MT08021 - N, P and K Deficiency Diagnosis in and Consequences for Ptilotus Nobilis Production

This project focussed on the macronutrition of the comparatively new garden, landscape and cut flower native Australian species, Ptilotus nobilis (commonly known as mulla mulla). Ptilotus species are increasing in popularity due to their distinctive flower forms and colours, but not much is known about the nutritional requirements to grow them successfully. This project addresses this knowledge gap by studying the nutritional requirements of two Outback Princess series Ptilotus nobilis cultivars, Passion and Purity. A key outcome of this project is that nitrogen deficiency can occur comparatively readily, but the symptoms expressed vary for different varieties: Passion shows pale green leaves, whilst Purity develops red leaf tips or margins. The roles of potassium and phosphorus are not so critical to the successful growing of Ptilotus. The project highlighted that by maintaining a regular supply of nitrogen to the plants, plant losses following pruning to remove spent flowers can be reduced. The significance of this to industry is that Ptilotus losses in production, after cutting back, in the garden and landscape can be significantly reduced. The impact of these findings will be seen in the near future as there are several forms of Ptilotus likely to be introduced to the marketplace in the coming years. Future R & D could focus on the nutritional requirements of other related, and comparatively new, colourful betalain-pigmented Australian native plant species. Understanding the key nutritional requirements of these species will assist in successfully cultivating future varieties. Many of these species are drought hardy and have comparatively low maintenance. As water use is becoming a more prominent issue, betalain-pigmented plants illustrate that you can have flower colour in the garden and landscape even during periods of drought aesthetically pleasing but also providing diversity of flora.