Which nutrient deficiency is most likely to cause yellowing leaves and poor growth in plants?

The nutrient deficiency most likely to cause yellowing leaves and poor growth in plants is nitrogen. Nitrogen is a crucial component of chlorophyll, the pigment responsible for the green color in plants and essential for photosynthesis. When nitrogen is deficient, plants cannot produce adequate chlorophyll, leading to a visible yellowing of the leaves, often termed chlorosis. The overall growth of the plant is also negatively impacted because nitrogen is critical for plant metabolism, growth, and development, as it is a key component of amino acids, which are the building blocks of proteins. Insufficient nitrogen availability can stunt growth, reduce leaf size, and impact the fruit or flower production.

Other deficiencies, such as those of phosphorus, iron, and magnesium, can also cause yellowing and affect growth but typically show different symptoms or manifest at different stages of plant development. Phosphorus deficiency might lead to dark green or purplish leaves, while iron deficiency is primarily recognized by yellowing between the veins of new leaves. Magnesium deficiency often results in yellowing or necrosis at the edges of older leaves. However, the hallmark of nitrogen deficiency is the overall yellowing of the entire plant, making it the most likely cause of such symptoms in a broader context.