Silber, A., Institute of Soils, Water Environ. Sci., Volcani C., Bet Dagan, Israel
Ganmore-Neumann, R., Institute of Soils, Water Environ. Sci., Volcani C., Bet Dagan, Israel
Ben-Jaacov, J., Dept. of Ornamental Horticulture, The Volcani Center, P.O. Box 6, Bet Dagan, Israel

The objective of this study was to compare the growth of three Leucadendrons (Proteaceae) cultivars ('Safari Sunset', 'Orot' and 'Meir') fertigated with three levels of P. The plants were grown in tuff (pyroclastic material, characterized by high porosity) in 101 pots and fertigated daily. The experiment included control treatment (plants irrigated with tap water) and three levels of P (0, 10 and 20 mg l-1), while N and K in the P-treatments were kept at a constant rate of 50 mg l-1. Under P deficiency, the development of 'Orot' plants was significantly superior to that of 'Safari Sunset' and 'Meir' cultivars, but as P application increased to 20 mg l-1, 'Safari Sunset' growth was quite similar to that of 'Orot'. The very low growth rate of 'Meir', probably eliminates this cultivar as a potential rootstock for commercial purpose. The low sensitivity of 'Orot' to nutrient application is a promising characteristic to avoid micro-nutrients deficiency and a significant advantage, especially under field conditions. No symptoms of P toxicity were observed even at the highest P level (20 mg l-1), at any of the cultivars tested. (C) 2000 Elsevier Science B.V.