The low content of phosphorus in tropical soils makes essential the research about fertilization in crops which are poorly studied such as yam. Thus, this study aimed to evaluate the yam productivity (cultivar Da Costa) depending on phosphorus doses and harvest seasons. From February to December 2009, an experiment was carried out using the randomized blocks experimental design in subdivided plots, with four replications. In the plots six doses of phosphorus were evaluated (0, 100, 200, 300, 400 and 500 kg ha-1 of P2O5), and in the subplots two harvest seasons (seven and nine months after planting). The highest weight of tubers in seven and nine months was 1.94 and 2.20 kg with 245 and 240 kg ha-1 of P2O5, respectively. There was no significant effect of phosphorus doses on the total productivity in seven months and the average value was 13 t ha-1. The highest marketable productivity was 11.8 t ha-1 with 266 kg ha-1 of P2O5. In nine months, the highest total and marketable yield (24.7 and 20.5 t ha-1, respectively) was achieved with the application of 285 and 226 kg ha-1 of P2O5, respectively. The yield of tubers classified as first was 80 and 90% in seven and nine months, respectively, and was obtained with the application of 320 and 277 kg ha-1 of P2O5, respectively. The economic doses were 219 and 233 kg ha-1 of P2O5 to obtain 20.19 t ha-1 and 12.88 t ha-1 of marketable tubers in seven and nine months, representing increments of 19.17 and 3.9 t ha-1 in comparison to no application of phosphorus, respectively.
Dioscorea cayennensis; phosphate fertilization; quality and production of tubers
