Produção e qualidade pós colheita de gladíolo cultivado em vaso sob diferentes níveis de irrigação

Abstract

Gladiolus is one of the most popular cut flowers in Brazil and as its commercialization depends on quality criteria based on morphological and visual characteristics, it becomes relevant to evaluate how the occurrence of water deficit affects these commercial parameters and the longevity of the stems after the harvest. This work aimed to study the influence of irrigation levels and planting time on the commercial quality of gladiolus flower stems. Cultivation cycles were carried out in a greenhouse located in the Horticulture Sector of UFRRJ, in the municipality of Seropédica-RJ, Brazil, from 07/09/18 to 11/27/18 and from 12/04/19 to 06/26/19. The experimental design was randomized blocks with 5 replications, composed by four levels of the irrigation factor (L1 = 45%, L2 = 60%, L3 = 80% and L4 = 100% of the water volume applied by the system) and two levels of the planting time factor (winter/spring 2018 and autumn/winter 2019). Irrigation management was performed using the automatic irrigation controller (AIC), installed in 2 pots from L4 treatment. The substrate used was a mixture of medium texture soil material, removed from the 0-20 cm layer, and manure in the proportion 2:1 (v/v), placed in 11 L pots where 3 bulbs 10 cm apart were planted and at a depth of 10 cm. When the plants reached the harvest point, the commercial parameters of floral stem length, floral stem diameter and spike length were evaluated, in addition to the number of flowers. In both cycles the plant height was evaluated weekly, while the leaf area and number of leaves were evaluated at 66 days after planting (DAP). In the autumn/winter cycle (2019), leaf area and chlorophyll were evaluated at 28, 38, 52 and 66 DAP, and stomatal conductance was evaluated at 40 DAP. At the end of the cycle, the stems were subjected to postharvest analysis to assess longevity, fresh weight, speed of floral opening and solution absorption. At 151 (winter/spring) and 154 DAP (autumn/winter), the bulbs were harvested, when their mass and diameter were evaluated. In total, 5.24; 6.68; 8.65 and 10.81 L plant-1 were applied in winter/spring and 4.91; 6.58; 8.25 and 10.25 L plant-1 in autumn/winter planting in treatments L1, L2, L3 and L4, respectively. The stems showed better commercial classification in the treatments corresponding to 80% and 100% of the volume applied by the controller, presenting the highest values for the analyzed variables. The treatments L3 and L4 also stood out regarding the fresh mass and lower speed of floral opening, with no difference between the longevity of the stems (8 days). Likewise, the production of bulbs was higher in these treatments, with bulbs of large size while in L1 bulbs of medium size were obtained. In the winter/spring cultivation, temporary wilt and slight defects in the stems characterized by burns in the sepals of the florets were observed, symptoms not observed in the autumn/winter. Influence of irrigation levels on the commercial parameters of the gladiolus was observed, with a greater loss of quality at the level of 45% of the applied volume, greater speed of floral opening and less longevity in winter/spring planting.