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Phosphorus is critical for plant growth but often becomes less accessible due to its precipitation with cations in soil. Fabaceae, a diverse plant family, exhibits robust adaptability and includes species like Lupinus albus, known for its efficient phosphorus utilization via cluster roots. Here, we systematically identified phosphorus-utilization-efficiency (PUE) gene families across 35 Fabaceae species, highlighting significant gene amplification in PUE pathways in Fabaceae. Different PUE pathways exhibited variable amplification, evolution, and retention patterns among various Fabaceae crops. Additionally, the number of homologous genes of the root hair development gene RSL2 in L. albus was far more than that in other Fabaceae species. Multiple copies of the RSL2 gene were amplified and retained in L. albus after whole genome triplication. The gene structure and motifs specifically retained in L. albus were different from homologous genes in other plants. Combining transcriptome analysis under low-phosphorus treatment, it was found that most of the homologous genes of RSL2 in L. albus showed high expression in the cluster roots, suggesting that the RSL2 gene family plays an important role in the adaptation process of L. albus to low-phosphorus environments and the formation of cluster roots. [ABSTRACT FROM AUTHOR]

Organic phosphorus (OP) is an essential component of the soil P cycle, which contributes to barley nutrition after its mineralization into inorganic phosphorus (Pi). However, the dynamics of OP utilization in the barley rhizosphere remain unclear. In this study, phytin was screened out from six OP carriers, which could reflect the difference in OP utilization between a P-inefficient genotype Baudin and a P-efficient genotype CN4027. The phosphorus utilization efficiency (PUE), root morphological traits, and expression of genes associated with P utilization were assessed under P deficiency or phytin treatments. P deficiency resulted in a greater root surface area and thicker roots. In barley fed with phytin as a P carrier, the APase activities of CN4027 were 2–3-fold lower than those of Baudin, while the phytase activities of CN4027 were 2–3-fold higher than those of Baudin. The PUE in CN4027 was mainly enhanced by activating phytase to improve the root absorption and utilization of Pi resulting from OP mineralization, while the PUE in Baudin was mainly enhanced by activating APase to improve the shoot reuse capacity. A phosphate transporter gene HvPHT1;8 regulated P transport from the roots to the shoots, while a purple acid phosphatase (PAP) family gene HvPAPhy_b contributed to the reuse of P in barley. [ABSTRACT FROM AUTHOR]

The experiment was to explore the relationship between phosphorus supply and growth, photosynthesis and phosphorus uptake and utilization of millet. Jizajinmiao 1 and Jigu 39 millet varieties were used as test materials. Three phosphorus supply levels (0, 75 and 150 mg/kg) were set through greenhouse pot experiment. The results showed that under the same phosphorus supply level, the plant height, leaf area index, shoot dry weight, plant biomass, chlorophyll content, net photosynthetic rate and transpiration rate of Jigu 39 were significantly higher than that of Jizajinmiao 1 (P<0.05), and the root length and root shoot ratio were significantly lower than that of Jizajinmiao 1 (P<0.05). Under different phosphorus supply levels, plant height, shoot dry weight, whole plant biomass, chlorophyll content, chlorophyll and net photosynthetic rate of millet varieties increased significantly with the increase of phosphorus supply concentration (P<0.05). The comparison of fitting parameters of light intensity-photosynthetic response curve showed that under the same phosphorus supply level, the apparent quantum efficiency of Jigu 39 was higher than the Jizajinmiao 1, and the two cultivars increased significantly with the increase of phosphorus concentration. At the same phosphorus supply level, the phosphorus uptake of Jigu 39 was significantly higher than that of Jizajinmiao 1 (P<0.05). With the increase of the phosphorus supply concentration, the phosphorus absorption of the two cultivars increased significantly (P<0.05). The experiment indicates that adding phosphorus nutrition during the jointing and heading stages can effectively improve the growth indicators and photosynthetic characteristics of millet, increase its phosphorus absorption, and promote the accumulation of dry matter quality. [ABSTRACT FROM AUTHOR]

The article discusses research which analyzed linkage between phosphorus-utilization efficiency (PUE) with stem biomass in rice. The study measured the variation in physico-morphological traits under hydroponic condition including relative soil-plant analysis development value, relative stem dry weight, relative shoot phosphorus concentration, relative shoot phosphorus uptake, shoot internal phosphorus remobilisation (SIPR), total plant IPR, relative shoot PUE and relative root diameter.

Arbuscular mycorrhizal fungi (AMF) provide benefits to host plants mainly by improving nutrition. In rice, as in other plants, AMF colonization is promoted under phosphorus (P) deficiency, and the symbiosis can lead to an improvement in P uptake and plant biomass. While there is economic potential for the fungi to substitute chemical fertilizers for sustainable rice production, the current dogma holds that their benefits are nullified when used in fertile soil. Here we show that inoculation of an AMF mixture in non-sterilized lowland paddy soil with high P availability increased the degree of fungal colonization and the development of arbuscular mycorrhizal structures in 'Chaew Khing' rice seedlings. The increase in AMF colonization was correlated with higher shoot growth in the AMF-inoculated plants. Analysis of plant nutrient status indicated that the AMF treatment caused a reduction in the total P and Fe concentrations in the shoot tissues and a reduction in the total N concentration in the root tissues of the mycorrhizal plants. Nevertheless, the enhanced mycorrhizal colonization led to an increase in P utilization efficiency as well as N:P and C:P ratios in the AMF-inoculated seedlings. These results indicate that, under high P supply, AMF can benefit the host plant by enhancing more efficient use of P, rather than improving its uptake. This work highlights the potential benefit of AMF inoculation for rice cultivation under high P availability. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Improving plant ability to acquire and efficiently utilize phosphorus (P) is a promising approach for developing sustainable pasture production. This study aimed to identify ryegrass cultivars with contrasting P use efficiency, and to assess their associated biochemical and molecular responses. Nine ryegrass cultivars were hydroponically grown under optimal (0.1 mM) or P-deficient (0.01 mM) conditions, and P uptake, dry biomass, phosphorus acquisition efficiency (PAE) and phosphorus utilization efficiency (PUE) were evaluated. Accordingly, two cultivars with high PAE but low PUE (Ansa and Stellar), and two cultivars with low PAE and high PUE (24Seven and Extreme) were selected to analyze the activity and gene expression of acid phosphatases (APases), as well as the transcript levels of P transporters. Our results showed that ryegrass cultivars with high PAE were mainly influenced by root-related responses, including the expression of genes codifying for the P transporter LpPHT1;4, purple acid phosphatase LpPAP1 and APase activity. Moreover, the traits that contributed greatly to enhanced PUE were the expression of LpPHT1;1/4 and LpPHO1;2, and the APase activity in shoots. These outcomes could be useful to evaluate and develop cultivars with high P-use efficiency, thus contributing to improve the management of P in grassland systems. [ABSTRACT FROM AUTHOR]

