Comparison of mineral requirements of some cultivars in two proteaceae genera

We previously reported that nutrition of the Proteaceae is complex and not completely understood. Factors affecting nutrition include climate, quality of soils (fertility, pH, texture), and species. Soilless cultivation with a closed cycle watering system allowed us to clarify some factors, like fertilization balance and water requirements, of species like Protea eximia and Protea cynaroides. An EC contract recently gave us the opportunity to study the mineral and water needs of seven cultivars of the Proteaceae: from the genus Protea: 'Niobe', 'Snow Queen', 'Pink Velvet', 'Sheila' and T 96 06 01, and from the genus Leucospermum: 'Succession II' and 'High Gold'. We can confirm large differences in mineral requirements between cultivars belonging to the same genus, but we observed largest differences between the two genera. Furthermore, although members of the Proteaceae are generally adapted to dry conditions, adequate water remains a major factor for good plant growth. Presently we can confirm that specific nutritional regimes for each species and cultivar are not necessary; the nutrient supplies must meet integrated requirements of the plant's growth stage, flowering period, pruning and season.