Duração do ciclo e danos por altas e baixas temperaturas em gladíolo em função da época de plantio

Abstract

The planting date is an important factor affecting the developmental cycle and quality of final product. Indications from the literature are that gladiolus is a species that can be cultivated throughout the year, but in some periods, adverse conditions may occur, reducing the quality of the flower. Two field experiments (Experiment 1: August 2011 to July 2012 and Experiment 2: August 2012 to July 2013) were conducted in Santa Maria, RS, Brazil, to quantify the influence of planting dates on the duration of the developmental cycle and on the quality of flower stems in gladiolus, identifying possible damages by high and low temperatures in the final product. It is concluded that it is possible to cultivate gladiolus throughout the year, but the duration of gladiolus cycle is higher when planting is carried out in periods of low temperatures, and this is important for scheduling the planting date, mainly for meeting specific market demand (commemorative dates). Extreme temperatures (above 35 ºC and below 0 ºC) reduce the commercial flowers quality and even cause the death of plants. Keywords: Gladiolus x grandiflorus Hort., development cycle, extreme temperatures, frost. RESUMODuração do ciclo e danos por altas e baixas temperaturas em gladíolo em função da época de plantio A época de plantio escolhida para cultivar uma espécie é fator determinante na duração do ciclo de desenvolvimento e na qualidade do produto colhido. O gladíolo é uma espécie que pode ser cultivada ao longo do ano, porém, em alguns períodos poderão ocorrer condições adversas ao cultivo, reduzindo sua qualidade. Foram conduzidos dois experimentos de campo em Santa Maria, RS, (Experimento 1: de agosto de 2011 a julho de 2012 e Experimento 2: de agosto de 2012 a julho de 2013) a fim de quantificar a influência da época de plantio na duração do ciclo e na qualidade das hastes de gladíolo, identificando possíveis danos por altas e baixas temperaturas no produto final. Conclui-se que é possível cultivar gladíolo ao longo do ano, porém a duração do ciclo de desenvolvimento do gladíolo é maior quando o plantio é realizado em períodos de baixas temperaturas, sendo esse dado importante para a programação da data de plantio, especialmente quando se desejar colher em datas pontuais (datas comemorativas). Temperaturas extremas (acima de 35 ºC e abaixo de 0 ºC) reduzem a qualidade comercial das hastes e até mesmo causam a morte da planta. Palavras-chave: Gladiolus x grandiflorus Hort., ciclo de desenvolvimento, temperaturas extremas, geada.

Cycle duration and quality of gladiolus floral stems in three locations of Southern Brazil

“…When planted in early dates, that occurs lower air temperatures (July and August), the cycle duration is extended for all cultivars, independent the cycle. This result was also found by Schwab et al (2018), which identified a change in the cycle duration when the planting was carried out in colder months, being prolonged when compared to those grown in the warmer months. The best planting date for these sites is during the second fortnight of July and first fortnight of August for presenting the best stems quality for three sites, because none of the cultivation sites was highlighted in relation to the quality stems.…”

Climate risk zoning for gladiolus production under three climate change scenarios

“…With respect to different developmental cycles of gladiolus, the tendency is that Late cultivars need to be planted earlier than Early cultivars to escape the occurrence of hightemperature damage during the reproductive period of the It is also noted that there will be a greater gap in production of gladiolus to meet certain seasons of the year in some regions such as Uruguaiana, Iraí, Santa Maria and Bagé, even if the less pessimistic scenario occurs (RCP2.6). To meet the demands during the hottest period of the year it will be necessary to develop techniques to reduce damage by high temperatures, like burned sepals (Schwab et al, 2018), such as more tolerant cultivars or the use of shading screens. The use of screens reduces the occurrence of sunburned peppers during the summer months in Southern Spain (López-Marin et al, 2011) and its effect on gladiolus crop still needs to be studied.…”

“…If the minimum temperature is lower than or equal to −2 ºC during one day or if −2 ºC < T min < 3 ºC during four days in a row during the reproductive phase, then the floral stem is killed by frost. Heat injury in PhenoGlad is considered when the maximum temperature is greater than or equal to 34 ºC during three consecutive days during the reproductive phase, causing severe burning of sepals (Schwab et al, 2018). If the maximum temperature is higher than 48 ºC, the upper lethal temperature is reached, and the crop is killed by heat.…”

“…Ornamental plants, especially those grown in open fields such as gladiolus, are greatly dependent on environmental conditions during the growing season. Changes in temperature may cause major losses in ornamental plants because the market requires that flowering must occur within a rather narrow time window to meet market demand (Snipen et al, 1999;Fisher & Lieth, 2000;Munir et al, 2015), and heat stress or frost may cause injuries on the floral stem, killing plants or reducing flower quality (Uhlmann et al, 2017;Schwab et al, 2018). 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).…”

A cultura do gladíolo como alternativa de diversificação e renda na pequena propriedade familiar

“…However, the late summer and early autumn (February, March and April) is also a suitable period for the production of quality flower stems (Schwab et al, 2015b). In the RS, the demand for gladiolus has been increasing in different celebratory dates, such as Mother's Day, Women's Day and also for the ornamentation of interiors, parties and events (Schwab et al, 2018). These different forms of use as cut flowers are shown in Figure 1.…”