Effect of orthophosphate and polyphosphate ratios on yield and quality of potato cultivars

Successful potato (Solanum tuberosum) cultivation depends on a variety of factors, of which fertilization forms an important component. Phosphorus (P) fertilizers differ not only in formulation (solid or liquid), but also in chemical form (orthophosphate or polyphosphate). To evaluate the response of potatoes to P sources, a study was performed to assess the productivity of potatoes under different ratios of orthophosphate and polyphosphate as P fertilizer. Potato cultivars (Mondial, Sifra, Lanorma, Innovator, Destiny, and Eos) were grown over two seasons using either 100% orthophosphate, 75% orthophosphate + 25% polyphosphate, 50% orthophosphate + 50% polyphosphate, or 100% polyphosphate. Plants demonstrated rapid vegetative development at the beginning when supplied with a balanced nutrient solution at an electrical conductivity (EC) of 1.5 mS cm(-1). Phosphorus applied as either 100% orthophosphate or 100% polyphosphate resulted in an increase in tuber number (24.5 and 20.8 tubers per plant, respectively) compared to 17.5 and 15.4 tubers per plant when 25% and 50% of the P was applied as polyphosphate. In both seasons the results indicated that applying P as orthophosphate had a superior effect on potato tuber fresh yield in comparison to applying P as polyphosphate.