Putting the P in Ptilotus: a phosphorus-accumulating herb native to Australia

Area of Science:

• Plant physiology
• Agricultural science
• Ecology

Background:

• Ptilotus polystachyus (green mulla mulla) is a perennial herb native to Australian arid regions.
• It grows in nutrient-poor soils and shows potential for domestication.
• Its nutrient requirements, particularly phosphorus (P) and nitrogen (N), are not well understood.

Purpose of the Study:

• To compare the growth and nutrient accumulation of Ptilotus polystachyus and Cichorium intybus ('Puna') under varying phosphorus and nitrogen conditions.
• To assess the potential of Ptilotus polystachyus for domestication by examining its response to nutrient availability.

Main Methods:

• A controlled experiment using nutrient-deficient soil was conducted.
• Pots were amended with seven different rates of phosphorus (0-300 mg P pot(-1)) and nitrogen (0-270 mg N pot(-1)).
• Growth, P, and N accumulation were measured for both species.

Main Results:

• Ptilotus exhibited significantly greater shoot dry weights than chicory at low phosphorus levels (0, 15, 30 mg P pot(-1)).
• Ptilotus demonstrated high tolerance to phosphorus toxicity, showing no adverse effects at the highest P addition rate, unlike chicory.
• Both species showed similar responses to nitrogen addition.

Conclusions:

• Ptilotus polystachyus possesses a remarkable ability to thrive in both low and high phosphorus availability conditions, outperforming Cichorium intybus.
• Further research into the mechanisms of phosphorus uptake and tolerance in Ptilotus is recommended for its domestication potential.