What nutrient deficiency causes yellowing of leaves in plants?

Yellowing of leaves, also known as chlorosis, is often associated with nitrogen deficiency in plants. Nitrogen is a vital component of chlorophyll, the pigment responsible for the green color in plants and essential for photosynthesis. When nitrogen is deficient, plants are unable to produce enough chlorophyll, leading to a noticeable yellowing of older leaves first, as nitrogen is mobile within the plant and will be redirected to younger tissues.

This yellowing occurs because the plant is struggling to create the energy it needs for growth and sustaining overall health, impacting its ability to photosynthesize effectively. As the deficiency progresses, the yellowing may expand to younger leaves as well, but typically starts with the older leaves. This phenomenon is a key indicator for growers to recognize and rectify nitrogen deficiency in their plants to ensure healthy growth and development.