Effects of water replacement levels and nitrogen fertilization on growth and production of gladiolus in a greenhouse

The gladiolus is a cut flower used for interior decoration. It is a short cycle, easy driving crop with low implantation costs and fast payback. These factors allow for its cultivation in small areas in which commercial production of bulbs for domestic and foreign markets is also possible. Furthermore, it has high economic value because it is among the most important cut flowers grown in Brazil and is the third in product volume. This study aimed to evaluate the effect of different water replacement levels in the soil (50%, 75%, 100%, 125%, 150% of field capacity water volume) and nitrogen doses (0, 30, 60, 90, 120 mg dm−3) on crop growth and production in a greenhouse. The species studied was the Gladiolus x grandiflorus L., White Friendship variety. The experimental design consisted of randomized blocks in a 5 × 5 factorial scheme with four replications. The growth and yield of gladiolus were characterized by the following variables: number of leaves, total plant height, floral spike and stem length, number and diameter of flowers, floral dry mass stem and number of days to bolting and flowering. Using the statistical software Sisvar, data were subjected to an analysis of variance at the 5% level of significance using the F test and to polynomial regressions. For nitrogen fertilization, there was a significant response only to the variable of floral stem dry mass. For the water replacement levels, responses were significant for all of the variables analyzed. The management of water irrigation at replacement levels above 75% of field capacity allowed for the length of the floral stems to be classified for commercial purposes, and for the number of flowers, water replacement levels above 100% provided a better commercial classification.