Organic phosphorus (OP) is an essential component of the soil P cycle, which contributes to barley nutrition after its mineralization into inorganic phosphorus (Pi). However, the dynamics of OP utilization in the barley rhizosphere remain unclear. In this study, phytin was screened out from six OP carriers, which could reflect the difference in OP utilization between a P-inefficient genotype Baudin and a P-efficient genotype CN4027. The phosphorus utilization efficiency (PUE), root morphological traits, and expression of genes associated with P utilization were assessed under P deficiency or phytin treatments. P deficiency resulted in a greater root surface area and thicker roots. In barley fed with phytin as a P carrier, the APase activities of CN4027 were 2–3-fold lower than those of Baudin, while the phytase activities of CN4027 were 2–3-fold higher than those of Baudin. The PUE in CN4027 was mainly enhanced by activating phytase to improve the root absorption and utilization of Pi resulting from OP mineralization, while the PUE in Baudin was mainly enhanced by activating APase to improve the shoot reuse capacity. A phosphate transporter gene HvPHT1;8 regulated P transport from the roots to the shoots, while a purple acid phosphatase (PAP) family gene HvPAPhy_b contributed to the reuse of P in barley.

Phosphorus (P) is a major limiting nutrient reducing crop yields especially in weathered soils of the subtropics and tropics. P exhibits poor mobility and availability to plants in soil. To overcome P deficiency in soil, phosphatic fertilizers are added. Global phosphate rock reserves are finite, and the addition of phosphatic fertilizers is not financially and ecologically sustainable. Mungbean (Vigna radiata (L.) Wilczek) is important grain legume for nutritional security. Attempts are being made to develop mungbean varieties with better P-use efficiency through enhanced P uptake and utilization. In the present study, 327 accessions of 18 Vigna species were examined for inter- and intra-specific variation for traits related to phosphorus uptake and utilization efficiency under hydroponic conditions at two levels of phosphorus. Significant species-specific variation was recorded for studied traits. Among the studied Vigna species, mungbean exhibited higher phosphorus use efficiency. Seven mungbean genotypes (IC 251950, IC 585931, V1002532AG, IC 371653, IC 331615, V1001400AG, and V1000532BG) were found to be promising for both PupE and PutiE. Using mean and standard deviation as criteria, mungbean genotypes identified with high phosphorus-use efficiency include IC 25950 and IC 583664. Mungbean genotypes KPS 1546, IC 277060, IC 697141, IC 343440, and Pusa 0831 were identified based on the stress tolerance index as genotypes that performed better under P stress. Cultivated species revealed higher PUE in comparison withwild forms. The most promising genotype identified from this study for PUE can be used as a parent for the development of a mapping population of mungbean for understanding genetics of PUE under a low-phosphorus environment. [ABSTRACT FROM AUTHOR]

The high phosphorus (P) acquisition ability of crops can reduce their dependence on artificial inorganic phosphate (Pi) supplementation under Pi-limited conditions. Melon (Cucumis melo L.) is vulnerable to Pi deficiency. This study was carried out to explore the morphological and physiological responses of melon to low-Pi stress under a hydroponic system. The results show that low-Pi stress significantly disturbed nutrient homeostasis, reduced P content, and resulted in iron accumulation in melon seedlings and brown iron plaque formation on the root surface. A nutrient pool of P and Fe formed on the roots to forage for more Pi under low-Pi conditions. Severe long-term low-Pi stress promoted primary root elongation and inhibited lateral root growth, which increased the longitudinal absorption zone of the roots. The decrease in P content of the roots upregulated the expression of the acid phosphatase (APase) gene and increased APase activity. The high-affinity phosphate transporter (Pht1) genes were also upregulated significantly. These morphological and physiological responses significantly increased Pi uptake rate and P utilization efficiency at the melon seedling stage. These findings will be useful for screening low-Pi-tolerant varieties and sustaining melon production in P-limited environments. [ABSTRACT FROM AUTHOR]

Phosphorus (P) limitation is a significant factor restricting crop production in agricultural systems, and enhancing the internal P utilization efficiency (PUE) of crops plays an important role in ensuring sustainable P use in agriculture. To better understand how P is remobilized to affect crop growth, we first screened P-efficient (B73 and GEMS50) and P-inefficient (Liao5114) maize genotypes at the same shoot P content, and then analyzed P pools and performed non-targeted metabolomic analyses to explore changes in cellular P fractions and metabolites in maize genotypes with contrasting PUE. We show that lipid P and nucleic acid P concentrations were significantly lower in lower leaves of P-efficient genotypes, and these P pools were remobilized to a major extent in P-efficient genotypes. Broad metabolic alterations were evident in leaves of P-efficient maize genotypes, particularly affecting products of phospholipid turnover and phosphorylated compounds, and the shikimate biosynthesis pathway. Taken together, our results suggest that P-efficient genotypes have a high capacity to remobilize lipid P and nucleic acid P and promote the shikimate pathway towards efficient P utilization in maize. [ABSTRACT FROM AUTHOR]

Improving plant ability to acquire and efficiently utilize phosphorus (P) is a promising approach for developing sustainable pasture production. This study aimed to identify ryegrass cultivars with contrasting P use efficiency, and to assess their associated biochemical and molecular responses. Nine ryegrass cultivars were hydroponically grown under optimal (0.1 mM) or P-deficient (0.01 mM) conditions, and P uptake, dry biomass, phosphorus acquisition efficiency (PAE) and phosphorus utilization efficiency (PUE) were evaluated. Accordingly, two cultivars with high PAE but low PUE (Ansa and Stellar), and two cultivars with low PAE and high PUE (24Seven and Extreme) were selected to analyze the activity and gene expression of acid phosphatases (APases), as well as the transcript levels of P transporters. Our results showed that ryegrass cultivars with high PAE were mainly influenced by root-related responses, including the expression of genes codifying for the P transporter LpPHT1;4, purple acid phosphatase LpPAP1 and APase activity. Moreover, the traits that contributed greatly to enhanced PUE were the expression of LpPHT1;1/4 and LpPHO1;2, and the APase activity in shoots. These outcomes could be useful to evaluate and develop cultivars with high P-use efficiency, thus contributing to improve the management of P in grassland systems.

