Certified Crop Advisor Practice Exam

Which nutrient is typically associated with helping to regulate water in plants?

1. Nitrogen

2. Potassium

3. Phosphorus

4. Calcium

The correct answer is: Potassium

Potassium plays a crucial role in regulating water in plants, particularly through its influence on osmotic pressure and stomatal function. It is an essential macronutrient that helps maintain the plant's water balance by aiding in the opening and closing of stomata — the small openings on leaves through which gas exchange occurs. When potassium levels are adequate, stomata can efficiently regulate water loss during transpiration, ensuring that the plant does not lose excessive moisture while still facilitating gas exchange for photosynthesis. Additionally, potassium assists in the movement of water and nutrients within the plant by contributing to the turgor pressure in cells, which is vital for maintaining plant structure and function. This nutrient directly impacts the plant's ability to uptake water from the soil and manage its internal water content effectively. Other nutrients, like nitrogen, phosphorus, and calcium, while important for various metabolic processes and structural functions within the plant, do not have the same direct influence on water regulation as potassium does.