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Wheat represents a fundamental component of the diet that contributes to ensuring global food security. However, its cultivation faces various abiotic and biotic constraints that result in fluctuating yields. The use of plant growth promoting rhizobacteria (PGPR) with the ability to solubilize phosphate presents itself as an environmentally friendly solution aimed to at enhancing sustainable agriculture practices. The objective of the present study is to assess the potential of PGPR in augmenting both yield and phosphorus (P) levels in wheat plants (Triticum durum L). under semi-controlled environmental conditions. Initially, the strains under investigation were screened for their capacity to dissolve different forms of mineral complex P, along with other plant growth promoting attributes such as iron chelation, Indole acetic acid (IAA) production, nitrogen fixation, and production of exopolysaccharides. Plant response to inoculation with PGPR was studied through an experiment conducted in a greenhouse involving four distinct treatments: (1) Control plants without any inoculation, (2) Inoculation with the PGP27 strain (Rahnella aquatilis), (3) Inoculation with the PGP25 strain (Erwinia persicina), and (4) Inoculation with the PGP374 strain (Raoultella terrigena). Results demonstrated that the studied strains exhibited significant promoting activities, including the solubilization of complex phosphate, the production of exopolysaccharides, IAA, siderophores, and atmospheric nitrogen fixation. Furthermore, the inoculation of plants with PGPR led to an increase in both biomass and plant phosphate concentrations, surpassing those observed in the control group. In conclusion, the findings propose that species like Raoultella and Erwinia have the potential to offer agronomic advantages as rhizobacteria that promote plant growth. [ABSTRACT FROM AUTHOR]

Tall wheatgrass is cultivated for pasture in marginal areas around the world due to its tolerance to abiotic stress including seasonal droughts and floods, as well as saline and alkaline soils. However, there is concern about its biomass productivity, which often does not exceed that of natural pastures. In this work we hypothesize that tall wheatgrass is a plant more sensitive to low P availability than commonly assumed. A glasshouse sand culture experiment was conducted to analyze morpho-physiological responses of tall wheatgrass to different P availability levels: 1 µmol L−1 phosphorus (severe deficiency, P1), 10 µmol L−1 phosphorus (representative value of soil solution in the region, P10) and 500 µmol L−1 phosphorus (full P supply, P500). Our results show that both limiting P conditions strongly decreased plant development and biomass accumulation, and altered above- and below-ground morphology, in comparison with P500 plants. The latter, in turn, had relative growth rate values comparable to those of other cultivated grasses under non-limiting conditions. In both P-deficient treatments, plant development was severely delayed starting from leaf number 3, even when P concentration in the pseudostem at early stages was similar or even higher than that of P500 plants. Our results suggest that developmental inhibition of tall wheatgrass at low P supply may be the consequence of a specific plant response to P concentration in soil solution, rather than to direct P starvation in plant tissues, and underlines the need of improvement of this species to enhance productivity in this environment. [ABSTRACT FROM AUTHOR]

Increasingly frequent and severe droughts pose significant threats to forest ecosystems, particularly affecting photosynthesis, a crucial physiological process for plant growth and biomass production. This study investigates the impact of phosphorus fertilization on the photosynthesis of common beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl.). In a common garden experiment, saplings originating from two provenances (wetter KA and drier SB provenances) were exposed to regular watering and drought in interaction with moderate and high phosphorus concentrations in the growing substrate. Results indicated that drought significantly reduced pre-dawn leaf water potential (ΨPD), net photosynthesis (Anet), stomatal conductance (gs) and photosynthetic performance index (PIabs) in both species. Phosphorus fertilization had a negative impact on Anet and PIabs, thus exacerbating the negative impact of drought on photosynthetic efficiency, potentially due to excessive phosphorus absorption by saplings. Provenance differences were notable, with the KA provenance showing better drought resilience. This research highlights the complexity of nutrient–drought interactions and underscores the need for cautious application of fertilization strategies in reforestation efforts under changing climatic conditions. [ABSTRACT FROM AUTHOR]

Application of coal fly ash (CFA) as a soil amendment has produced great agronomic benefits. However, there are potential risks of using CFA for soil amelioration, due to the abundance of some elements, both essential and non-essential in plants, which can cause phytotoxicity and it even may cause health problems for humans through the food chain. A pot experiment was conducted to investigate the effects of various CFA application rates (5%, 10%, 20%, 40%, and 80%) on plant growth, accumulation of essential nutrient elements and potentially toxic trace elements in erect milkvetch grown on a loess soil. The results showed that plant growth was significantly enhanced by the 5%, 10%, and 20% CFA treatments, while a CFA application rate ≥ 40% did not benefit plant growth, or even considerably inhibited plant growth. Plant phosphorus nutrition was improved by CFA application, but concentrations of potassium, copper, and zinc in plants declined when CFA was applied. Concentrations of molybdenum, boron, and selenium in plants generally increased with CFA application rate. A 5% CFA application rate is appropriate for the loess soil, a higher rate will cause phytotoxicity in erect milkvetch. CFA is a promising source of nutrients such as phosphorus, rational application of CFA to soil can enhance plant growth and improve plant phosphorus nutrition. [ABSTRACT FROM AUTHOR]

Increasingly frequent and severe droughts pose significant threats to forest ecosystems, particularly affecting photosynthesis, a crucial physiological process for plant growth and biomass production. This study investigates the impact of phosphorus fertilization on the photosynthesis of common beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl.). In a common garden experiment, saplings originating from two provenances (wetter KA and drier SB provenances) were exposed to regular watering and drought in interaction with moderate and high phosphorus concentrations in the growing substrate. Results indicated that drought significantly reduced pre-dawn leaf water potential (ΨPD), net photosynthesis (Anet), stomatal conductance (gs) and photosynthetic performance index (PIabs) in both species. Phosphorus fertilization had a negative impact on Anet and PIabs, thus exacerbating the negative impact of drought on photosynthetic efficiency, potentially due to excessive phosphorus absorption by saplings. Provenance differences were notable, with the KA provenance showing better drought resilience. This research highlights the complexity of nutrient–drought interactions and underscores the need for cautious application of fertilization strategies in reforestation efforts under changing climatic conditions.

