Effects of shading, mulching and growing season on physiological indicators, anatomical characterization and quality of gladiolus flower stems

Crop management affects the anatomical and physiological characteristics of gladiolus floral stems. Particulary, shading screens are important in gladiolus production. The aim of the study was to evaluate the meteorological conditions, physiological indicators, stomatal characteristics, and quality of gladiolus flower stems grown in different seasons under shading screens and mulching. Field experiments were conducted during the four growing seasons: 1 (March-June 2019), 2 (August-November 2019), 3 (August-November 2020), and 4 (October-December 2021). Gladiolus cv. White goddess was grown in beds with and without mulch. Shading treatments included 35% black, silver, and red shading screens, and an unshaded control. Weather conditions during four growing seasons over two years were within the range of maximum and minimum temperatures suitable for the crop. The black and red shading screens resulted in higher stomatal density (374.9; 362.0 stomatal mm-2), which improved the photosynthetic rate of the leaf resulting in greater flower stem length (116.32 cm) and number of florets (19.00) in the red shading screen. The highest relative chlorophyll index (57.75) was recorded in season 2, which contributed to a greater accumulation of assimilates and resulted in longer stems and better-quality florets. Planting under a red shading screen and mulched soil produced longer stems (8.60 %; 9.05 %, respectively), and a greater number of florets in seasons 2 (8.43 %) and 4 (14.74 %), compared to growing unshaded control. The lowest percentage of damage to flower stems was found in the silver shading screen (3.6%) and mulched soil (6.7%). Long flower stems without damage to the sepals and petals, and with a large number of florets are of better quality, have greater ornamental value and are more attractive to flower consumers. Our results showed that planting in seasons 2 and 4, and using red shading screens and mulching soil, are sustainable and conservation soil-management practices to provide a favorable environment which allowed us to obtain high-quality gladiolus flowers. The results of this study are parameters for future research with different soil mulchings and shading screen colors.