Leaf Blackening

Autor: Nicole E. Windell, Waafeka Vardien, Gerard Jacobs, E. W. Hoffman
Rok vydání: 2018
Předmět:
DOI: 10.1002/9781119431077.ch3
Popis: Most commercially important Protea species and cultivars are susceptible to a postharvest disorder, termed “leaf blackening,” in which the foliage can develop a discoloration during any point of the postharvest marketing chain. Leaf blackening significantly reduces product quality and vase life, and is often the main reason for consignment rejection. This serious disorder has major negative consequences for export to international, long-distance markets. A shift from air to sea freight is progressively favored within the international flower trade. Sea freight is by far the more cost-effective alternative, with the additional benefit of reducing the energy consumed during the transport of these luxury products. Whilst sea freight offers more precise control and maintenance of the cold chain, a significantly longer cold storage period is required, which enhances the probability for the onset and development of leaf blackening. In order to maintain product quality under long-term storage conditions to ensure an extended vase life, a better understanding of how and why this postharvest disorder manifests itself is imperative. Factors which may be of relevance in the development of leaf blackening, such as water stress, carbohydrate stress, high respiration rates, nectar production, light and possibly ethylene, are discussed. Progress in the development of strategies to control leaf blackening is reviewed and include: girdling beneath the inflorescence; carbohydrate pulsing; ethanol pulsing; rapid cooling immediately after harvesting; and storage under controlled atmosphere. The latter technology, along with dynamic controlled atmosphere (DCA) and initial low oxygen stress (ILOS) warrants further investigation. Currently, approaches to reduce leaf blackening may vary widely between species and cultivars and with cultural practices, as each is prone to its own incidence of the disorder. As such, future research will need to be focused on a finer scale, such as the genetic level using an approach such as RNA-sequencing technology. An understanding of the genetic basis of the postharvest disorder may provide greater insight into the physiological processes and may better equip producers with finding alternate strategies to combat leaf blackening.
Databáze: OpenAIRE
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