Background Limitation of plant productivity by phosphorus (P) supply is widespread and will probably increase in the future. Relatively large amounts of P fertilizer are applied to sustain crop growth and development and to achieve high yields. However, with increasing P application, plant P efficiency generally declines, which results in greater losses of P to the environment with detrimental consequences for ecosystems. Scope A strategy for reducing P input and environmental losses while maintaining or increasing plant performance is the development of crops that take up P effectively from the soil (P acquisition efficiency) or promote productivity per unit of P taken up (P utilization efficiency). In this review, we describe current research on P metabolism and transport and its relevance for improving P utilization efficiency. Conclusions Enhanced P utilization efficiency can be achieved by optimal partitioning of cellular P and distributing P effectively between tissues, allowing maximum growth and biomass of harvestable plant parts. Knowledge of the mechanisms involved could help design and breed crops with greater P utilization efficiency. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is a major limiting nutrient reducing crop yields especially in weathered soils of the subtropics and tropics. P exhibits poor mobility and availability to plants in soil. To overcome P deficiency in soil, phosphatic fertilizers are added. Global phosphate rock reserves are finite, and the addition of phosphatic fertilizers is not financially and ecologically sustainable. Mungbean (Vigna radiata (L.) Wilczek) is important grain legume for nutritional security. Attempts are being made to develop mungbean varieties with better P-use efficiency through enhanced P uptake and utilization. In the present study, 327 accessions of 18 Vigna species were examined for inter- and intra-specific variation for traits related to phosphorus uptake and utilization efficiency under hydroponic conditions at two levels of phosphorus. Significant species-specific variation was recorded for studied traits. Among the studied Vigna species, mungbean exhibited higher phosphorus use efficiency. Seven mungbean genotypes (IC 251950, IC 585931, V1002532AG, IC 371653, IC 331615, V1001400AG, and V1000532BG) were found to be promising for both PupE and PutiE. Using mean and standard deviation as criteria, mungbean genotypes identified with high phosphorus-use efficiency include IC 25950 and IC 583664. Mungbean genotypes KPS 1546, IC 277060, IC 697141, IC 343440, and Pusa 0831 were identified based on the stress tolerance index as genotypes that performed better under P stress. Cultivated species revealed higher PUE in comparison withwild forms. The most promising genotype identified from this study for PUE can be used as a parent for the development of a mapping population of mungbean for understanding genetics of PUE under a low-phosphorus environment.

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high phosphorus (P) acquisition ability of crops can reduce their dependence on artificial inorganic phosphate (Pi) supplementation under Pi-limited conditions. Melon (Cucumis melo L.) is vulnerable to Pi deficiency. This study was carried out to explore the morphological and physiological responses of melon to low-Pi stress under a hydroponic system. The results show that low-Pi stress significantly disturbed nutrient homeostasis, reduced P content, and resulted in iron accumulation in melon seedlings and brown iron plaque formation on the root surface. A nutrient pool of P and Fe formed on the roots to forage for more Pi under low-Pi conditions. Severe long-term low-Pi stress promoted primary root elongation and inhibited lateral root growth, which increased the longitudinal absorption zone of the roots. The decrease in P content of the roots upregulated the expression of the acid phosphatase (APase) gene and increased APase activity. The high-affinity phosphate transporter (Pht1) genes were also upregulated significantly. These morphological and physiological responses significantly increased Pi uptake rate and P utilization efficiency at the melon seedling stage. These findings will be useful for screening low-Pi-tolerant varieties and sustaining melon production in P-limited environments.

Organic phosphorus (P) is an important component of the soil P pool, and it has been proven to be a potential source of P for plants. The phosphorus utilization efficiency (PUE) and PUE related traits (tiller number (TN), shoot dry weight (DW), and root dry weight) under different phytate-P conditions (low phytate-P, 0.05 mmol L−1 and normal phytate-P, 0.5 mmol L−1) were investigated using a population consisting of 128 recombinant inbred lines (RILs) at the vegetative stage in barley. The population was derived from a cross between a P-inefficient genotype (Baudin) and a P-efficient genotype (CN4027, a Hordeum spontaneum accession). A major locus (designated Qpue.sau-3H) conferring PUE was detected in shoots and roots from the RIL population. The quantitative trait locus (QTL) was mapped on chromosome 3H and the allele from CN4027 confers high PUE. This locus explained up to 30.3 and 28.4% of the phenotypic variance in shoots under low and normal phytate-P conditions, respectively. It also explains 28.3 and 30.7% of the phenotypic variation in root under the low and normal phytate-P conditions, respectively. Results from this study also showed that TN was not correlated with PUE, and a QTL controlling TN was detected on chromosome 5H. However, dry weight (DW) was significantly and positively correlated with PUE, and a QTL controlling DW was detected near the Qpue.sau-3H locus. Based on a covariance analysis, existing data indicated that, although DW may affect PUE, different genes at this locus are likely involved in controlling these two traits.