Summary: Glutamate decarboxylase (GAD) is a Ca2+‐calmodulin‐activated, cytosolic enzyme that produces γ‐aminobutyrate (GABA) as the committed step of the GABA shunt. This pathway bypasses the 2‐oxoglutarate to succinate reactions of the tricarboxylic acid (TCA) cycle. GABA also accumulates during many plant stresses.We tested the hypothesis that AtGAD1 (At5G17330) facilitates Arabidopsis acclimation to Pi deprivation. Quantitative RT‐PCR and immunoblotting revealed that AtGAD1 transcript and protein expression is primarily root‐specific, but inducible at lower levels in shoots of Pi‐deprived (−Pi) plants.Pi deprivation reduced levels of the 2‐oxoglutarate dehydrogenase (2‐OGDH) cofactor thiamine diphosphate (ThDP) in shoots and roots by > 50%. Growth of −Pi atgad1 T‐DNA mutants was significantly attenuated relative to wild‐type plants. This was accompanied by: (i) an > 60% increase in shoot and root GABA levels of −Pi wild‐type, but not atgad1 plants, and (ii) markedly elevated anthocyanin and reduced free and total Pi levels in leaves of −Pi atgad1 plants. Treatment with 10 mM GABA reversed the deleterious development of −Pi atgad1 plants.Our results indicate that AtGAD1 mediates GABA shunt upregulation during Pi deprivation. This bypass is hypothesized to circumvent ThDP‐limited 2‐OGDH activity to facilitate TCA cycle flux and respiration by −Pi Arabidopsis. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) have been reported to increase yield and phosphorus (P) uptake. However, it is still unclear how the common bean responds to mycorrhizal inoculation when there is a phosphate supply. This research focused on finding out how bean performance will be affected by mycorrhizal inoculation and increasing P dosages in order to reduce phosphate input. The study was conducted during the A 2021 cropping season in Kabare, while a split-plot design was used to compare two levels of inoculation and increasing phosphorus doses. Rhizophagus irregularis inoculation significantly improved mycorrhizal colonization, biomass, yield, and harvest index of beans at 0 and 30 kg P ha-1. Bean plants inoculated with R. irregularis performed better in terms of biomass, yield, and harvest index at 30 kg P ha-1 than non-inoculated and inoculated plants at 60 and 120 kg P ha-1, indicating the potential of AMF in lowering phosphate input. Phosphorus levels of 60 and 120 kg P ha-1 significantly decreased mycorrhizal infection, indicating the impact of inorganic P on the mycorrhizal symbiosis. In the ferralitic soils of Kashusha, mycorrhizal inoculation with R. irregularis may be a key tool for increasing bean production and ensuring phosphate fertilizer savings.

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.)

Context: Banana production in Australia is in three primary sub-regions within tropical North Queensland and the industry faces a variety of challenges including costs of production, disease and pests, and environmental impacts. The range of soil characteristics and banana leaf nutrient status on banana farms has not previously been systematically described. This knowledge gap makes it difficult to adapt research, management recommendations, and regulations to the needs of the three primary growing sub-regions. Aims: In this work, we aimed to identify key soil factors that differentiate growing sub-regions, and provide context for future research and industry regulation. Methods: We characterised soil and banana leaf samples from 28 banana farms on soil types accounting for >85% of Australia's banana production. Key results and conclusions: Variation in soil properties and leaf nutrient concentrations were driven largely by site- (principal component 1 in both cases) and management-related variables (principal component 2 in both cases). Management-related foliar nutrient concentrations did not differ between regions despite differences in the associated soil variables. The most important site characteristics appeared to be soil parent material and climate. The Mareeba sub-region has basaltic soils, low rainfall and temperature, whereas the other two sub-regions are hotter, wetter and have a variety of soil parent materials. Leaf nitrogen concentrations were mostly below the regulated limit for additional nitrogen fertiliser application. Implications: Our findings can facilitate sub-region-specific site selection for research, extension, and monitoring and more targeted regulation of banana production- and environment-related issues. Banana production in tropical Australia faces challenges including costs of production, disease and pests, and environmental impacts, but the range of variation in soil and banana nutrient status among farms has not been systematically described. We found soil and leaf nutrition vary between growing sub-regions due to soil formation but this is not considered in regulation. Our findings could facilitate efficient research, extension, monitoring and regulation regarding banana production- and environment-related issues. [ABSTRACT FROM AUTHOR]

Abstract Maize (Zea mays L.) is an important staple food crop in sub-Saharan Africa (SSA) and contributes significantly to food security. Due to Striga, maize yield loss is estimated between 20 and 80% forcing some farmers to abandon their land therefore threatening food security. Many strategies have been applied to combat Striga infested fields to improve maize yields but alternative feasible approaches are still required. This study aimed at determining effects of phosphorus (P) and maize variety on Striga asiatica germination and attachment. A factorial experiment of eight P levels (0, 10, 20, 30, 40, 50, 60 and 70 kg ha−1), six maize varieties and Striga (inoculated and non-inoculated) in a 4 × 24 α-lattice design with three replications was set in a glasshouse at the University of Zimbabwe. A similar experiment was set under laboratory conditions using agar gel plates to determine S. asiatica germination using a complete randomized design with three replications. Adding P (at 40 kg ha−1) to soil infected with Striga, significantly (p

Reducing phosphate fertilizer inputs while increasing food nutritional quality has been posited as a major challenge to decrease human undernourishment and ensure food security. In this context, quinoa has emerged as a promising crop due to its ability to tolerate different stress conditions and grow in marginal soils with low nutrient content, in addition to the exceptional nutritional quality of its grains. However, there is scarce information about the phosphorus acquisition capacity of quinoa roots. This work aimed to provide new insights into P acquisition and functional root traits, such as root biomass, rhizosphere pH, carboxylate exudation, and acid phosphatase activity of thirty quinoa genotypes grown under P limiting conditions (7 mg P kg−1). Significant genotypic variation was observed among genotypes, with average P accumulation ranging from 1.2 to 11.8 mg. The shoot biomass production varied more than 14 times among genotypes and was correlated with the P accumulation on shoots (r = 0.91). Despite showing high variability in root traits, only root biomass production highly correlated with P acquisition (r = 0.77), suggesting that root growth/morphology rather than the measured biochemical activity possesses a critical role in the P nutrition of quinoa. [ABSTRACT FROM AUTHOR]

