Protea Nutritional Problems and Soil Nutrient Status in Norton-Darwendale and Juliasdale Farming Areas, Zimbabwe

ABSTRACT

A study was conducted from November 2000 to February 2001 to establish causes of poor protea plant growth in the Juliasdale and Norton-Darwendale commercial farming areas of Zimbabwe. Soil and leaf samples from farmer-perceived “deficient” and “normal” areas were analyzed. Soils perceived by farmers to be deficient had lower levels of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) compared with the normal soils. In Juliasdale, all cultivars from perceived-deficient samples had lower levels of zinc (Zn) in leaves compared with normal leaves. Leucospermum cultivar ‘Tango’ and Protea cultivar ‘Moonshine’ also had low levels of P and Zn in the deficient plants compared with the normal plants. In Norton-Darwendale, the Protea cultivar ‘Moonshine’ had lower levels of nitrogen (N), P, K, and boron (B) in perceived-deficient samples compared with normal samples. Soil-analysis data were generally comparable to leaf-analysis data, indicating the potential use of leaf analysis to determine nutritional requirements of proteas.

Keywords:

• protea
• nutrient disorders
• foliar and soil analysis
• Zimbabwe

ACKNOWLEDGMENTS

Financial support from the European Union, under contract ERBCT970174 on “Research Crop Production of Proteaceae to Improve the Product Quality Traded in the International Ornamental Industry,” is gratefully acknowledged. The researchers are also grateful to the Zimbabwe Protea Association farmers for their assistance with the project.

Notes

^†Standard deviation.

^‡Soil brought to field capacity then aerobically incubated for 14 d at 35°C (16).