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phosphorus (P) is an important nutrient that can restrict plant growth. However, the influence of P deficiency on elemental homeostasis and application of the growth rate hypothesis in higher plants remain to be assessed.Two shrubs, Zygophyllum xanthoxylum and Nitraria tangutorum, were used as experiment material and subjected to five P addition treatments: 0, 17.5, 35.0, 52.5 and 70.0 mg P·kg−1 soil.The biomass and relative growth rate of Z. xanthoxylum did not change with altered P supply. There was no significant difference in P concentration among the treatments for Z. xanthoxylum, but N. tangutorum showed an upward trend. The P stoichiometric homeostasis of Z. xanthoxylum was higher than that of N. tangutorum. For Z. xanthoxylum, available P in the rhizosphere improved significantly under extreme P deficiency conditions, and P concentrations in all treatments were lower than in N. tangutorum, showing that Z. xanthoxylum had stronger P absorption and P utilization capacity.No relationships between growth rate and C:N:P ratios were found in Z. xanthoxylum. The strong P efficiency, and high and stable dry matter accumulation, are likely contributors in maintaining stoichiometric homeostasis. In addition, the relatively high biomass accumulation and high P utilization efficiency for Z. xanthoxylum does not support the growth rate hypothesis for this species. [ABSTRACT FROM AUTHOR]

Phosphorus fertilizer application depths are extremely important for increasing phosphorus uptake and utilization efficiencies. In the present study, root distribution, biomass, grain yield, phosphorus uptake and utilization efficiencies were determined in field experiment and soil column experiment, with five treatments including CK (no P applied), P5 (phosphorus application depth was 5 cm), P10 (phosphorus application depth was 10 cm), P15 (phosphorus application depth was 15 cm), and P20 (phosphorus application depth was 20 cm). Phosphorus fertilizer application depths significantly affected root dry weight and root length of summer maize with a trend of P15>P10>P20>P5>CK. Compared with P5 treatment, averaged grain yield of P15 treatment increased by 23.1% in two years, averaged root dry weight and total root length increased by 13.1% and 22.9% in two years. Both P15 and P20 treatments increased the proportion of root dry weight and root length in the soil layer below -20 cm. The proportion of root dry weight of P15 and P20 treatments reached 35.4% and 36.4%, and the proportion of root length reached 58.7% and 59.3% in soil column experiments; the proportion of root dry weight both reached 19.0% and the proportion of root length reached 39.8% and 39.9% in field experiment, respectively. The optimization of root distribution promoted the accumulation and transport of phosphorus in plants. Compared with P5 treatment, P10, P15, and P20 treatments increased the averaged phosphorus accumulation in two years by 10.6%, 25.2%, and 14.7%, the average phosphorus transport amount in two years by 46.9%, 76.6%, and 57.6%, and the grain yield by 12.9%, 23.1%, and 10.6%, respectively. Compared with P5 treatment, P15 treatment increased the averaged P partial factor productivity, P agronomic efficiency and P apparent utilization efficiency by 19.1 kg kg-1, 19.1 kg kg-1, and 25.2% in two years, respectively. In summary, deep fertilization of phosphorus could increase the distribution of root in deep soil layers, improve the absorption and utilization efficiencies of phosphorus in plants, and significantly improve the grain yield of summer maize. Under the condition of this study, the suitable P fertilizer application depth was 15 cm from the soil surface. [ABSTRACT FROM AUTHOR]

Aims: Plants can optimize the allocation of phosphorus (P) among their foliar P fractions to increase the P utilization efficiency (PUE). Identifying the genetic relationships between foliar P fractionation and PUE could provide opportunities to improve the P efficiency of barley (Hordeum vulgare L.). Methods: The differences in the concentrations and proportions of inorganic P, ester P, nucleic acid P and insoluble P between a wild barley cultivar CN4027 and a commercial cultivar Baudin were studied, and their quantitative trait loci (QTLs) at normal P (NP) and low P (LP) fertilisations were mapped. The PUE that was determined in the previous study was used to analyze the relationship between PUE and foliar P fractionation in this research. Results: Both cultivars of barley could increase their metabolic P fractions as an LP stress tolerance strategy to ensure their continued metabolic activities in response to LP stress. Cultivar CN4027 showed higher nucleic acid P concentration (NPC), nucleic acid P proportion (NPP) and insoluble P proportion (IPP) than cultivar Baudin under LP stress. This abundant organic P (Po) pool of CN4027 ensured the normal functioning of its metabolic pathways under LP stress. The close relationships between the foliar P fractionation and PUE could be explained by two QTL clusters, Cl-3H.02 and Cl-5H.01. The QTL cluster Cl-3H.02 is flanked by the markers bPb3256099-bPb3255630 on chromosome 3H and controls the ester P concentration (EPC), ester P proportion (EPP), insoluble P concentration (IPC) and IPP. Conclusions: The QTL cluster Cl-3H.02 might have great potential for the future genetic improvement of barley PUE and may offer clues for the genetic relationships between the foliar P fractionation and PUE. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency in soil is a major constrain for rice production. An important set of rice genotypes (landraces, old improved and new improved varieties) were screened for P deficiency tolerance in two major cropping seasons of Sri Lanka, in 2012. The Ultisol soil, which was collected from a plot cultivated with rice without fertilizer application for past 40 years (P0) at the Rice Research and Development Institute (RRDI), Bathalagoda, Sri Lanka, was used as the potting medium for greenhouse trials. Two field trials were conducted in the same plots at RRDI. Both P0 and P30 (30 mg/kg P2O5) conditions were used in the two greenhouse trials. At the early vegetative (three weeks after transplanting), late vegetative (six weeks after transplanting) and flowering stages, plant height and number of tillers per plant were recorded. At the flowering stage, shoots were harvested and shoot dry weight, shoot P concentration, shoot P uptake and P utilization efficiency were measured. All data were statistically analyzed using analysis of variance, regression and cluster procedures. The measured parameters were significantly different between P0 and P30 conditions (P < 0.05). Higher shoot dry weight was reported by the rice genotypes H4 and Marss under P0 conditions. The regression analysis between shoot dry weight and P utilization efficiency revealed that the studied rice genotypes could be categorized to three P deficiency tolerance classes. A total of 13 genotypes could be considered as highly tolerant and 4 genotypes as sensitive for P deficiency. These results could be used to select parental genotypes for breeding and genetic studies and also to select interesting varieties or landraces for organic rice production.