The main obstacles in obtaining consistently high and high-quality crops of Lens culinaris (L.) in Kazakhstan are the lack of moisture, low richness of soils with available elements of nutrients. The use of mineral fertilizers for Lens culinaris (L.) in the conditions of Northern Kazakhstan has not been studied yet. In our studies, the yield of different varieties of Lens culinaris (L.) in the dry-steppe zone has been estimated with different provision of soils with elements of nutrients for two years. Small-seeded varieties of Krapinka and Viceroy Lens culinaris (L.) were compared under various vegetation conditions, their responsiveness to growing conditions, the use of phosphorus fertilizers, yield and quality indicators. The results of the study showed that the lack of moisture during the vegetation period in 2019 negatively affected the yield of Lens culinaris (L.) and the effectiveness of the use of phosphate fertilizers, reduced the yield of both varieties by 6-8 times compared to 2018, up to 2-4 dt/ha. From the use of phosphorus fertilizers in doses of P120-150 with the content of available phosphorus 11-15 mg/kg under control, the yield of Lens culinaris (L.) of both varieties and the quality of products increased. It is noted that the variety of Viceroy Lens culinaris (L.) produced a higher yield than the variety of Krapinka Lens culinaris (L.). This is a biological feature of the variety and is confirmed by a large number of beans and seeds on natural and fertilized backgrounds. The trend of increasing yields and improving the quality indicators of products on fertilized backgrounds was in a favorable year and preserved in the dry season, which indicates the positive effect of improving the background of phosphorus nutrition. The studies have shown that Lens culinaris (L.) are very sensitive to moisture conditions. A favorable moisture-related year of receiving Krapinka - 5.6 dt/ha and Viceroy - 9.8 dt/ha brought in a good increase in the yield as a result of the use of phosphate fertilizers. During the research years, the optimal levels of provision of soil with available phosphorus for these varieties were in the range 25-30 mg/kg of soil. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga 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.)

Facing phosphate deficiency, phytoplankton use alkaline phosphatase (AP) to scavenge dissolved organophosphate (DOP). AP is a multitype (e.g., PhoA, PhoD) family of hydrolases and is known as a promiscuous enzyme with broad DOP substrate compatibility. Yet, whether the multiple types differentiate on substrates and collaborate to provide physiological flexibility remain elusive. Here we identify PhoA and PhoDs and document the functional differentiation between PhoA and a PhoD (PhoD_45757) in Phaeodactylum tricornutum. CRISPR/Cas9‐based mutations and physiological analyses reveal that (1) PhoA is a secreted enzyme and contributes the majority of total AP activity whereas PhoD_45757 is intracellular and contributes a minor fraction of the total AP activity, (2) AP gene expression compensates for each other after one is disrupted, (3) the DOP→PhoA→phosphate_uptake and the DOP_uptake→PhoD→phosphate pathways function interchangeably for some DOP substrates. These findings shed light on the underpinning of AP's multiformity and have important implications in phytoplankton phosphorus‐nutrient niche differentiation, physiological plasticity, and competitive strategy. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency affects plant yield and quality, yet at the same time, excessive phosphorus application does not necessarily promote the growth of plants. How to maintain a balance between biomass accumulation and phosphorus application is a problem. Therefore, the purpose of this research was to explore the relationship between yield and quality of Bupleurum and phosphorus fertilization, based on three phosphorus fertilization levels (20 kg∙ha−1; 10 kg∙ha−1; and 0 kg∙ha−1). We adopted gas chromatography-mass spectrometry to assess the response of primary metabolites of different plant tissues (flowers, main shoots, lateral shoots and roots) to phosphorus fertilization. At the same time, high-performance liquid chromatography was used to quantify saikosaponin A and saikosaponin D, the main active ingredients of Bupleurum. Our research showed that low phosphorus level application has a positive impact on the yield and quality of Bupleurum, especially the above-ground parts increasing the fresh weight of flowers and lateral shoots and the length of main shoots, and moreover, increasing the saikosaponins content in all above-ground parts while decreasing the content in roots which show no significance increase in fresh weight and length. However, high phosphorus level showed a negative impact as it decreases the saikosaponins content significantly in flowers and roots. Furthermore, phosphorus application changed the proportion of saikosaponins, promoting the content of saikosaponin A and inhibiting the content of saikosaponin D in most organs of Bupleurum. Therefore, we can say that high phosphorus application is not preferable to the yield and quality of Bupleurum. To identify the metabolic pathways and special key metabolites, a total of 73 metabolites were discovered, and four differential metabolites—ether, glycerol, chlorogenic and L-rhamnose—were considered to be the key metabolites of Bupleurum's response to phosphorus fertilization. Furthermore, Bupleurum's response to phosphorus fertilization was mainly related to metabolic pathways, such as starch and sucrose metabolism and galactose metabolism. Under the phosphorus level, the content of sugars, organic acids and their derivatives, polyols and their derivatives and alkyl were upregulated in flowers. Furthermore, the contents of compounds in the main shoot and lateral shoots showed the same upward trend, except glycosides and polyols and their derivatives. [ABSTRACT FROM AUTHOR]

Inorganic phosphate (Pi) is stored in the vacuole, allowing plants to adapt to variable Pi availability in the soil. The transporters that mediate Pi sequestration into vacuole remain unknown, however. Here we report the functional characterization of Vacuolar Phosphate Transporter 1 (VPT1), an SPX domain protein that transports Pi into the vacuole in Arabidopsis. The vpt1 mutant plants were stunted and consistently retained less Pi than wild type plants, especially when grown in medium containing high levels of Pi. In seedlings, VPT1 was expressed primarily in younger tissues under normal conditions, but was strongly induced by high-Pi conditions in older tissues, suggesting that VPT1 functions in Pi storage in young tissues and in detoxification of high Pi in older tissues. As a result, disruption of VPT1 rendered plants hypersensitive to both low-Pi and high-Pi conditions, reducing the adaptability of plants to changing Pi availability. Patch-clamp analysis of isolated vacuoles showed that the Pi influx current was severely reduced in vpt1 compared with wild type plants. When ectopically expressed in Nicotiana benthamiana mesophyll cells, VPT1 mediates vacuolar influx of anions, including Pi, SO4(2-), NO3(-), Cl(-), and malate with Pi as that preferred anion. The VPT1-mediated Pi current amplitude was dependent on cytosolic phosphate concentration. Single-channel analysis showed that the open probability of VPT1 was increased with the increase in transtonoplast potential. We conclude that VPT1 is a transporter responsible for vacuolar Pi storage and is essential for Pi adaptation in Arabidopsis.

