Which is a symptom of nitrogen deficiency in soybeans?

The correct answer highlights a key symptom associated with nitrogen deficiency in soybeans. Distinctly yellow leaves, often referred to as chlorosis, occur due to insufficient nitrogen levels. Nitrogen is crucial for healthy plant growth, as it plays a vital role in chlorophyll production. When nitrogen is lacking, the plant is unable to produce adequate chlorophyll, leading to a yellowing of the leaves, particularly evident in older leaves where nutrients are translocated to support new growth.

This symptom is one of the first visible signs of nitrogen deficiency, as nitrogen is mobile within the plant. Since older leaves experience a reduction in chlorophyll first, the distinctly yellow appearance becomes more pronounced. This understanding is critical for farmers and agronomists when assessing soybean health and managing nutrient applications effectively to ensure optimal crop production.

In the context of other symptoms of nitrogen deficiency, pale green leaves and stunted growth could result from various nutrient deficiencies, and while V-shaped yellowing at leaf tips is typically associated with phosphorus deficiency, older leaves showing symptoms first aligns with the nitrogen deficiency pattern as well. However, the specific portrayal of distinctly yellow leaves as a primary indicator makes this answer the most accurate in identifying nitrogen deficiency symptoms in soybeans.