In nature, crops such as soybean are concurrently exposed to temperature (T) stress and phosphorus (P) deficiency. However, there is a lack of reports regarding soybean response to T × P interaction. To fill in this knowledge-gap, soybean was grown at four daily mean T of 22, 26, 30, and 34°C (moderately low, optimum, moderately high, and high temperature, respectively) each under sufficient (0.5 mM) and deficient (0.08 mM) P nutrition for the entire season. Phosphorus deficiency exacerbated the low temperature stress, with further restrictions on growth and net photosynthesis. For P deficient soybean at above optimum temperature (OT) regimes, growth, and photosynthesis was maintained at levels close to those of P sufficient plants, despite a lower tissue P concentration. P deficiency consistently decreased plant tissue P concentration ≈55% across temperatures while increasing intrinsic P utilization efficiency of canopy photosynthesis up to 147%, indicating a better utilization of tissue P. Warmer than OTs delayed the time to anthesis by 8–14 days and pod development similarly across P levels. However, biomass partitioning to pods was greater under P deficiency. There were significant T × P interactions for traits such as plant growth rates, total leaf area, biomass partitioning, and dry matter production, which resulted a distinct T response of soybean growth between sufficient and deficient P nutrition. Under sufficient P level, both lower and higher than optimum T tended to decrease total dry matter production and canopy photosynthesis. However, under P-deficient condition, this decrease was primarily observed at the low T. Thus, warmer than optimum T of this study appeared to compensate for decreases in soybean canopy photosynthesis and dry matter accumulation resulting from P deficiency. However, warmer than OT appeared to adversely affect reproductive structures, such as pod development, across P fertilization. This occurred despite adaptations, especially the increased P utilization efficiency and biomass partitioning to pods, shown by soybean under P deficiency.

Induction and secretion of acid phosphatases (APases) is considered to be an important strategy for improving plant growth under conditions of low inorganic phosphate (Pi). Purple acid phosphatases (PAPs), are an important class of plant APases that could be secreted into the rhizosphere to utilize organic phosphorus (Po) for plant growth and development. To date, only a few members of the PAP family have been identified in soybean. In this paper, we identified a secreted PAP in soybean, GmPAP14, and investigated its role in utilizing external phytate, the main form of organic phosphorus in the soil. An analysis of its expression and promoter showed that GmPAP14 was mainly expressed in the root and was strongly induced following Po treatment, during which its expression expanded from meristematic to maturation zones and root hairs. In vitro enzyme assays indicated that GmPAP14 had a relatively high phytase activity. Furthermore, GmPAP14 overexpression increased secreted APase activities and phytase activities, leading to the improved use of external plant phytate, higher phosphorus content, and increased shoot weight. Thus, these results confirmed that GmPAP14 is an important gene induced in response to Po, and that it predominantly participates in utilizing external Po to enhance plant growth and development.

Soil compaction interferes in soil nutrient transport and root growth. The aim of this work was to evaluate eucalypt growth and phosphorus (P) nutritional efficiency as affected by soil compaction and P rates. The treatments were composed of a 3 × 4 factorial scheme (soil bulk densities levels versus P fertilization rates) for two weathered tropical soils, a clayey Ferralsol (FClayey) and a sandy Ferralsol (FSandy). The soil bulk densities assessed were 0.90, 1.10 and 1.30 g cm−3 for FClayey, and 1.35, 1.55 and 1.75 g cm−3 for FSandy. The P rates were 0, 150, 300 and 600 mg kg−1 for FClayey, and 0, 100, 200 and 400 mg kg−1 for FSandy. Soil compaction reduced root growth, P content in the plant, P utilization efficiency and P recovery efficiency; and increased average root diameter. Phosphorus fertilization increased root length density, root surface area, dry matter, P content in the plant, P utilization efficiency and P uptake efficiency; and decreased P recovery efficiency. It was concluded that P fertilization is not effective to offset the deleterious effects of soil compaction on eucalypt growth and nutrition. Abbreviations: FClayey: clayey Ferralsol; FSandy: sandy Ferralsol; RDens: root length density; RDiam: root diameter; RSurf: root surface area; RDM: root dry matter; SDM: shoot dry matter; WPDM: whole-plant dry matter; RP: root P content; SP: shoot P content; WPP: whole-plant P content; PUtE: P utilization efficiency; PUpE: P uptake efficiency; PRE: P recovery efficiency. [ABSTRACT FROM AUTHOR]

Phosphorus (P) efficiency includes both P acquisition efficiency (PAE) and internal P utilization efficiency (PUE). Despite substantial research, genotypic variation in PAE and PUE remains incompletely understood in the field. A 2-year field study was conducted to compare PAE and PUE and related morphological, physiological, and molecular root traits of two winter wheat cultivars (Triticum aestivum L. cv. SJZ8 and KN92) in response to six P application rates in a P-deficient calcareous soil. Both cultivars showed similar growth and yield potential at each P supply level, reaching optimal growth at the same P application rate of about 100 kg P ha-1. However, the two cultivars differed in how they achieved yield and P efficiency. As P supply increased for both cultivars, root dry weight (RDW), root length density, and expression of the phosphate transporter gene TaPHT1.2 in roots initially increased and then stabilized, but arbuscular mycorrhizal fungal colonization, rhizosphere acid phosphatase activity, expressions of the P-starvation marker gene TaIPS1.1 and the purple acid phosphatase gene TaPAP16 in roots initially decreased and then stabilized. To enhance P acquisition when the P supply was deficient, KN92 modified the morphology of its roots, while SJZ8 increased the physiological activities in its roots. With an adequate P supply, high expression of TaPHT1.2 in roots might account for efficient P uptake for both cultivars, especially for KN92. Although P uptake per RDW was similar for both cultivars at anthesis, PAE was higher for KN92 than SJZ8 in terms of total P uptake in aboveground parts, whereas shoot and grain PUE were higher in SJZ8 than in KN92, mainly during the reproductive growth stage. These results indicate that P efficiency is under genotypic control at all P supply levels tested in both wheat cultivars, and that the two cultivars depend on different root strategies for P acquisition and utilization in response to changes in the P supply. [ABSTRACT FROM AUTHOR]

