Abstract
ABSTRACT: Gladiola is an important cut flower worldwide and scheduling field gladiola production is largely dependent on planting at the correct time since its development is controlled by the air temperature. The aim of this study was to configure a planting window of gladiola in order to harvest spikes to be sold on All Souls' Day and Mother's Day holidays in the state of Rio Grande do Sul, Brazil, taking into account the El Nino Southern Oscillation (ENSO) phases. The PhenoGlad model, a dynamic process-based simulation model that simulates gladiola phenology on a daily time step was used in this study. Daily minimum and maximum temperatures over 55 years (1961-2015) from 18 weather stations across Rio Grande do Sul state, Brazil, were used as input data in the PhenoGlad model. The optimum planting window was simulated for each maturity group, location and ENSO phase. For harvesting on All Souls' Day, the optimum planting window had greater variation among the different ENSO phases. For Mother's Day, only Very Strong El Nino events affected the development of gladiola, indicating the weak signal of the phenomenon at this time of the year. A case study in a commercial farm demonstrated the importance of these results for farmers. The planting window for production on Mother's Day in a Neutral year was successfully configured. Determining the optimum planting window by considering the ENSO effect led to a more precise scheduling of gladiola production in southern Brazil.
Highlights
The cut flower sector is the most important in floriculture, followed by live plants, bulbs and foliage sectors
Site and weather data This study was conducted in Rio Grande do Sul (Figures 1A and B), southern Brazil, wich presents vegetation composed of Araucarias conifers, the Pampas prairies, coastal vegetation and the Atlantic Forest
The cumulative leaf number (CLN) simulated by the PhenoGlad model was close to the observed data, with a root mean square error (RMSE) of 0.65 leaves (n = 201)
Summary
The cut flower sector is the most important in floriculture, followed by live plants, bulbs and foliage sectors. In southern Brazil, which includes Rio Grande do Sul, the El Niño-Southern Oscillation (ENSO) is a major cause of interannual variability in rainfall (Grimm et al, 1998; Aceituno et al, 2009) and temperature (Grimm, 2003; 2004; Barros et al, 2002). There have been reports in Rio Grande do Sul that, during the last 10 years (2009-2018), in certain years, farmers who planted the bulbs on the same day of the year failed to have gladiola flowers ready for All Souls’ Day, i.e flowers were either ready too early or after the target day, because of climate variability over the years
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