Agronomy Degree Practice Exam

How does a deficiency in nitrogen typically manifest in plants?

1. Pale leaves

2. Stunted growth

3. Leaf drop

4. All of the above

The correct answer is: All of the above

A deficiency in nitrogen is crucial to understand because nitrogen is an essential macronutrient vital for plant growth, influencing various physiological processes. When plants lack nitrogen, several symptoms can emerge, reflecting the nutrient's importance in overall plant health. Pale leaves are a primary indicator of nitrogen deficiency. Nitrogen is a key component of chlorophyll, the molecule responsible for the green color in plants and necessary for photosynthesis. Without adequate nitrogen, chlorophyll production diminishes, leading to chlorosis, which typically manifests as pale or yellowing leaves, especially in the older foliage. Stunted growth is another common symptom of nitrogen deficiency. Since nitrogen is a major component of amino acids, proteins, and nucleic acids, its absence hampers the synthesis of these critical compounds. As a result, plants may exhibit reduced growth rates, smaller overall size, and a lack of vigor, leading to an overall stunted appearance. Leaf drop can also occur in nitrogen-deficient plants. As the plant struggles to maintain its metabolism without sufficient nitrogen, it may begin to senesce prematurely, leading to the shedding of leaves to conserve resources. This is particularly common in older leaves, as they are often the first to show signs of nutrient deficiency before the newer growth, as