P uptake characteristics and root morphological responses in the mining ecotype of Polygonum hydropiper under high organic P media

ABSTRACT

Understanding plant phosphorus (P) assimilation and its root morphological responses is important to acquire an ideal material for remediation of P-enriched environments. Pot experiments were conducted to explore P accumulation and root morphological traits in a mining ecotype (ME) and non-mining ecotype (NME) of Polygonum hydropiper under different organic P (Po) sources (G1P, AMP, ATP, IHP) and inorganic P (Pi) source (KH₂PO₄), and also their responses to a high level of IHP for different growth periods. Both ecotypes showed higher biomass in Pi and IHP treatments than other Po sources. P accumulation in seedlings were in the order of Pi > IHP > other Po media. Extending the growth period increased biomass and P accumulation in both ecotypes. The ME demonstrated 1.11–1.46 times higher P accumulation than the NME. Seedlings fed with IHP demonstrated significantly greater morphological parameters of fine, medium, and thick roots compared to other Po sources. Total root length, surface area, and volume of both ecotypes significantly increased with the prolonged growth period. The ME has a higher ability to develop root system and exhibits better distribution of fine roots to enhance P accumulation from high P media, and thus it is a worthy material for P-phytoextraction.

KEYWORDS:

• Organic phosphorus (Po)
• phosphorus accumulation
• phytoremediation
• Polygonum hydropiper
• root morphology

Acknowledgments

The authors appreciate the critical reading and revising of the manuscript by Craig Stapleton and Guangdeng Chen.

Funding

This study is jointly supported by the grants from the National Natural Science Foundation (41271307), and the Sichuan Science and Technology Support Program (2013NZ0044), (2014NZ0008).