Produção, vernalização e fase de brotação de cormos de gladíolo

Abstract

Gladiolus (Gladiolus x grandiflorus Hort.), is a cut flower propagated by corms, very popular for its diversity of colors and robustness. The objectives in this dissertation were: (i) describe a production protocols for gladiolus corms from the floral stem production, (ii) verify the answer of gladiolus to vernalization and evaluate a nonlinear vernalization response function, (iii) characterize the effect of sprouting stages and the planting depths of gladiolus corms in the sprouting phase, in the occurrence of harvest point date and in the perform an analysis of the performance of the PhenoGlad model in relation these factors. The technique of producing gladiolus corms is little known and due the scarcity of information, a corm production protocol has been described, step by step, for this culture. Field experiments were conducted during three years (2016, 2017 and 2018) to determine how the management of corms can affect the production of gladiolus floral stems. Gladiolus corms were exposed a different vernalization treatments: four temperatures (0,5°C, 5°C, 10°C and 20°C) during five storage periods (2, 4, 6, 8 and 10 weeks). Five planting depths have been tested (5 cm, 10 cm, 15 cm, 20 cm and 25 cm) and four developmental stages during sprouting phase of gladiolus corms (S1, S2.1, S2.2 and S2.3) were tested. Phenology data were evaluated starting at planting in different experiments and planting dates. The PhenoGlad model was used for simulating the harvest point date and compare with observed data in the field. To get a propagation material with quality, care should begin at the time of harvesting the floral stem produced by the mother corm. After a period of growth in the field, corms need to be harvested, cleaned, cured and vernalized. This process takes about six months before a new planting can take place, in order to have plants to be able to bloom. Knowledge of this technique is important for reducing production costs and ensuring production sustainability and a response function can help to bridge this gap. The response of gladiolus development to vernalization under the conditions provided in this study was not well simulated by the proposed function. Separating the effect of breaking dormancy and vernalization at low temperatures is a challenge and it is therefore important to determine the cardinal temperatures vernalization in gladiolus. When gladiolus corms are planted at greater depths a delay in the emergence speed of plants is observed. This lower emergence rate is also observed when corms are planted with less sprouting. The delay in emergence reflects the harvest point date of gladiolus, but does not reduce the quality of floral stems for commercialization. From these factors, it is understood that making change to the source code oh the PhenoGlad model was not necessary, whereas in practice, even overestimating the model, it correctly adjusts the harvest point date of floral stems, in advance.