and development. Nitrogen, phosphorus, and potassium are the three primary macronutrients, often referred to as N-P-K.

Nitrogen is crucial for the synthesis of amino acids, proteins, and chlorophyll, facilitating growth and the formation of new plant tissues. Phosphorus plays a key role in energy transfer through ATP, root development, and flowering processes. Potassium is important for regulating various physiological functions, including water uptake and enzyme activation.

While calcium and magnesium, found in the other choice, are also important macronutrients, they are secondary compared to nitrogen, phosphorus, and potassium, which are needed in higher quantities. Sulfate, mentioned in that option, is a micronutrient and not categorized as a macronutrient.

The other choices list micronutrients or elements that are needed in trace amounts and do not fulfill the definition of macronutrients required for the fundamental biochemical functions and structural integrity of plants.