Yield responses of mulla mulla (Ptilotus exaltatus Nees.) seedlings to additions of nitrogen, potassium and phosphorus fertiliser

Abstract

Native plants are increasingly being grown in Western Australia to produce flowers for export and the nutritional requirement of some of these species is not known. The nitrogen, phosphorus and potassium requirements for optimum growth of seedlings of one such species, Ptilotus exaltatus Nees., were measured in the glasshouse experiment reported here. There was a significant (P<0.05) growth response to nitrogen fertilisers over the range 20–80 mg N/kg soil. At all amounts of phosphorus and potassium, except for the nil-phosphorus treatments, the largest amount of applied nitrogen (80 mg N/kg soil) gave the maximum dry weight of shoots. The dry weight of shoots increased with the addition of phosphorus fertiliser up to 40 mg P/kg soil, particularly with 60 mg potassium and 80 mg N/kg soil. The addition of 160 mg P/kg soil and 120 mg K/kg soil depressed shoot growth at 80 mg N/kg soil. Potassium fertiliser increased plant growth at amounts up to about 60 mg K/kg soil. At the seedling stage of growth, critical concentration in shoots for deficiency was about 1.5% for potassium, and 0.9% for phosphorus. Adequate concentrations in shoots were about 1.7–2.7% for potassium, and 1.0–1.6% for phosphorus.

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

“…Several studies support our finding that Ptilotus species are able to both grow well on soil with low bicarbonate-extractable P and respond well to addition of P in spite of poor downregulation of P uptake when P is plentiful (e.g. Brennan et al, 2000). Islam et al (1999) examined a subtropical, semiarid Australian grassland on soil with low P availability, dominated in winter by forbs from the Amaranthaceae (P. exaltatus, P. macrocephalus, P. aerovoides), Chenopodiaceae and Malvaceae.…”

Mechanisms for tolerance of very high tissue phosphorus concentrations in Ptilotus polystachyus

“…Ptilotus polystachyus has previously been reported to grow well both at very low and very high P supply in soil (Islam et al 1999;Brennan et al 2000;Ryan et al 2009;Suriyagoda et al 2012). The present paper reports on the mechanism of high P tolerance in P. polystachyus using plants grown in hydropnics in order to ensure that the plants did indeed experience high P levels.…”

“…F. Muell. is a nonmycorrhizal Stewart et al 1993), Australian native perennial herb, which has an impressive ability to grow when P is abundant (Islam et al 1999;Brennan et al 2000;Ryan et al 2009;Suriyagoda et al 2012). For most species, P toxicity is observed when leaf (shoot) P is in the range of 5-42 mg P g −1 dry matter (DM) (Bhatti & Loneragan 1970;Loneragan et al 1982;Pang et al 2010b), and most either show P-toxicity symptoms or down-regulate their P-uptake capacity such that concentrations above 20 mg P g −1 DM are never reached (Shane & Lambers 2006;Shane et al 2008).…”

Stable isotope characteristics across narrow savanna/woodland ecotones in Wolfe Creek Meteorite Crater, Western Australia

“…7c). Ptilotus exaltatus, which was found in the central pan, in addition to being favored under high light intensity (Kadner 1998), is promoted in fertilized areas (Brennan et al 2000). Cows grazed within the WCMC up until it became a National Park.…”