Abstract
ABSTRACT The objective of this study was to develop a climate risk zoning for damage to gladiolus due to low and high temperature under climate change scenarios projected by the end of the century in the Rio Grande do Sul State, Brazil. The PhenoGlad model was used in this study to determine the recommended periods for planting gladiolus throughout the year across the Rio Grande do Sul State. The model was run for daily planting dates (from 01 January to 31 December), for different gladiolus developmental cycles (Early, Intermediate I, Intermediate II and Late). The climate change scenarios were from CMIP5: RCP2.6, RCP4.5 and RCP8.5, representing optimistic, intermediate and pessimistic scenarios of greenhouse gases emission, respectively. Planting dates were considered recommended when crop damage, due to high or low temperatures, occurred in less than 10% of the years. Warmer regions like Uruguaiana and Iraí have the shortest recommended time for planting throughout the year in the three climate change scenarios. Plantings between August and December are predicted to be the most affected and are not recommended because of the higher chance of damage from high temperatures. Colder regions like Bom Jesus will be favored in climate change scenarios since there will be an extended recommended period for planting in the seasons of the year that currently suffer damage by low temperatures. To meet demands of gladiolus during the hottest period of the year, it will be necessary to develop techniques to reduce damage from high temperatures in the crop, such as more tolerant cultivars or the use of shading screens on the crop.
Highlights
Gladiolus (Gladiolus x grandiflorus Hort.) is one of the most important bulb flower crops worldwide (Thakur et al, 2015)
The objective of this study was to develop a climate risk zoning for gladiolus under climate change scenarios projected by the end of the century in the state of Rio Grande do Sul, Brazil, considering damage due to low and high temperatures
These six regions of the State have the greatest climate contrast on air temperature, altitude, continentality and oceanity.The recommended period for planting gladiolus in the current zoning is much larger than the baseline period, mainly for the regions of Uruguaiana (Figure 2A), Iraí (Figure 2B), Santa Maria (Figure 2D) and Bagé (Figure 2E). This can be explained because the minimum temperatures are lower in the current zoning (Figures 3A, C, G, I) and maximum temperatures are much higher in the baseline period than in the current zoning (Figures 3B, D, H, J). This indicates that, for the baseline period, a shorter period throughout the year is recommended for planting due to the higher occurrence of damage caused by high temperatures that coincide with the reproductive phase of the crop (Uhlmann et al, 2017)
Summary
Gladiolus (Gladiolus x grandiflorus Hort.) is one of the most important bulb flower crops worldwide (Thakur et al, 2015). In Brazil, gladiolus has become an important cut flower for small farmers, because it is an easy-to-produce crop that requires low initial cost and can be cultivated in the open field. The expansion in flower production in the state of Rio Grande do Sul, Brazil, is important for meeting the demand of the State, which currently imports about 90% of cut flowers (IBRAFLOR, 2019). Ornamental plants, especially those grown in open fields such as gladiolus, are greatly dependent on environmental conditions during the growing season. The climatic risk zoning is a tool to assist farmers in defining the best periods for the production of quality floral stems, considering damage by high and low temperatures in the floral stem (Uhlmann et al, 2020)
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