THE INFLUENCE OF TEMPERATURE ON THE RESPIRATION RATE AND BROWNING OF PROTEA NERRIIFOLIA R BR INFLORESCENCES

The undesired discolouration of leaves of several Protea spp. is an obstacle in the marketing of good quality protea cutflowers. Browning was induced in leaves of P. neriifolia kept at high temperatures (60 and 65 °C) for relatively short periods (30 min). The browning was even more pronounced, and occurred at a lower temperature (40 °C) when the leaves were kept in closed plastic bags. A rise in temperature caused an increase in the rate of respiration of the leaves, which was dramatic at 65 °C. When determining the rate of respiration, it was found to differ greatly, from one part of the protea inflorescence to another. There was also a marked difference between the respiration rates of the florets in different positions on the protea inflorescence (centre or periphery). Such differences were also noted when comparing the rate of respiration of florets from inflorescences cut at different stages of development (closed bud through to fully open). The change in the rate of respiration of the florets after harvest of the inflorescences, showed a typical climacteric pattern. The importance of these findings with regard to the post-harvest handling of protea inflorescences will be discussed.