TIME OF PRUNING AFFECTS YIELD, FLOWERING TIME AND FLOWER QUALITY OF PROTEA 'PINK ICE'

Abstract

Most Protea cultivars grown commercially in South Africa, flower outside the lucrative September to January period, when prices and demand for proteas on the European markets are high. Previous work established that the flowering period of certain Protea cultivars could be shifted to more favourable marketing periods through timing of pruning. To establish whether this is true for Protea 'Pink Ice', four-year-old plants were pruned at monthly intervals for the period January to December 1999. The highest yield was achieved for plants pruned in June and July, although flowering occurred within the unfavourable marketing window of February to May. However, when plants were pruned in March, the majority of flowering shoots were harvested during the high price period of December and January. Flowers borne on an autumn flush required 4 to 6 weeks longer to complete their development than for spring flush borne flowers. However, as flowers on the autumn flush are initiated 12 weeks prior to those on the spring flush, this implies that they are still able to complete their development about 6 weeks before those on the spring flush. This difference accounts for the ability of autumn initiated flowers (pruned in March), to peak earlier. The management of Protea 'Pink Ice' in a biennial pruning system was executed on a commercial scale, to verify that the June treatment does indeed result in the highest number of harvestable stems, 24 months after pruning. It was found that the June treatment gave the best income per plant, due to a higher number of harvestable stems although in an unfavourable marketing window. The phasing of production resulting from a June pruning in a biennial cropping system fitted this cultivar the best. Orchards should be divided into two blocks with one in the 'on year' and one in the 'off year' of biennial cropping.