Root morphology acclimation to phosphorus supply by six cultivars of Trifolium subterraneum L

Robert P. Jeffery, Richard J. Simpson, Hans Lambers, Daniel R. Kidd, Megan H. Ryan

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Aims: Trifolium subterraneum L. is the predominant annual pasture legume in southern Australia. Cultivars with improved phosphorus (P) foraging ability would improve the P-use efficiency of agricultural systems. We therefore investigated variation in root traits related to P-uptake among six cultivars. Methods: Micro-swards were grown at six levels of P in field soil with indigenous arbuscular mycorrhizal (AM) fungi for six weeks. Dry matter yield, tissue P concentration, rhizosphere carboxylates, AM fungal colonisation and root morphological traits were measured. Results: The cultivars showed similar shoot and root yield responses to P supply. Average root diameter did not change, specific root length (SRL) increased and root tissue density (RTD) decreased with increased P supply. Amounts of total rhizosphere carboxylates were low (<1.2 nmol cm−1 root). The percentage of root length colonised by AM fungi was greatest (29–43 %) at an intermediate level (8 mg kg−1 dry soil) of P supply. Conclusions: Most differences among cultivars were reasonably consistent across P supply levels, indicating greater numbers of lines could be screened reliably at a single P level. Low colonisation by AM fungi at low P supply deserves consideration when selecting soils for cultivar comparisons. Increased SRL and decreased RTD at high P supply likely result from self-shading within the micro-swards and warrant further investigation.

Original languageEnglish
Pages (from-to)21-34
Number of pages14
JournalPlant and Soil
Volume412
Issue number1-2
DOIs
Publication statusPublished - 1 Mar 2017

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