A range of Proteaceous shrubs and other nursery plants were grown in containers with soilless media and various N levels. Plants demonstrated a range of responsiveness. Supplying soilless media with Osmocote (26% N) and other short term fertilisers proved to be a satisfactory method of studying the comparative nutrition of a wide range of container grown nursery plants using factorial experiments incorporating N, P, K and lime. Nutrient response surfaces were obtained using a central composite incomplete block design. Most Proteaceous shrubs were intolerant of high P levels due to excessive luxury consumption resulting in toxic foliar nutrient levels, especially in the presence of high N. Phosphorus sensitivity in plants appeared to correspond with the soil nutrient levels in their native habitat. This applied to species studied in the 2 main sub-families in the Proteaceae while similar findings were indicated for other Australian genera. A range of optimum N requirements in the Proteaceae was found – lowest needs for Protea which also had the greatest tolerance of very low fertiliser additions, compared to Grevillea robusta with much higher N requirements and strong foliage growth inhibition if nutrient levels are very low. Proteoid root growth on Grevillea rosmarinifolia only occurred at low nutrient levels and was not required for satisfactory foliage growth of container grown plants. Pot plants and seedlings, especially tomato, responded strongly to N and often there were positive NK interactions influencing foliage growth. Lime requirements were studied and in erica increasing lime rates depressed foliage growth. Comparative nutrition studies indicate that general or broad spectrum container media may be unsuitable for some groups of nursery plants and that they could be replaced by potting mixes designed to meet the widely differing needs of the species often grown. The number of specialist mixes would depend on the range of plants and be governed by management considerations.
| Identifer | oai:union.ndltd.org:ADTP/283807 |
| Date | January 1979 |
| Creators | Thomas, M. B. |
| Publisher | Lincoln College, University of Canterbury |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://purl.org/net/lulib/thesisrights |
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