Stunted growth and poor root development are typically signs of a phosphorus deficiency in a plant. Phosphorus plays a crucial role in root development and overall plant growth, so when levels are low, the plant struggles to produce strong roots and exhibits stunted growth. 

Also, calcium deficiency in plants can lead to stunted growth and poor development of roots, as calcium plays a crucial role in cell wall strength and integrity, particularly at growing root tips, which can be significantly impacted by its absence; resulting in reduced root extension and nutrient uptake. 

A deficiency in phosphorus is more likely to lead to stunted growth and poor development of roots compared to a calcium deficiency in plants; phosphorus plays a crucial role in cell division and root development, making it a key factor in overall plant growth. 

Phosphorus is vital for energy transfer within plants, and its deficiency directly impacts root growth and development, leading to stunted root systems and hindering nutrient uptake. While calcium is important for cell wall structure and stability, its deficiency primarily affects the tips of young leaves and shoots, causing symptoms like leaf curling and marginal browning, rather than significantly impacting root development in the same way as phosphorus.