**2. Phosphorus in plant growth and development**

Plant growth heavily relies on inorganic nutrients; predominantly N, and P both of which are often limited in the environment, hence these nutrients are frequently administered as fertilizers to plants [11]. An optimal P fertilization can enhance plant biomass yield and improve antioxidant potential [12]. Increasing P-levels can also result in improved growth parameters, including fresh and dry weight, floral number, plant height, and essential oil concentration [13]. Additionally, P plays a crucial role as a metabolic and regulatory nutrient element. However, the interaction of P with other minerals is often stronger than its individual action [14]. Particularly in the dark phase of photosynthesis, the availability of P can significantly impact the efficiency of the CBB cycle and the production of energy-rich molecules such as ATP and NADPH.

P plays a crucial role in enhancing a plant's ability to resist and tolerate diseases, which can cause significant reductions in both crop yield and quality [15]. Its application is known to enhance plant growth and also to increase resistance to various biotic stresses. For instance, when a pathogen invades a plant, P in the form of ATP is released into the extracellular space, where the plants recognize it as a signal that there is cellular damage [16]. In turn, this signal activates the plant's defense response to fight off the pathogen. Therefore, ATP is a signaling molecule for the defense response activation in the plant [17]. Further, P-deficiency can have a profound impact on plant growth and productivity, leading to reduced root growth, delayed flowering, impaired seed development, and decreased crop yield [4, 5]. In addition to these direct effects, phosphorus deficiency can also influence the plant's ability to acquire other essential nutrients, such as N, K, and micronutrients, further exacerbate the impact on plant growth and development [18, 19].

*Role of Phosphorus in the Photosynthetic Dark Phase Biochemical Pathways DOI: http://dx.doi.org/10.5772/intechopen.112573*