Available phosphorus (AP) requirement for tambaqui (Colossoma macropomum) was evaluated using different response parameters, and CT scanning was used to determine the adequacy of dietary P along with bone mineralization data. A total of 192 tambaqui juveniles (17 ± 0.85 g) were stocked into 24 70 L‐tanks using randomized block design (different floors) with six treatments (1.3, 2.4, 4.8, 6.3, 7.8 and 8.8 g kg−1 AP) and four replicates. Fish were fed ad libitum with six semi‐purified diets containing graded levels of AP for 90 days. The dietary AP requirement was estimated using non‐linear regression models. No mortality or apparent signs of P deficiency were observed. Increasing dietary AP levels improved all performance variables. Dietary P levels significantly affected bone density. The estimated P requirement for tambaqui was 6.3, 3.68, 5.0 and 6.91 g kg−1 diet for improved weight gain, bone density, vertebrae mineralization and carcass mineral deposition, respectively. CT scanning allowed the visualization of bone structures affected by P deficiency and could predict the P requirement based on vertebrae mineralization. Additionally, blood chemistry parameters were significantly affected by the dietary P level, except for serum calcium. Thus, the use of 6.3 g kg−1 AP in tambaqui diets can maintain normal growth and bone mineralization of juveniles from 17–150 g. [ABSTRACT FROM AUTHOR]

Alfalfa planting is threatened by limited arable land, salinization, water shortage, and soil nutrient deprivation. To deal with this challenge, we previously introduced the Arabidopsis type I H+-pyrophosphatase gene AVP1 into alfalfa and found that transgenic lines exhibited enhanced tolerance to short-term salinity or drought. In this study, the growth performances of two transgenic lines were further investigated under long-term salinity or drought conditions, as well as under phosphate deficiency (low-Pi). Compared with wild-type (WT) plants, the transgenic alfalfa showed better growth performance with taller plants and more biomass accumulation after being treated with either long-term salinity, long-term drought, or low-Pi. Most importantly, the overexpression of AVP1 significantly increased the root dry weight and the root/shoot ratio of transgenic alfalfa. A more robust root system facilitates the transgenic alfalfa to absorb nutrients, and in turn promotes the growth of the plants. Whether being treated with low-Pi or not, transgenic plants showed higher total phosphorus concentrations by 16.5-35.5% than WT plants. This study laid a foundation for breeding alfalfa cultivars adapted to saline, arid and nutrient-deprived marginal land.

ABSTRACT Phosphorus (P) is one of the most difficult nutrients for plants to acquire because of its low content in the soil solution. Cassava (Manihot esculenta Crantz) has a thick and sparse absorbent root system; therefore, it is dependent on its association with arbuscular mycorrhizal fungi (AMF) for P acquisition from the soil. Thus, inoculation of cassava with AMF can improve the development of this root crop. This study evaluated the effects of soil disinfection (disinfected vs. natural) and the spore rates of Rhizophagus clarus inoculation (0, 50, 100 and 200 spores per plant) in greenhouse conditions on the initial growth, yield, P acquisition, and P use efficiency of cassava, as well as to evaluate the contribution of the native AMF to P acquisition from the soil. For cassava production in P-deficient soil, inoculation with Rhizophagus clarus significantly increased cassava growth, P uptake, and storage root yield only when the soil was disinfected. When the soil is not disinfected, native AMF contributes up to 86 % of the P taken up by cassava. However, high spore rates of Rhizophagus clarus in natural soil cause detrimental consequences for native AMF by reducing the colonization of the absorbent roots. Therefore, for cassava grown in natural soil under greenhouse conditions, a rate of 50 spores per plant of Rhizophagus clarus is sufficient to promote a 14.5 % increase in the yield of fresh storage roots. A management strategy that favors the native AMF multiplication in the soil is a potential strategy to improve P uptake and yield of cassava in P-deficient soils.

Reducing phosphate fertilizer inputs while increasing food nutritional quality has been posited as a major challenge to decrease human undernourishment and ensure food security. In this context, quinoa has emerged as a promising crop due to its ability to tolerate different stress conditions and grow in marginal soils with low nutrient content, in addition to the exceptional nutritional quality of its grains. However, there is scarce information about the phosphorus acquisition capacity of quinoa roots. This work aimed to provide new insights into P acquisition and functional root traits, such as root biomass, rhizosphere pH, carboxylate exudation, and acid phosphatase activity of thirty quinoa genotypes grown under P limiting conditions (7 mg P kg−1). Significant genotypic variation was observed among genotypes, with average P accumulation ranging from 1.2 to 11.8 mg. The shoot biomass production varied more than 14 times among genotypes and was correlated with the P accumulation on shoots (r = 0.91). Despite showing high variability in root traits, only root biomass production highly correlated with P acquisition (r = 0.77), suggesting that root growth/morphology rather than the measured biochemical activity possesses a critical role in the P nutrition of quinoa.

Summary: Efficient phosphate (Pi) uptake and utilisation are essential for promoting crop yield. However, the underlying molecular mechanism is still poorly understood in complex crop species such as hexaploid wheat. Here we report that TaPHT1;9‐4B and its transcriptional regulator TaMYB4‐7D function in Pi acquisition, translocation and plant growth in bread wheat.TaPHT1;9‐4B, a high‐affinity Pi transporter highly upregulated in roots by Pi deficiency, was identified using quantitative proteomics. Disruption of TaPHT1;9‐4B function by BSMV‐VIGS or CRISPR editing impaired wheat tolerance to Pi deprivation, whereas transgenic expression of TaPHT1;9‐4B in rice improved Pi uptake and plant growth. Using yeast‐one‐hybrid assay, we isolated TaMYB4‐7D, a R2R3 MYB transcription factor that could activate TaPHT1;9‐4B expression by binding to its promoter. Silencing TaMYB4‐7D decreased TaPHT1;9‐4B expression, Pi uptake and plant growth.Four promoter haplotypes were identified for TaPHT1;9‐4B, with Hap3 showing significant positive associations with TaPHT1;9‐4B transcript level, growth performance and phosphorus (P) content in wheat plants. A functional marker was therefore developed for tagging Hap3.Collectively, our data shed new light on the molecular mechanism controlling Pi acquisition and utilisation in bread wheat. TaPHT1;9‐4B and TaMYB4‐7D may aid further research towards the development of P efficient crop cultivars. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of arbuscular mycorrhizal fungus (AMF) Rhizophagus intraradices on plant growth and phosphorus (P) uptake of soybean (Glycine max L.) in soils contaminated with different concentrations of heavy metals [copper (100 and 300 mg kg−1), lead (100 and 300 mg kg−1) and zinc (300 and 600 mg kg−1)] and combination (Cu100 + Pb100 + Zn300) in a pot experiment. The bioaccumulation characteristics of the heavy metals in the plant tissues in terms of bioabsorption coefficient (BAC), bioconcentration factor (BCF) and translocation factor (TF) were also evaluated. The results showed R. intraradices inoculation significantly (p <.01) enhanced soybean growth, P uptake and grain yield in all polluted soils compared to non-inoculated treatment. In addition, R. intraradices retained most of the heavy metals in the roots, with lesser translocation to the shoots and seeds. Exposure to 600 mg Zn kg−1 soil remarkably reduced the plant growth, P content and seed yield of the soybean. Copper uptake in the shoot was significantly increased in multi-metal contaminated soil with reduced lead and zinc compared to single polluted soils. This work suggests that Rhizophagus intraradices inoculation may be a potential and effective of AMF isolate for enhancing plant growth, P nutrition and stress tolerance in heavy metal-contaminated soil [ABSTRACT FROM AUTHOR]