In nature, crops such as soybean are concurrently exposed to temperature (T) stress and phosphorus (P) deficiency. However, there is a lack of reports regarding soybean response to T × P interaction. To fill in this knowledge-gap, soybean was grown at four daily mean T of 22, 26, 30, and 34°C (moderately low, optimum, moderately high, and high temperature, respectively) each under sufficient (0.5 mM) and deficient (0.08 mM) P nutrition for the entire season. Phosphorus deficiency exacerbated the low temperature stress, with further restrictions on growth and net photosynthesis. For P deficient soybean at above optimum temperature (OT) regimes, growth, and photosynthesis was maintained at levels close to those of P sufficient plants, despite a lower tissue P concentration. P deficiency consistently decreased plant tissue P concentration ≈55% across temperatures while increasing intrinsic P utilization efficiency of canopy photosynthesis up to 147%, indicating a better utilization of tissue P. Warmer than OTs delayed the time to anthesis by 8–14 days and pod development similarly across P levels. However, biomass partitioning to pods was greater under P deficiency. There were significant T × P interactions for traits such as plant growth rates, total leaf area, biomass partitioning, and dry matter production, which resulted a distinct T response of soybean growth between sufficient and deficient P nutrition. Under sufficient P level, both lower and higher than optimum T tended to decrease total dry matter production and canopy photosynthesis. However, under P-deficient condition, this decrease was primarily observed at the low T. Thus, warmer than optimum T of this study appeared to compensate for decreases in soybean canopy photosynthesis and dry matter accumulation resulting from P deficiency. However, warmer than OT appeared to adversely affect reproductive structures, such as pod development, across P fertilization. This occurred despite adaptations, especially the increased P utilization efficiency and biomass partitioning to pods, shown by soybean under P deficiency. [ABSTRACT FROM AUTHOR]

Induction and secretion of acid phosphatases (APases) is considered to be an important strategy for improving plant growth under conditions of low inorganic phosphate (Pi). Purple acid phosphatases (PAPs), are an important class of plant APases that could be secreted into the rhizosphere to utilize organic phosphorus (Po) for plant growth and development. To date, only a few members of the PAP family have been identified in soybean. In this paper, we identified a secreted PAP in soybean, GmPAP14, and investigated its role in utilizing external phytate, the main form of organic phosphorus in the soil. An analysis of its expression and promoter showed that GmPAP14 was mainly expressed in the root and was strongly induced following Po treatment, during which its expression expanded from meristematic to maturation zones and root hairs. In vitro enzyme assays indicated that GmPAP14 had a relatively high phytase activity. Furthermore, GmPAP14 overexpression increased secreted APase activities and phytase activities, leading to the improved use of external plant phytate, higher phosphorus content, and increased shoot weight. Thus, these results confirmed that GmPAP14 is an important gene induced in response to Po, and that it predominantly participates in utilizing external Po to enhance plant growth and development. [ABSTRACT FROM AUTHOR]

Phosphorus (P) nutrition is indispensable for plant growth and development. Seven wheat varieties (Sarsabz, Kiran-95, Khirman, NIA-Amber, NIA-Sunhari, NIA-Sunder and NIA-Saarang) were evaluated for their growth response to P deficient (0.02 mM) and adequate (0.20 mM) levels in hydroponic culture. A factorial combination of treatments, repeated four times, was arranged in a completely randomized design. Wheat varieties differed significantly (P< 0.01) in shoot and root dry matter production, root: shoot ratio, shoot and root P concentration and uptake, and shoot P utilization efficiency. Shoot P uptake and utilization efficiency were strongly correlated (r = 0.89, r = 0.77) with shoot dry matter production. On the basis of shoot dry matter production and P utilization efficiency, cultivars were grouped into four categories. NIA-Sunder, Sarsabz and Kiran-95 were efficient as well as responsive (ER) genotypes. Khirman, NIA-Sunhari, NIA-Saarang and NIA-Amber were categorized as non-efficient and non-responsive (NENR) genotypes. Prevalence of such genetic variations among these wheat cultivars can be useful in developing P- efficient genotypes.

Low phosphorus (P) availability is a major constraint for cotton production. Consequently, P-efficient genotypes can improve productivity under conditions where the higher application of P is not economical. This study was conducted to characterize cotton genotypes for P-use efficiency under various P concentrations (0, 10, 20, 40, 80, and 500 μM KH2PO4). The results showed large genotypic variation in five selected traits, such as root dry weight, shoot dry weight, photosynthetic activity, P-utilization efficiency, and P-uptake efficiency. Based on these five selected traits, the genotypes were grouped into three main classes as efficient, moderate efficient, and inefficient genotypes as proposed by different researchers. Most of the genotypes behaved in a similar pattern under different P concentrations. Among the genotypes, Xinluzao-49 and Xinluzao-48 were considered as P efficient while CCRI-64 and Yumian-21 as inefficient genotypes. However, the rest of the genotypes were considered as moderately P efficient. The results prove that a large genetic potential exists in cotton genotypes for P-use efficiency, and the use of P-efficient genotypes for cultivation will reduce the application of phosphatic fertilizers. Furthermore, the use of P-efficient genotypes will improve cotton breeding activities and help in improving the environmental sustainability of cotton production.

The objective of this experiment was to explore the variability of response to phosphorus (P) availability in three fodder Poaceae species native of saline biotopes,Aeluropus littoralis, Catapodium rigidum, andHordeum maritimum. The behavior of these wild species has been compared to that of a cultivated one,Hordeum vulgare. Plants were grown in plastic pots filled with inert sand. The experiment was carried out in a greenhouse with six P levels: 0, 5, 15, 60, 180, and 360 µM P concentration supplied as KH2PO4. Results showed that the growth of the four species is strongly affected by the low phosphorus availability in the medium. Furthermore, to reach 80% of their maximum yield expressed as shoot dry weight (DW), a soil phosphorus concentration of approximately 40 µM P concentration is sufficient forHordeum maritimum, whereas approximately 66, 120, and 132 µM P concentration are needed forC. rigidum, A. littoralis, andHordeum vulgareplants, respectively. Thus, our results showed that spontaneous species are more tolerant to P deficiency than cultivated barley. The relative performance of the three wild Poaceae species is likely related to their capacity to maintain higher P acquisition efficiency (PAE) under low P concentration conditions. These native Poaceae species may therefore represent genetic resources for the improvement of barley. [ABSTRACT FROM PUBLISHER]

