Soaking curve and effect of temperature on the germination of daisy seeds

Abstract

The soaking curve and the effect of temperature on the germination of daisy seeds (Chrysanthemum leucanthemum) were characterized in this study. To determine the soaking curve, four samples of 0.5 g of seeds were soaked in germitest paper moistened with distilled water and maintained in germinator at 25ºC. The seeds were weighed in periods of 0, 3, 6, 9, 12, 24, 36, 48, 60, 72, 84 and 96 hours using a precision digital balance of 0.0001 g. A triphasic pattern germination curve was adjusted, allowing the determination of the beginning and duration of the phase II of the germination process. The germination test was carried out with four replications of 50 seeds disposed in "Gerbox" boxes and placed in germinators at the temperatures of 20, 25, 30 or 20-30ºC. A completely randomized experimental design was used with four replications of 50 seeds. The data were submitted to the analysis of variance and the averages were compared by the Tukey test, at 5% of probability. For analysis of accumulated seed germination, regressions were adjusted based on period of experiment. The seeds presented a triphasic pattern of germination and the phases I and II lasted 12 and 48 hours, respectively. The best temperature for the germination of the seeds is 25ºC. The temperature of 30ºC promoted the thermoinhibition of germination and increased the dead and dormant seeds and abnormal seedlings.

Remojo de semillas de Alcantarea imperialis (Carrière) Harms en tratamientos térmicos previos a la germinación bajo dos condiciones de luminosidad

“…Apesar de essas relações se tratarem de processos físicos que fornecem a maior hidratação das sementes, isso não foi suficiente para acelerar o processo germinativo em comparação a tratamentos com baixa temperatura e controle. Altas temperaturas podem induzir ou reforçar dormência primária e/ou secundária em sementes, diminuir a solubilidade de oxigênio, inibir processos enzimáticos, reduzindo as taxas de germinação das espécies e promovendo termoinibição (ALI; ELOZEIRI, 2017;BEWLEY et al, 2013;PÊGO;GROSSI;BARBOSA, 2012;TOH et al, 2008). Baixas temperaturas podem retardar o crescimento radicular e foliar de espécies tropicais, promover mudanças na mobilização de carboidratos não estruturais, na sinalização hormonal de giberelina e reduzir a velocidade de germinação (HUA, 2009;MOLLO et al, 2011;NIEVOLA et al, 2005).…”

Assessing Competitiveness of Fine Fescues (Festuca L. spp.) and Tall Fescue (Schedonorus arundinaceous (Schreb.) Dumort) Established with White Clover (Trifolium repens L., WC), Daisy (Bellis perennis L.) and Yarrow (Achillea millefolium L.)

“…This might explain the difference in weed cover between the two years, as average daily temperatures were within this optimal range on 74 days in 2018 compared to only 57 days in 2019. Maximum germination rates (82%) for yarrow under frequent irrigation rates have been reported between 22 • C to 29 • C [40], and 25 • C was reported to be an optimal temperature for germination of daisy [41]. Therefore, and regardless of weed treatment, germination of weed seed was favored in 2018 due to higher average temperatures, resulting in greater weed cover.…”

Impactos Negativos Dos Pesticidas Nas Comunidades De Abelhas

“…Taubert (Guimarães et al, 2011), pinhão manso (Evencio et al, 2011;Smiderle et al, 2013;Araújo et al, 2014), araticum-de-terra-fria -Annona emarginata (Schltdl.) H. Rainer) , em pastagem -Urochloa brizantha e U. ruziziensis (Derré et al, 2013), em ornamental -margarida -Chrysanthemum leucanthemum (Pêgo et al, 2012) e agrícola -soja (Rosseto et al, 1997), o qual se diferencia apenas com relação a duração de cada fase. A primeira fase da embebição de sementes é puramente física, geralmente rápida e resulta no relativo equilíbrio do conteúdo de água, quando se inicia a fase II da embebição que é caracterizada por reduções da velocidade de hidratação e da intensidade respiratória (Marcos Filho, 2015).…”