Is Phosphorus (P) mobile in the plant?

Phosphorus (P) is indeed considered mobile within plants, particularly in the phloem, the vascular tissue responsible for the transport of nutrients and photosynthates. This mobility is crucial for plant growth and development since phosphorus plays a vital role in several key physiological processes, including energy transfer (as part of ATP), photosynthesis, and nucleic acid synthesis.

In young plants, phosphorus can be relocated from older tissues to support new growth because it is involved in root and flower development. Its mobility is essential in situations where plants may need to adapt to low phosphorus availability in the soil; by reallocating phosphorus from older to younger tissues, the plant can optimize its growth and reproductive success.

This characteristic stands in contrast to other nutrients like calcium and iron, which tend to remain relatively immobile within plants and are usually confined to the sites where they are taken up. Therefore, the fact that phosphorus can be transported as needed emphasizes its mobility within the plant.