Response of Potato Cultivars to Phosphate Fertilization in Tropical Soils with Different Phosphorus Availabilities

Potato cultivars have different strategies for dealing with phosphorus (P) deficiency in soil, and their response to P fertilization may vary because of differences in soil P availability. This study was performed to evaluate the effect of P fertilization rates (0, 125, 250, 500, and 1000 kg P2O5 per hectare) on the P uptake, fertilizer P recovery, tuber yield, and applied P use efficiency of five potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial) grown in Oxisols with low, medium, and high P availability in southeastern Brazil. The tuber yield of all potato cultivars increased similarly with increase in P fertilizer application up to rates of 500, 250, and 125 kg P2O5 per hectare in the soils with low, medium, and high P availability respectively. This increase was found despite the leaf P concentrations being lower than the deficiency limit of 2.5 g kg(-1) only in the soil with low P availability in the absence of P fertilizer application. The application of phosphate fertilizer in the planting furrow resulted in a greater increase in the leaf P concentration, plant growth, P uptake, number of tubers per plant, tuber mean weight, tuber yield, and P removal of the potato crop grown in the soil with low P availability compared with soils with high P availability. In soil with high P availability, P application rates higher than 125 kg P2O5 per hectare did not increase the number, size, and yield of tubers. The cultivar Mondial had the highest tuber yield, fertilizer P recovery, and applied P use efficiency, especially at the lower P application rates, but at a specific initial P availability, all cultivars responded to the same P application rate. The results indicate that phosphate fertilizer recommendations should be adjusted on the basis of soil P availability, and that it is not necessary to use different criteria to evaluate the P-nutritional status for individual potato cultivars.