Non-structural carbohydrate metabolism and postharvest conservation of gerbera flowers

Ana Maria Oliveira Souza Alves,Jaianne Francielle Oliveira Santos Pimentel,Gustavo Ferreira Da Silva,Nilbe Carla Mapeli,Ana Maria Mapeli

doi:10.14295/oh.v23i3.1079

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 (GA3 , 5 mg L-1); T5) calcium chloride (CaCl2 , 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. CaCl2 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.

Highlights

The Brazilian floriculture has acquired remarkable values in the last years, characterizing itself as one of the most promising agribusiness segments
It is noted that the main cause of senescence of cut flowers is the loss of energy and water, which are necessary for the maintenance of vital processes (BRACKMANN et al, 2004)
In order to supply the floral stem metabolism, carbohydrates are translocated from the leaves to the tissues of the petals, mainly sucrose, which will be reduced by hydrolysis by the action of invertases and sucrose synthase, releasing glucose and fructose, that promote an increase in the concentration of solutes in the flowers and, reduction of the water potential, favoring the absorption of the solution (TAIZ and ZEIGER, 2013)

Summary

Introduction

The Brazilian floriculture has acquired remarkable values in the last years, characterizing itself as one of the most promising agribusiness segments. In this scenario, Gerbera jamesonii Adlam, known as gerbera, plays an important role (GUERRERO et al, 2012), being the fourth cut flower most commercialized in the domestic market and second most exported by Brazil (JUNQUEIRA and PEETZ, 2008), with uses in event decoration and floral arrangements (LUDWIG et al, 2010). The postharvest durability of the flowers is a result of physiological changes and depends on the amount of reserves, especially carbohydrates, as well as on other factors that may negatively influence, including occurrence of bacteria and fungi, physical injury to tissues and excessive loss of water. In order to supply the floral stem metabolism, carbohydrates are translocated from the leaves to the tissues of the petals, mainly sucrose (non-reducing sugar), which will be reduced by hydrolysis by the action of invertases and sucrose synthase, releasing glucose and fructose, that promote an increase in the concentration of solutes in the flowers and, reduction of the water potential, favoring the absorption of the solution (TAIZ and ZEIGER, 2013)

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Conclusion