The module GA-GID1-DELLA (Gibberellin-Gibberellin Receptor-DELLA proteins) provides a point for the integration of signals potentially relevant in determining nutrient utilisation and acquisition efficiencies. In this study, we explored the role of components of this module during the acclimation of barley plants (Hordeum vulgare L.) to different phosphorus (P) supplies by using two related genotypes, harbouring either theWTor the Sln1d alleles of the DELLA-coding gene Sln1. Dwarf Sln1d plants exhibited reduced shoot P utilisation efficiency (PUtE) and better performance at low levels of P supply. The superior PUtE displayed byWTplants disappeared when corrected by internal P concentration, indicating that multiple analyses are necessary to fully understand the meaning of PUtE estimates. Over a wide range of external supplies of P, Sln1d plants displayed enhanced P concentration, which was associated with low relative growth rate, high biomass partitioning to roots and high P-uptake-rate, thus suggesting that the effect of the Sln1d allele on P dynamics is not simply a consequence of slow growth habit. An enhanced P concentration was also found in a mutant with defective GAssynthesis. Our results suggest that components of theGA-GID1-DELLAsmodule contribute to set the acclimation response of barley plants to low P supply through both P-dynamics dependent and P-dynamics independent mechanisms. [ABSTRACT FROM AUTHOR]

European beech is one of the most important deciduous tree species in natural forest ecosystems in Central Europe. Its dominance is now being questioned by the emerging drought damages due to the increased incidence of severe summer droughts. In Switzerland, Fagus sylvatica have been observed in the Intercantonal Forest Observation Program since 1984. The dataset presented here includes 179176 annual observations of beech trees on 102 plots during 37 years. The plots cover gradients in drought, nitrogen deposition, ozone, age, altitude, and soil chemistry. In dry regions of Switzerland, the dry and hot summer of 2018 caused a serious branch dieback, increased mortality in Fagus sylvatica and increased yellowing of leaves. Beech trees recovered less after 2018 than after the dry summer 2003 which had been similar in drought intensity except that the drought in 2018 started earlier in spring. Our data analyses suggest the importance of drought in subsequent years for crown transparency and mortality in beech. The drought in 2018 followed previous dry years of 2015 and 2017 which pre-weakened the trees. Our long-term data indicate that the drought from up to three previous years were significant predictors for both tree mortality and for the proportion of trees with serious (>60%) crown transparency. The delay in mortality after the weakening event suggests also the importance of weakness parasites. The staining of active vessels with safranine revealed that the cavitation caused by the low tree water potentials in 2018 persisted at least partially in 2019. Thus, the ability of the branches to conduct water was reduced and the branches dried out. Furthermore, photooxidation in light-exposed leaves has increased strongly since 2011. This phenomenon was related to low concentrations of foliar phosphorus (P) and hot temperatures before leaf harvest. The observed drought effects can be categorized as (i) hydraulic failure (branch dieback), (ii) energy starvation as a consequence of closed stomata and P deficiency (photooxidation) and (iii) infestation with weakness parasites (beech bark disease and root rots).

Arbuscular mycorrhizal fungi (AMF) symbiosis can enhance plant growth in unfavorable conditions. However, functional variations among different AMF species for their ability to enhance phosphorus (P) uptake and soybean tolerance in lead (Pb) contaminated soil have rarely been examined. The present study therefore aimed to compare the growth, P uptake and Pb tolerance of soybean plants colonized by different AMF and to test the relationship between P uptake efficiency and Pb uptake in Pb contaminated soil. Soybean inoculated with three different AMF, Funneliformis mosseae, Claroideoglomus etunicatum, and Rhizophagus intraradices and control was grown under three Pb addition levels (0, 100 and 300 mg kg−1) in a pot experiment. The results showed that AMF inoculation significantly promoted the plant growth, P uptake and Pb accumulation in the roots, with less translocation of Pb from roots to the shoots compared to non-inoculated plants. Soybean plants inoculated with R. intraradices were more tolerant to Pb toxicity compared with other two AMF species in terms of higher root colonization, biomass, P uptake and seed yield. Significant linear correlations were observed between biomass, P uptake and Pb uptake of the plant. The findings in this study are essential in using AMF to promote soybean growth and P uptake in heavy metal-contaminated soils. Moreover, symbiotic P uptake and retention of Pb in roots of plants could serve as important criteria for screening of efficient AMF species or isolates for plant growth, P nutrition and metal tolerance in heavy metal contaminated soils. [ABSTRACT FROM AUTHOR]

