Variation in morphological and physiological parameters in herbaceous perennial legumes in response to phosphorus supply

Abstract

Change in morphological and physiological parameters in response to phosphorus (P) supply was studied in 11 perennial herbaceous legume species, six Australian native (Lotus australis, Cullen australasicum, Kennedia prorepens, K. prostrata, Glycine canescens, C. tenax) and five exotic species (Medicago sativa, Lotononis bainesii, Bituminaria bituminosa var albomarginata, Lotus corniculatus, Macroptilium bracteatum). We aimed to identify mechanisms for P acquisition from soil. Plants were grown in sterilised washed river sand; eight levels of P as KH 2 PO 4 ranging from 0 to 384 μg P g −1 soil were applied. Plant growth under low-P conditions strongly correlated with physiological P-use efficiency and/ or P-uptake efficiency. Taking all species together, at 6 μg P g −1 soil there was a good correlation between P uptake and both root surface area and total root length. All species had higher amounts of carboxylates in the rhizosphere under a low level of P application. Six of the 11 species increased the fraction of rhizosphere citrate in response to low P, which was accompanied by a reduction in malonate, except L. corniculatus. In addition, species showed different plasticity in response to P-application levels and different strategies in response to P deficiency. Our results show that many of the 11 species have prospects for low-input agroecosystems based on their high P-uptake and P-use efficiency.

Public-domain software for root image analysis

“…This measurement is associated with the root diameter; thinner roots contribute to higher surface area values and form the exchange site between plant and soil for water and nutrient absorption (Waisel & Eshel, 2002). Its determination is important because some studies reported changes in root surface area related to nutrient availability in soil (Desnos, 2008;Pang et al, 2010;Mei et al, 2011). The root surface area can be calculated from data of root length and volume.…”

Citrate and malonate increase microbial activity and alter microbial community composition in uncontaminated and diesel-contaminated soil microcosms

“…Soil acidification poses a potential impediment to biodegradation as PHCs are optimally degraded within a near-neutral pH (Dibble and Bartha, 1979). However, carboxylate exudation in plants has only been weakly correlated to rhizosphere acidification (Pang et al, 2010;Pearse et al, 2006), thus highlighting one of the limitations of applying model systems to real rhizospheres and underlining the need for future in situ studies with high carboxylate exuding plants.…”

“…Contamination of soils by petroleum hydrocarbons (PHCs) can impair soil function and pose serious risks to human and ecosystem health (Park and Park, 2011;Ramadass et al, 2015). A novel approach for remediating surface soils contaminated with PHCs is to grow plants in order to benefit from their stimulating effect on rhizosphere microorganisms (bioremediation) (Anderson et al, 1993;Ma et al, 2010).…”

“…It should also be noted that while many studies have investigated the role of carboxylates in plant nutrient acquisition and aluminium detoxification (Pang et al, 2010;Pearse et al, 2006;Shane and Lambers, 2005), the impact of carboxylates on the soil microbial community has received considerably less attention. Additionally, whilst studies have examined the microbial biodegradation of carboxylates in contrasting soil types (Fujii et al, 2010(Fujii et al, , 2012Hashimoto, 2007;Jones and Darrah, 1994), soil horizons (Evans, 1998;van Hees et al, 2002) and with variations in the initial pH of the organic acid applied (Ström et al, 2005), as far as we are aware, there are no studies examining in detail the biodegradation of carboxylates, and their effect on the microbial community, in soils contaminated with PHCs.…”

Interactive effects of phosphorus deficiency and exogenous auxin on root morphological and physiological traits in white lupin (Lupinus albus L.)

“…Plant responses to low P availability are associated with increased resource allocation to roots [8,9], which leads to increased root:shoot ratios and enhanced P acquisition [10,11]. Roots also exhibit morphological responses to low P availability, such as increases in specific root length [12], root hair density and elongation [13,14], and LR formation and elongation [15]. These plastic root responses increase the surface area to volume ratio [16] and enable plants to capture P from P-limited environments or P-rich patches in otherwise P-deficient soils [17][18][19].…”