Abstract
Information related to phosphate fertilization and coated phosphate fertilizer in onion is scarce. Thus, this study was carried out to evaluate agronomic efficiency, production and nutritional characteristics of triple superphosphate coated with polymers in onion cultivated in contrasting texture soils. Two experiments were carried out under protected conditions in pots containing 5 kg soil. The experimental design was completely randomized with treatments arranged in a 2 x 5 factorial: triple superphosphate (TSP) and polymer-coated triple superphosphate (TSP+P) applied in five phosphorus rates: Dystroferric Red Latosol (LVdf) (clayey) = 0; 100; 200; 400; 800 mg P2O5 kg-1, and Quartzarenic Neosol (sandy) = 0; 75; 150; 300; 600 mg P2O5 kg-1, with three replications. Results indicated that polymer-coated TSP showed no difference for bulb mass and agronomic efficiency for phosphorus fertilization. Agronomic efficiency of phosphorus fertilization decreased with the increase in the amount of phosphorus applied. Phosphorus accumulation for onion bulb cultivated in Dystroferric Red Latosol (LVdf) was higher with the use of polymer-coated triple superphosphate. Growth, production and nutritional characteristics in onion were affected by phosphorus. The highest bulbs mass production and phosphorus accumulation occurred at the doses of 783; 629 mg kg-1 P2O5 (Dystroferric Red Latosol - LVdf), and of 406; 600 mg kg-1 P2O5 (Quartzarenic Neosol -RQ).
Highlights
IntroductionOnion is the third most important vegetable crop grown in Brazil, after potatoes and tomatoes (BETTONI, 2013; MENEZES JÚNIOR; GONÇALVES; KURTZ, 2013)
Regarding the economic aspects, onion is the third most important vegetable crop grown in Brazil, after potatoes and tomatoes (BETTONI, 2013; MENEZES JÚNIOR; GONÇALVES; KURTZ, 2013)
For all P2O5 doses applied in onion plants, regardless of the triple superphosphate (TSP) form, with or without coating, there was an increase in bulbs mass compared to the control
Summary
Onion is the third most important vegetable crop grown in Brazil, after potatoes and tomatoes (BETTONI, 2013; MENEZES JÚNIOR; GONÇALVES; KURTZ, 2013). P deficiency causes reduction in the root system growth, in the leaf area, in the bulbs mass, in yield, and delays onion maturation (MENDES et al, 2008; RIZK et al, 2012). In this context, P has great importance in the management of soil fertility cultivated with vegetables, which in general draw large amounts of this nutrient over the cropping years. P has great importance in the management of soil fertility cultivated with vegetables, which in general draw large amounts of this nutrient over the cropping years This nutrient is important since the largest part of the Brazilian soils presents high fixation capacity and low P availability (LEITE et al, 2009). The slow- or controlledrelease fertilizer is a possible strategy to act promoting synchronization between the phosphorus absorption curve of the culture and the release of the fertilizer’s nutrients for soil solution (DU; ZHOU; SHAVIV, 2006; DAI. et al, 2008; SHI et al, 2009)
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