Genetic variation in phosphorus utilization efficiency (PUE) widely exists among wheat genotypes. However, the underlying mechanisms are still unclear. Two contrasting wheat genotypes, Heng4399 (H4399) and Tanmai98 (TM98), were screened out from 17 bread wheat genotypes based on shoot soluble phosphate (Pi) concentrations. The TM98 had a significantly higher PUE than the H4399, especially under Pi deficiency. The induction of genes in the PHR1-centered Pi signaling pathway was significantly higher in TM98 than in H4399. Collectively, through a label-free quantitative proteomic analysis, 2110 high-confidence proteins were identified in shoots of the two wheat genotypes. Among them, 244 and 133 proteins were differentially accumulated under Pi deficiency in H4399 and TM98, respectively. The abundance of proteins related to nitrogen and phosphorus metabolic processes, small molecule metabolic process, and carboxylic acid metabolic process weas significantly affected by Pi deficiency in the shoots of the two genotypes. The abundance of proteins in energy metabolism, especially photosynthesis, was decreased by Pi deficiency in the shoots of H4399. Inversely, the PUE-efficient genotype TM98 could maintain protein abundance in energy metabolism. Moreover, the proteins involved in pyruvate metabolism, glutathione metabolism, and sulfolipid biosynthesis were significantly accumulated in TM98, which probably contributed to its high PUE. Improving the PUE of wheat is urgent and crucial for sustainable agriculture. Genetic variation among wheat genotypes provides materials for exploring the underlying mechanisms for high PUE. This study selected two wheat genotypes with contrasting PUE to reveal the differences in the physiological and proteomic responses to phosphate deficiency. The PUE-efficiency genotype TM98 greatly induced the expression of genes in the PHR1-centered Pi signaling pathway. Subsequently, the TM98 could maintain the abundance of proteins related to energy metabolism and enhance the abundance of proteins involved in pyruvate metabolism, glutathione metabolism, and sulfolipid biosynthesis to increase PUE under Pi deficiency. The differentially expressed genes or proteins between the genotypes with contrasting PUE would provide potential and basis for breeding wheat varieties with improved phosphorus use efficiency. [Display omitted] • The wheat genotype TM98 has a higher PUE than the genotype TM98 under Pi deficiency. • High PUE correlates with enhanced induction of genes in the Pi signaling pathway. • The genotypes with contrasting PUE showed opposing responses in glutathione metabolism. • The abundance of proteins in sulfolipid and galactolipid biosynthesis was enhanced. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency in soil is a major constrain for rice production. An important set of rice genotypes (landraces, old improved and new improved varieties) were screened for P deficiency tolerance in two major cropping seasons of Sri Lanka, in 2012. The Ultisol soil, which was collected from a plot cultivated with rice without fertilizer application for past 40 years (P 0 ) at the Rice Research and Development Institute (RRDI), Bathalagoda, Sri Lanka, was used as the potting medium for greenhouse trials. Two field trials were conducted in the same plots at RRDI. Both P 0 and P 30 (30 mg/kg P 2 O 5 ) conditions were used in the two greenhouse trials. At the early vegetative (three weeks after transplanting), late vegetative (six weeks after transplanting) and flowering stages, plant height and number of tillers per plant were recorded. At the flowering stage, shoots were harvested and shoot dry weight, shoot P concentration, shoot P uptake and P utilization efficiency were measured. All data were statistically analyzed using analysis of variance, regression and cluster procedures. The measured parameters were significantly different between P 0 and P 30 conditions ( P < 0.05). Higher shoot dry weight was reported by the rice genotypes H4 and Marss under P 0 conditions. The regression analysis between shoot dry weight and P utilization efficiency revealed that the studied rice genotypes could be categorized to three P deficiency tolerance classes. A total of 13 genotypes could be considered as highly tolerant and 4 genotypes as sensitive for P deficiency. These results could be used to select parental genotypes for breeding and genetic studies and also to select interesting varieties or landraces for organic rice production. [ABSTRACT FROM AUTHOR]

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Phosphorus (P) is a finite natural resource and is essential for food production. The amount of P involved in food production in China relative to the increase of food production has increased dramatically over the past decades, which has led to serious environmental pollution. Because of China's enormous share in global P fertilizer production (30%) and consumption (37.5%), it evidently plays a crucial role in developing a more sustainable use of this essential resource for agriculture. We performed an integrated analysis of the P flows, P stocks, P utilization efficiencies (PUE) and environmental implications at the national level in China for the year 2010, complemented with an analysis at regional, county and farm levels. The static Material Flow Analysis approach based on the law of mass balance was used. We found that P accumulation in the arable land and P losses in the livestock raising industry are the major contributors to environmental pollution. Improving the PUE in arable land and the livestock raising industry, on the basis of the actual demands combined with efforts to promote the use of residual soil P on arable land and the recycling of organic manure and wastes, will significantly reduce the consumption and losses of P from the food chain, and will slow down the depletion of this finite natural resource. [ABSTRACT FROM AUTHOR]

The objectives of the current study were to identify the genetic material, which is characterized by a high growth rate and maximum root system size; to study the variability of Russian and foreign rice varieties for the markers associated with the genes, which determine efficient phosphorus utilization; to assess the possibility of using the simple sequence repeat (SSR) markers discussed in the current work for the introgression of the previously mapped genes; and to subdivide the donor samples identified in the Russian gene pool into groups characterized by a high probability of resistance development via different genetic mechanisms. The features which determine the intensity of the phosphorus uptake and their inheritance in rice varieties are discussed. We have studied the variability of the 72 rice varieties of Russian and foreign origin for the development rate of the root system and its size at maturity. The highest development rate of the root system was observed for the following varieties: Liman, Arborio, Dalnevostochnyi, Selenio, Oceano, Atlant, Musa, Fontan, Cerere, Sharm, Serpentine, Khankaiskii 52, Leader, Boyarin, and Druzhnyi. The samples of Russian origin were characterized by a higher growth rate than the Italian ones. The root weight at the stage of maturation varied from 1.5 to 4.5 g in different rice varieties, the maximum root weight being observed in the following varieties: Carnise, Rapan, Onix, and G-57. The root length varied from 17 to 26 cm with the highest length being displayed by the D 25-2, G 75-5, Ryzhik, G-52, Krepysh, and Snezhinka varieties. The variability observed in the Russian and foreign varieties for all the examined SSR loci associated with the genes controlling the phosphorus uptake showed that marker assistant selection may be carried out for this feature in the gene pool under study. The maximum allele number was detected for the RM 247 marker, localized on chromosome 12. [ABSTRACT FROM AUTHOR]