Phosphorus is an essential macronutrient for plant growth and development. Root system architecture (RSA) affects a plant's ability to obtain phosphate, the major form of phosphorus that plants uptake. In this review, I first consider the relationship between RSA and plant phosphorus‐acquisition efficiency, describe how external phosphorus conditions both induce and impose changes in the RSA of major crops and of the model plant Arabidopsis, and discuss whether shoot phosphorus status affects RSA and whether there is a universal root developmental response across all plant species. I then summarize the current understanding of the molecular mechanisms governing root developmental responses to phosphorus deficiency. I also explore the possible reasons for the inconsistent results reported by different research groups and comment on the relevance of some studies performed under laboratory conditions to what occurs in natural environments. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency affects plant yield and quality, yet at the same time, excessive phosphorus application does not necessarily promote the growth of plants. How to maintain a balance between biomass accumulation and phosphorus application is a problem. Therefore, the purpose of this research was to explore the relationship between yield and quality of Bupleurum and phosphorus fertilization, based on three phosphorus fertilization levels (20 kg∙ha−1; 10 kg∙ha−1; and 0 kg∙ha−1). We adopted gas chromatography-mass spectrometry to assess the response of primary metabolites of different plant tissues (flowers, main shoots, lateral shoots and roots) to phosphorus fertilization. At the same time, high-performance liquid chromatography was used to quantify saikosaponin A and saikosaponin D, the main active ingredients of Bupleurum. Our research showed that low phosphorus level application has a positive impact on the yield and quality of Bupleurum, especially the above-ground parts increasing the fresh weight of flowers and lateral shoots and the length of main shoots, and moreover, increasing the saikosaponins content in all above-ground parts while decreasing the content in roots which show no significance increase in fresh weight and length. However, high phosphorus level showed a negative impact as it decreases the saikosaponins content significantly in flowers and roots. Furthermore, phosphorus application changed the proportion of saikosaponins, promoting the content of saikosaponin A and inhibiting the content of saikosaponin D in most organs of Bupleurum. Therefore, we can say that high phosphorus application is not preferable to the yield and quality of Bupleurum. To identify the metabolic pathways and special key metabolites, a total of 73 metabolites were discovered, and four differential metabolites—ether, glycerol, chlorogenic and L-rhamnose—were considered to be the key metabolites of Bupleurum’s response to phosphorus fertilization. Furthermore, Bupleurum’s response to phosphorus fertilization was mainly related to metabolic pathways, such as starch and sucrose metabolism and galactose metabolism. Under the phosphorus level, the content of sugars, organic acids and their derivatives, polyols and their derivatives and alkyl were upregulated in flowers. Furthermore, the contents of compounds in the main shoot and lateral shoots showed the same upward trend, except glycosides and polyols and their derivatives.

Studies on the effect of high atmospheric N deposition report inconsistent results on forest productivity and N cycling which might be related to P availability in soil and subsequently affect tree P nutrition. We wanted to test the effects of (i) site i.e., a P-poor versus a P-rich site and of (ii) fertilization (N,P,N+P) on inorganic P (Pi) and organic P (Po) concentrations as well as on biologically cycled phosphate (inferred from the O isotope signature after adding an 18O-enriched label) in xylem sap. We measured Pi and Po concentrations and the O isotope signature in phosphate (δ18OPi) in xylem sap of beech (Fagus sylvatica L.) trees two and 14 days after addition of 18O-enriched water to the organic layer in a full factorial fertilization experiment (control, +N, +P, +NP) at two sites differing in P availability. Higher P concentrations in xylem sap at the P-rich than at the P-poor site originated from accelerated biological P cycling indicated by incorporation of 18O from the isotope label into phosphate in xylem sap shortly after labeling. At this site, δ18OW values of xylem sap after label application remained close to background δ18OW values of soil solution. We speculate that in contrast to P uptake, trees took up water from deeper (non-18O-labeled) soil layers. At the P-poor site, the 18O label was recovered both in xylem sap water and phosphate in xylem sap, the latter only after 14 days. These results imply that trees relied on the organic layer for P acquisition and water uptake. However, biological processes associated with an incorporation of 18O from the label were slower at the P-poor than at the P-rich site. P addition (P,NP) increased Pi concentrations in xylem sap at the P-rich site. Based on δ18OPi values in xylem sap, the additional P originated both from the fertilizer and from accelerated biological P cycling in soil. We conclude that P-poor sites likely suffer more from climate change in case of an increased frequency of droughts because as opposed to P-rich sites both water and nutrient uptake will be affected.

In forests, where the supply of bioavailable phosphorus (P) from easily weatherable primary minerals is small, plants are thought to recycle P efficiently by uptake of P released from decomposing forest floor material. Yet a share of the P is leached into the subsoil, where it is strongly adsorbed onto the reactive surfaces of pedogenic Fe and Al oxides. This raises the question of whether P leached into subsoil is also recycled. To investigate the mobilization of P bound to hydrous Fe oxides, we conducted a mesocosm experiment in a greenhouse. Beech saplings were grown for 14 months in subsoil material (Bw horizon from the P-poor Lüss beech forest) with added goethite-P adsorption complexes, in either inorganic (orthophosphate) or organic (phytate) form. Four types of control mesocosms were run: soil only and soil mixed with either dissolved orthophosphate or dissolved phytate or goethite. At the end of the experiment, neither total P mass in trees nor P contents in leaves differed between the treatments. According to leaf nutrient contents, plant growth was strongly limited by P in all treatments. Yet total P mass in trees did not increase over the course of the experiment. Thus, despite its P demand, beech was not able to acquire P from goethite surfaces within two vegetation periods. Also P added in dissolved form to the soil before transplanting as well as native soil P were not available. This suggests that, once inorganic and organic P is bound to pedogenic metal oxides in mineral soil, it is not or hardly recycled, which can be an explanation for field data demonstrating quantitatively significant stocks of P in the subsoil of P-deficient forests.

A completed hedgerow of cv. Arbequina and a youth vase trained orchard of cv. Picual were fertilized with foliar applications of Phosphorus (P) or Potassium (K) throughout four seasons. The orchards were located near Valdepeñas in the dry area of La Mancha (Spain). Vegetative growth, yield and oil quality were evaluated. Foliar treatments did not increase P or K leaf concentration. Most of the evaluated parameters were not significantly affected by treatments. It was observed that the P treatment increased olive growth and oil yield in both orchards and in certain seasons due to an increment in fruit number. P and K application significantly increased ‘Arbequina’ olive and oil yield in 2008 when spring was wetter than the other years. Oil quality was not modified by fertilizer treatments in the ‘Arbequina’orchard. However, oxidative stability was negatively affected by P and K treatments in ‘Picual’. Oil extraction could be negatively affected by treatments because of the increase in the water content in the fruit obtained from both orchards.

