Study of Phosphorus Acquisition Ability in Medicinal Plants of Salvia virgata, Achillea millefolium and Ziziphora clinopodioides Lam in Low Phosphorus Soils

Most of medicinal plants are able to grow in low P supply as well. In order to study the ability of some medicinal plant species، a greenhouse experiment was conducted with Salvia virgata، Achillea millefolium and Ziziphora clinopodioides Lam in a low P soil. The experiment was undertaken with three levels of P (0، 15، 150 mg kg-1)، two harvests and three replications as a randomized complete block design. In the second harvest and low P treatment، all species showed a high relative shoot dry matter (above 80%) which indicated a high P use efficiency of them. The range of shoot P concentration in low P treatment at the first harvest was between 0. 23% and 0. 29%. In this case، no significant difference was observed among different P treatments. In addition، the shoot P content of plants was almost high. As a result، all three plant species were P uptake efficient plants. The P influx in Ziziphora clinopodioides Lam was more than two other plant species. The results of the root- shoot ratio of plants at low P supplied was indicated that high P uptake efficiency of Salvia virgata was mostly due to its extensive root system، whilst، for Ziziphora clinopodioides Lam it was mostly due to its high P influx.