18. What role does magnesium play in enzyme activation in papaya plants?
Answer: Activates enzymes involved in photosynthesis and energy production in papaya crops
Magnesium acts as a cofactor for many enzymes involved in energy production and carbohydrate metabolism in papaya plants. A deficiency can disrupt these processes, leading to reduced plant growth and fruit yield.

19. What is a common foliar symptom of advanced magnesium deficiency in papaya plants?
Answer: Brown necrotic spots on older leaves of papaya plants
As magnesium deficiency progresses, older leaves in papaya plants may develop brown necrotic (dead) spots, eventually leading to leaf drop.

20. What is the best way to prevent magnesium deficiency in papaya crops?
Answer: Regular application of magnesium-rich fertilizers in papaya farming
Explanation: To prevent magnesium deficiency in papaya crops, farmers should apply magnesium-rich fertilizers such as magnesium sulfate (Epsom salt) or dolomite lime, especially in soils prone to magnesium depletion.