Influence of nitrogen, potassium and phosphate fertilizers on quality and longevity of gladiolus

The gladiolus is one of the most cut flowers produced and marketed in Brazil and worldwide. This work was conducted with the objective to evaluate the use of nitrogen and potassium fertilization associated with different sources and levels of phosphorus in the quality and durability in postharvest gladiolus (Gladiolus hortulanus L. cv. T704 ) cultured in oxisoil. It was used the experimental design randomized blocks and the treatments were arranged in sub-subplots. The plots were allocated the presence or absence of nitrogen and potassium fertilization (NK ), subplots sources of phosphorus (triple superphosphate, superphosphate and bone meal) and the sub-subplot the five P rates (0 , 75 , 150 , 225 and 300 kg ha-1) fertilizers studied . Plants were evaluated on the number of flower buds, number of colored buttons, and number of open flowers, leaf quality, and flower quality, quality of the stem, plant height, and length of floral spike, diameter and durability flower. Regardless of treatments and combinations studied, the leaves produced were classified as optimal. The combined action of the three factors studied (p < 0.05) was observed only on the diameter and durability of flowers. It was concluded that NK fertilization is crucial and that the dosages used in this study were sufficient to obtain class I quality gladiolus. The use of triple superphosphate is more efficient when the goal of flowers and durability, the superphosphate, when objective quality of the stems. Phosphorus levels between 150 and 160 kg ha-1 are sufficient to obtain durability and quality of the flowers and stems of this cultivar.