I can't tell you whether the medium contains available P but I think that you have the answer for yourself. To be sure you could test the foliage for P.

I'm unsure why you need to grow plants to capture the symptoms because there should already be plenty of images

All that aside, I'm interested in the idea of an app that would help farmers identify nutrient, disease and pest problems in major crops, because even in remote locations many farmers have mobiles with cameras. The idea would require some big data bases sitting in an expert system with a really simple front end that is as language independent as possible.

Phosphorus deficiency in plants manifests through stunted growth, often displaying dark green, purple, or reddish leaves due to anthocyanin accumulation. Poor root development, delayed maturity, distorted leaves, lower photosynthetic efficiency, and reduced seed production are common symptoms. Plants lacking phosphorus are also more susceptible to diseases. Accurate diagnosis, including soil testing, is crucial for confirming phosphorus deficiency and applying appropriate remedies, such as phosphorus-rich fertilizers, to address these symptoms effectively.

todos los síntomas de deficiencia de fosforo en la planta lo ha explicado de manera impecable el Dr Aniket Sunil, por lo que yo opino que para completar la idea solo faltan los análisis foliares a cada parte de la planta para determinar los contenidos de P en cada órgano de la planta en cada etapa fenológica del cultivo y contrastar con los rangos establecidos para el cultivo de trigo