Non-structural carbohydrate metabolism and postharvest conservation of gerbera flowers

Abstract

The species Gerbera jamesonii Adlam has great economic importance in the ornamental sector, due to exuberance of floral stems. However, florists face some challenges such as postharvest handling and difficulty of conservation. Therefore, this study aimed to characterize the non-structural carbohydrate content in different floral stages of G. jamesonii var. Dawn and evaluate the effect of preservative solutions during the postharvest storage of this species. For this purpose, it was quantified TSS, RS and NRS from the seven stages of gerbera stems ontogeny (E1, E2, E3, E4, E5, E6 and E7). The preservative solutions used were: T1) distilled water; T2) citric acid (100 mg L -1 ); T3) glucose (20 g L -1); T4) gibberellic acid (GA 3 , 5 mg L -1 ); T5) calcium chloride (CaCl 2 , 20g L -1 ) and T6) Sodium Thiosulphate (STS, 20 mM). The effect of preservative solutions were assessed daily, considering the longevity of flowers, variation in the absorption of preservative solution, pH of the solution and fresh mass variation. The experimental design was completely randomized with four replicates. There was a difference in carbohydrate metabolism during floral opening and senescence. In the orange bracts there was a lower TSS content, while in the inflorescences it was observed a reduction in the yellowish, greenish-green and greenish stages. The content of RS increased in the bracts, whereas in the inflorescence there was no difference. The NRS content was higher in the orange bracts, showing lower rates in the inflorescences in yellowish and yellowish greenish stages. The preservative solutions had an impact, on the floral stem longevity, varying according to the solutions used, i.e. CaCl 2 and STS reduced the durability of gerbera flower in 9.25 and 11.5 days, respectively, compared to stems kept in distilled water. The glucose solution did not promote a significant difference compared to water. Therefore, we conclude that there is variation in the metabolism of non-structural carbohydrates during the floral development of G. jamesonii var. Dawn and the tested solutions were not effective in promoting postharvest conservation of gerbera. Keywords: Gerbera jamesonii, sugars, floral stem, preservative solutions. RESUMO Metabolismo de carboidratos não estruturais e conservação pós-colheita de gérberaA espécie Gerbera jamesonii Adlam tem grande importância econômica no setor ornamental, devido à exuberância das hastes florais. Contudo, os floricultores enfrentam alguns entraves como o manuseio pós-colheita e a dificuldade de conservação. Assim, este trabalho teve como objetivo caracterizar o metabolismo de carboidratos não estruturais das hastes florais de G. jamesonii var. Dawn e avaliar o efeito de soluções conservantes ao longo do armazenamento pós-colheita. Para este propósito, quantificou-se o teor de açúcar solúvel total (AST), açúcar redutor (AR) e açúcar não redutor (ANR) de brácteas e inflorescências de gérbera, classificadas em sete estádios (E1, E2, E3, E4, E5, E6 e E7). As soluções conservantes usadas fo...

Postharvest physiology of cut flowers

“…Studies on changes in carbohydrate compounds in cut flowers demonstrated strong regulation of sucrose and starch metabolism during floral development. Santos et al (2016) and Alves et al (2017) observed variations in the metabolism of nonstructural carbohydrates during floral opening and senescence of Lilium pumilum and Gerbera jamesonii, exhibiting great mobilization of compounds, which are used in the production of energy demanded by the floral development.…”