It has been almost 25 years since the first report of the gene encoding a high-affinity phosphate transporter (PT), PHO84 , in yeast. Since then, an increasing number of yeast PHO84 homologs as well as other genes encoding proteins with phosphate (Pi) transport activities have been identified and functionally characterized in diverse plant species. Great progress has been made also in deciphering the molecular mechanism underlying the regulation of the abundance and/or activity of these genes and their products. The regulatory genes affect plant Pi homeostasis commonly through direct or indirect regulation of the abundance of PTs at different levels. However, little has been achieved in the use of PTs for developing genetically modified crops with high phosphorus use efficiency (PUE). This might be a consequence of overemphasizing Pi uptake from the rhizosphere and lack of knowledge about the roles of PTs in Pi transport and recycling within the plant that are required to optimize PUE. Here, we mainly focused on the genes encoding proteins with Pi transport activities and the emerging understanding of their regulation at the transcriptional, post-transcriptional, translational, and post-translational levels. In addition, we propose potential strategies for effective use of PTs in improving plant growth and development. [ABSTRACT FROM AUTHOR]

Phosphate (Pi) remobilization in plants is critical to continuous growth and development. AtATL80 is a plasma membrane (PM)-localized RING E3 ubiquitin (Ub) ligase that belongs to the Arabidopsis Tóxicos en Levadura (ATL) family. AtATL80 was upregulated by long-term low Pi (0–0.02 mM KH 2 PO 4 ) conditions in Arabidopsis seedlings. AtATL80 -overexpressing transgenic Arabidopsis plants ( 35S:AtATL80-sGFP ) displayed increased phosphorus (P) accumulation in the shoots and lower biomass, as well as reduced P-utilization efficiency (PUE) under high Pi (1 mM KH 2 PO 4 ) conditions compared to wild-type plants. The loss-of-function atatl80 mutant line exhibited opposite phenotypic traits. The atatl80 mutant line bolted earlier than wild-type plants, whereas AtATL80 -overexpressors bloomed significantly later and produced lower seed yields than wild-type plants under high Pi conditions. Thus, AtATL80 is negatively correlated not only with P content and PUE, but also with biomass and seed yield in Arabidopsis . In addition, AtATL80 -overexpressors were significantly more sensitive to cold stress than wild-type plants, while the atatl80 mutant line exhibited an increased tolerance to cold stress. Taken together, our results suggest that AtATL80, a PM-localized ATL-type RING E3 Ub ligase, participates in the Pi mobilization and cold stress response as a negative factor in Arabidopsis . [ABSTRACT FROM AUTHOR]

Field experiments of winter wheat-summer maize rotation were conducted in North China Plain irrigation area to explore the effects of wheat season irrigation with dairy effluent on grain yield, phosphorus uptake, accumulative phosphorus usage efficiency and phosphorus accumulation in soil. The results showed that the irrigation with dairy effluent significantly improved the yields of winter wheat and summer maize. With the increasing of P2O5 carried by dairy effluent into soil, winter wheat yield increased at first and then decreased. When the P2O5 increased 137 kg·hm-2, winter wheat yield increased to the maximum (7646.4 kg·hm-2) and the phosphorus utilization rate was the highest (24.8%). But excessive phosphorus decreased the winter wheat yield and phosphorus utilization efficiency. Summer maize yield and phosphorus uptake increased with the increase of P2O5 carried by dairy effluent. The summer maize yield increased by 2222.4-2628.6 kg·hm-2 and the phosphorus uptake increased by 13.9–21.1 kg·hm-2 in contrast to the control (CK). Under conventional phosphorus fertilization at 88 kg·hm-2, and the summer maize yield increased by 2235.0 kg·hm-2 compared with CK. As the time of irrigation with dairy effluent increasing, the grain yield increased more significantly. The cumulative phosphorus utilization in this rotation system increased year by year. After six seasons of crop harvest, the cumulative phosphorus utilization rate increased into 40.0%–47.7%. Under the experimental condition, two times of irrigation with the dairy effluents in the winter wheat-summer maize rotation system was the best operating mode. [ABSTRACT FROM AUTHOR]

Pearl millet [ Pennisetum glaucum (L.) R. Br] production on the acid sandy Sahelian soils in West Africa (WA) is severely limited by low plant-available phosphorus (P) in addition to erratic rainfall. We sought to examine the genetic variability for P uptake and P utilization efficiency in 180 WA pearl millet inbred lines or subsets thereof under low (LP) and high P (HP) conditions in one field and two pot experiments, determine the relationships among the measured traits and grain yield under field conditions at three other independent WA sites, and identify potential secondary selection traits for improving grain yield under LP. We observed genetic variation for P uptake and utilization in both seedling and mature plants. P utilization efficiency increased under LP conditions. Total P uptake was more important for grain production than P utilization under LP field conditions ( r = 0.57*** vs r = 0.30***). The estimated response to indirect selection was positive for most of the measured morphological and P-efficiency parameters. We conclude that both seedling and mature plant traits are potentially useful as secondary traits in selection of pearl millet for low-P adaptation. These results should be validated using heterozygous pearl millet genetic materials. Ultimately, pearl millet breeding activities for low P tolerance in WA should be integrated with other system-oriented research such as nutrient cycling, intercropping or rotations with legumes, better crop-tree-livestock integration, and modest applications of locally available rock phosphate. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is patchily distributed in soil because of its slow diffusion, especially in soil with a high phosphate absorption coefficient (PAC). Root responses to localized supply of phosphate were studied in Sesbania cannabina grown in volcanic andosol, which has a high PAC. Seedlings were grown in soil that was supplied with 0, 10, 100, 500, or 1000 mg P kg-1. After 30 days, analyses of plant P and root morphological were conducted. Further rhizobox experiments were also conducted. Seedlings were grown with layered P sources or localized P patches. Densely branched lateral roots (DBLRs) developed only in the 10 and 100 mg P kg-1 treatments. Although an increase in shoot dry weight (DW) was observed in the 500 and 1000 mg P kg-1 treatments, DBLRs were not observed. The number of DBLRs was positively correlated with shoot DW, root DW, and number of nodules, and negatively correlated with phosphorus use efficiency of shoots and roots. The rhizobox experiment showed that most DBLRs were observed in the layer with added P and in the position where P fertilizer was present. DBLRs developed so as to monopolize the P fertilizer by completely enveloping the area around it. The results suggest that DBLR formation is one of S. cannabina's P acquisition strategies. [ABSTRACT FROM AUTHOR]