Vegetative growth and phosphorus content in onion cultivars

The northern region of Brazil is still deprived of information regarding the behavior of onion cultivars and their response to phosphate fertilization. This work had the objective of evaluating the vegetative development and phosphorous accumulation in onion cultivars in Dianopolis, southeastern region of Tocantins, Brazil. The experimental design used was that of randomized blocks, with four replicates, in a 4 x 5 factorial scheme. We evaluated four onion cultivars (Diamantina, Red Creole, Baia Periforme and Primavera) in function of increasing levels of triple superphosphate, defined based on phosphorous doses, being them 0, 100, 200, 300 and 400 kg ha-1 of P2O5. We also evaluated the following traits: content of foliar phosphorous at 110 days after transplantation, plant height (cm) and number of leaves and pseudostem diameter (mm) at 120 days after transplantation. Phosphorous doses affected plant height, number of leaves and pseudostem diameter of cultivars Diamantina, Red Creole, Baia Periforme and Primavera. For plant height, the best response to phosphate fertilization was verified in cultivar Diamantina and Red Creole, with 3.48 and 3.38 g kg-1, respectively. The variation in the level of phosphate fertilization influences the phosphorus content of the cultivars studied.