Beech (Fagus sylvatica) and silver fir (Abies alba) are often cultivated in mixed stands and, hence, compete for water and nutrients. Besides nitrogen (N), also phosphorus (P) is an important nutrient for growth and development. Beech trees in Central Europe grow on both P-poor and P-rich soils, thereby showing similar growth and low variation in foliar P. The central aim of the present study was to test the hypothesis that variations in foliar P contents of beech are driven by seasonal changes rather than by the competition with silver fir. It was further hypothesized that P contents in silver fir needles depend on needle age and forest site. To test these hypotheses, P contents and P fractions, i.e. organic-bound P (Porg) and inorganic phosphate P (Pi), were measured in the foliage of beech trees from pure beech and mixed beech/silver fir plots as well as in needles of silver fir of the mixed plots. The forest sites investigated are located in Central Europe in the Black Forest, Germany, and in Croatia near the south-eastern distribution limit of beech and are all poor in plant-available soil P. The analyses showed that the main driver of P contents and P fractions in beech leaves at all forest sites is the season and that competition with silver fir had no effect. Hence, the present results demonstrate the high plasticity of beech trees to adapt to both poor plant-available soil P and competition with silver fir. Total P contents of silver fir needles were higher at the Croatian site compared to the Black Forest sites and originated from higher foliar Pi contents. One third of the P present in current-year needles in late summer was remobilized and exported until the needles reached the age of 1 year. The difference in P contents between current-year and 1-year-old needles can be seen as the amount of P resorbed from 1-year-old needles in summer during the generation of new needles to support the P demand of current-year needles for growth and development. [ABSTRACT FROM AUTHOR]

A completed hedgerow of cv. Arbequina and a youth vase trained orchard of cv. Picual were fertilized with foliar applications of Phosphorus (P) or Potassium (K) throughout four seasons. The orchards were located near Valdepeñas in the dry area of La Mancha (Spain). Vegetative growth, yield and oil quality were evaluated. Foliar treatments did not increase P or K leaf concentration. Most of the evaluated parameters were not significantly affected by treatments. It was observed that the P treatment increased olive growth and oil yield in both orchards and in certain seasons due to an increment in fruit number. P and K application significantly increased 'Arbequina' olive and oil yield in 2008 when spring was wetter than the other years. Oil quality was not modified by fertilizer treatments in the 'Arbequina'orchard. However, oxidative stability was negatively affected by P and K treatments in 'Picual'. Oil extraction could be negatively affected by treatments because of the increase in the water content in the fruit obtained from both orchards. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizas (AM) can improve phosphorus (P) nutrition and could serve as an environmentally friendly approach for sustainable crop production under P-limiting conditions. The objectives of this study were to assess the effect of AM on different physiological traits and to quantify the responsiveness of different basil (Ocimum basilicum L.) cultivars to AM under low P availability. The basil cultivars ‘Genovese’, ‘Sweet Basil’, ‘Dark Opal’, and ‘Erevanskii’ were inoculated (AMI) using Rhizophagus irregularis. Photochemical efficiency and gas exchange were measured on AMI and non-inoculated (AMC) plants and, at harvest, the shoot biomass, shoot P concentration, root morphological traits, frequency of mycorrhizas in the roots (F%), and extent of root colonization (M%) were determined. Significant differences in F% and M% were found among the examined cultivars, with the highest found in ‘Dark Opal‘ and the lowest in ‘Erevanskii‘. AMI reduced the shoot biomass and increased the shoot P concentration as well as other examined root traits in ‘Genovese’ and ‘Erevanskii’, whereas it did not affect those traits in ‘Dark Opal’ and ‘Sweet Basil’, indicating differences in responsiveness to AM. AMI positively affected the gas-exchange parameters in all examined cultivars, probably due to the increased sink capacity of a bigger root system and/or AM structures within the roots. [ABSTRACT FROM AUTHOR]

Strawberry nursery plants require chilling and also a high acquisition of phosphorus nutrition for helping capture and transfer energy for its rapid top growth. Soil phosphorus availability can be reduced in presence of high soil Fe, Ca and Mg concentrations in the adsorption process, which can vary with soil water content (SWC) and pH levels. A study was conducted in two commercial nursery plant production fields in the temperate Atlantic coastal areas in 2008. The objectives were to examine soil P availability, strawberry nursery plant propagation and P acquisition in relation to different soil pH, SWC and Ca, Mg and Fe concentrations. The cultivar ‘Strawberry Festival’ was used in the study and measurements were systematically taken along transects. The strawberry nursery plant propagation and productivity expressed using runners and daughter plants were significantly related to soil P availability, soil water and pH levels (0.50 < R2 < 0.61, P < 0.05). Soil soluble P concentrations were associated with soil water, pH and Ca, Mg and Fe concentrations. Strawberry produced 25 runners and 17 daughter plants in the soil with the optimal pH (6.5) and higher SWC and P availability, a 60% higher nursery productivity than that in the acidic soil (pH 5.7). Soil P concentrations were decreased while Ca, Mg and Fe cations were high in the acidic conditions. It was suggested that soil P could be fixed rapidly and thus result in low strawberry nursery productivity.

Alfalfa planting is threatened by limited arable land, salinization, water shortage, and soil nutrient deprivation. To deal with this challenge, we previously introduced the Arabidopsis type I H+-pyrophosphatase gene AVP1 into alfalfa and found that transgenic lines exhibited enhanced tolerance to short-term salinity or drought. In this study, the growth performances of two transgenic lines were further investigated under long-term salinity or drought conditions, as well as under phosphate deficiency (low-Pi). Compared with wild-type (WT) plants, the transgenic alfalfa showed better growth performance with taller plants and more biomass accumulation after being treated with either long-term salinity, long-term drought, or low-Pi. Most importantly, the overexpression of AVP1 significantly increased the root dry weight and the root/shoot ratio of transgenic alfalfa. A more robust root system facilitates the transgenic alfalfa to absorb nutrients, and in turn promotes the growth of the plants. Whether being treated with low-Pi or not, transgenic plants showed higher total phosphorus concentrations by 16.5-35.5% than WT plants. This study laid a foundation for breeding alfalfa cultivars adapted to saline, arid and nutrient-deprived marginal land. [ABSTRACT FROM AUTHOR]

Although used as an additional nutritional source of phosphorus in agriculture, little is known about the effects of phosphites on plants. In order to evaluate the influence of phosphite and phosphate on the accumulation and translocation of phosphorus and cationic nutrients, in common bean, three experiments were conducted. In the first experiment, five concentrations (0.5 mg L-1, 10 mg L-1, 20 mg L-1, 30 mg L-1 and 60 mg L-1) were studied in a nutrient solution combined with two forms of phosphorus [phosphate (Pi) and phosphite (Phi)]. In the second one, five Phi/Pi ratios were tested (0/100, 25/75, 50/50, 75/25 and 100/0). In the third experiment, two phosphate levels (1.5 mg L-1 = limiting and 20 mg L-1 = adequate phosphorus) and three treatments related to foliar fertilization (KH2PO3, KH2PO4 and KCl solutions) were combined in the nutrient solution. Phosphite via roots caused a decrease in the accumulation of phosphorus and cationic nutrients, under phosphate deficiency. P-Phi decreased the Zn/P ratio more than P-Pi, increased the translocation of P and decreased the translocation of Fe. The foliar supply of P-Phi did not affect the phosphorus nutrition of bean plants or the translocation of nutrients, but decreased the accumulation of K, Ca, Mg, Fe and Mn. Foliar P-Pi, at an adequate P supply in the nutrient solution, increased the accumulation of this nutrient.

