HARVEST HANDLING AND PHOSPHATE NUTRITION IN YERBA-MATTE (Ilex paraguariensis) CULTURE DURING PRODUCTION STAGE

ABSTRACT

Successive harvesting of leaves (FO) and thin branches (GF), with no nutrient reposition by fertilization, have been resulting in continuous decrease in Brazilian productivity of mate in the last 20 years. So, the objective of this work was to evaluate the influence of harvest interval and phosphate nutrition on the availability of phosphorus (P) in the soil, on the productivity, as well as on the nutritional status of mate plants. The experiment was conducted in São Mateus do Sul/PR, in an Oxisol, where doses of 0, 20, 40, 80, 160 and 320 kg ha-1 of P₂ O₅ were evaluated for harvest intervals of 12, 18 and 24-months in a seven-year-old mate plantation. Soil P availability, at 0-10, 10-20 and 20-40 cm depth, was assessed. Harvest consisted on removal of approximately 95 % of the tree canopy formed since the previous harvest. Harvested green material was individually determined for FO, GF and thick branches (GG), where FO + GF corresponded to the commercial mate (ECOM). The relationship between green/dry mass (MV/MS) was also evaluated for all plant components, as well as the content of P in FO, GF and GG. Phosphate fertilization increased the availability of P in the upper soil layer and the plant responded positively to P application by increasing the dry mass of all the assessed components. Harvests with longer intervals resulted in greater productivity of ECOM, but for maximizing productivity, high doses of fertilizers are needed. Twelve month intervals are insufficient to allow the plant to recover from the harvest impact, even if well-nourished in phosphorus.

Keywords:
foliar content; phosphorus availability; productivity; nutrient use efficiency.