Phosphorus Nutrition and Tuber Yield of Potato Crop As Affected By Phosphorus and Silicon Fertilizations.

In Brazil, as in most tropical countries, one of the main limiting factors to high potato (Solanum tuberosum L.) yield is the low phosphorus (P) availability in soil. Thus, as potato is a crop with low ability to uptake P from soils with low available P, high amounts of P fertilizer are normally applied for an appropriate potato plant development and high tuber yield. Silicon (Si) may increase the P availability in soil by competition with P by the same adsorption sites. Thus, Si fertilization can be a promising technique to improve the use efficiency of applied P and increase tuber yield of potato crop. The aim of this study was to evaluate the effect of Si fertilization on the P uptake and tuber yield of potato crop (cv. Agata) grown under different P fertilization rates. A field experiment was carried out in a clayey Oxisol with low-medium P_{resin-extractable} content (28 mg dm^-3) in Itaí, São Paulo State, southeastern region of Brazil. The experimental design was randomized complete blocks in 4x3 factorial scheme, with four replications. Treatments were constituted of four rates of P (0, 125, 250, and 500 kg ha^-1 P₂O₅) combined with three rates of Si (0, 75, and 300 kg ha^-1 Si). Phosphorus was supplied as triple superphosphate (41% P₂O₅) and Si as FertiSilica (22.4% of soluble Si) in powder form. Both P and Si fertilizations were applied into planting furrow. Phosphorus fertilization increased the plant growth, leaf P concentration, P uptake, and tuber yield of potato crop, regardless of Si application. The highest tuber yield was reached with the estimated rate of 450 kg ha^-1 P₂O₅. Silicon supplying did not affect the P nutrition and tuber yield of the potato crop. There was no significant P × Si interaction for the evaluated variables.