Involucral Bract Browning in Proteas - the What, How and What Now?

摘要

Involucral bract browning in Protea is characterised by brown blemishes that develop pre-harvest on the tips and/or margins of the involucral bracts, resembling a dirty nail, hence the common term of "dirty nail syndrome". These blemishes can occur onall sides of the inflorescence, or can be concentrated on the most sun-exposed side. Bract browning can seriously reduce the market value and export potential of this niche cut flower product, as it has a strong impact on the inflorescence appearance. Despite the visual and financial impact these blemishes can have on pack out rates at the producer level, bract browning in Protea has not been characterised yet, with no classification system for bract browning within South African export regulations, which currently only account for general blemishes. The aim of the study was to characterize bract browning in Protea 'Pink Ice' by using the South African export blemish quality standards as well as an adaptation of the classification system developed forTelopea species using three zones, on a 0-6 illustrative rating scale. Acceptability was determined for local market standards by benchmarking with a packing facility. Characterization of bract browning is required to assist the industry to assess the severity of involucral bract browning and to develop new strategies to prevent and/or ameliorate the development of bract browning in order to deliver premium quality products to a highly competitive international market.