The natural grasslands in South America have soils with low phosphorus (P) availability (1.0 to 7.5 mg kg−1), possibly altering the absorption and accumulation of P in grasses. We evaluated the chemical fractionation of P in the leaves of the most important grasses present in these grasslands to better understand the mechanisms involved in the storage of P. The grasses studied were Axonopus affinis and Paspalum notatum (fast tissue cycling and high nutrient demand) and Andropogon lateralis and Aristida laevis (slow tissue cycling and low nutrient demand). They were grown in pots filled with an Ultisol with two levels of P: control, and addition of 50 mg P kg–1. The main P fractions were the inorganic soluble (44%) and P in RNA (26%). Addition of P increased the total P concentration, following the order A. affinis (140%) > P. notatum (116%) > A. lateralis (81%) > A. laevis (21%). In conclusion, the species A. affinis and P. notatum responded to P fertilization with high variation and accumulating P in less-structural chemical forms, such as inorganic P. The species A. lateralis and A. laevis showed low variation in the concentration of P forms, with higher P concentrations in structural forms. [ABSTRACT FROM AUTHOR]

Highlights • Arbuscular mycorrhiza is a sustainable strategy to increase plant Pi uptake. • Mycorrhizal plants have Pi uptake pathways. • The mycorrhizal Pi uptake pathway can dominate plant Pi uptake. • Symbiotic Pi transport is mediated by mycorrhiza-specific Pi transporters. • Pi acts as a signal in the symbiosis. Abstract Phosphorus (P) is a poorly available macronutrient essential for plant growth and development and consequently for successful crop yield and ecosystem productivity. To cope with P limitations plants have evolved strategies for enhancing P uptake and/or improving P efficiency use. The universal 450-million-yr-old arbuscular mycorrhizal (AM) (fungus-root) symbioses are one of the most successful and widespread strategies to maximize access of plants to available P. AM fungi biotrophically colonize the root cortex of most plant species and develop an extraradical mycelium which overgrows the nutrient depletion zone of the soil surrounding plant roots. This hyphal network is specialized in the acquisition of low mobility nutrients from soil, particularly P. During the last years, molecular biology techniques coupled to novel physiological approaches have provided fascinating contributions to our understanding of the mechanisms of symbiotic P transport. Mycorrhiza-specific plant phosphate transporters, which are required not only for symbiotic P transfer but also for maintenance of the symbiosis, have been identified. The present review provides an overview of the contribution of AM fungi to plant P acquisition and an update of recent findings on the physiological, molecular and regulatory mechanisms of P transport in the AM symbiosis. [ABSTRACT FROM AUTHOR]

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]

Aims: The accumulation of organic layers in forests is linked to decreasing nutrient availability. Organic layers might represent a source of phosphorus (P) nutrition of trees in forests. Our aims were i) to test if the fate of P in a tree sapling-soil system differs between nutrient-poor and nutrient-rich sites, and ii) to assess the influence of organic layers on the fate of P in a tree sapling-soil system at either site.Methods: We conducted a 33P labeling experiment of mesocosms of beech (Fagus sylvatica) saplings.Results: Recovery of 33P in the organic layer was greater under nutrient-poor than under nutrient-rich conditions likely caused by the abundance of microorganisms and roots. Under nutrient-poor conditions, we found that the mobilization of P followed by efficient uptake promoted tree sapling growth if the organic layer was present. The presence of organic layers did not significantly influence P uptake by beech saplings under nutrient-rich conditions suggesting mechanisms of P mobilization in addition to organic matter mineralization.Conclusions: Our results highlight the importance of organic layers for P nutrition of young beech trees growing on nutrient-poor soils in temperate forest ecosystems. The role of organic layers should be considered for sustainable forest management. [ABSTRACT FROM AUTHOR]

Precise diagnosis and prognosis of phosphorus (P) nutrition are essentials to improve P use efficiency and sustainability in potato cropping systems. Here, variable potato crop responses of 13 field experiments (2011–2022) were assessed to determine critical soil P-resin (SP resin) and potato leaf P (LP) concentrations to achieve maximum tuber yield in tropical Oxisols. The study comprised four experiments with the factorial design of potato cultivars in response to P fertilization rates and nine experiments with P fertilization rates as fixed effects. Relationships between initial SP resin test, LP measured at the third or fourth expanded leaf stage (i.e., 29–37 days after emergence, DAE), and relative total fresh tuber yield (RY) (yield of control/yield at highest P rate) were analyzed using linear-plateau, Mitscherlich, and quadratic-plateau regression models. A wide range of total fresh tuber yield (3.2–59 Mg ha-1) and LP (1.3–5.7 g P kg-1) were observed across experiments. The LP values in control plots was positively related with initial SP resin , reaching a maximum LP of 3.8 g P kg-1 at an initial SP resin of 80 mg P dm-3 (averaged across models). The relationship between RY and initial SP resin was significant in the three regression models (p < 0.05; R 2 = 0.71–0.74). Maximum tuber yield was reached with the SP resin value of 93 mg P dm-3 (averaged across models). Across experiments and P fertilization rates, relationships between RY and LP were significantly described in the three regression models (p < 0.05; R 2 = 0.55–0.67). The critical LP of 4.5 g P kg-1, obtained from the average across models, is proposed as the optimum indicator of potato P nutritional status to achieve maximum tuber yields in tropical Oxisols. These are the first critical P thresholds on a soil and environmental-specific conditions base available for tropical conditions in Brazil, timely informative in terms of optimization of P management to maximize tuber yield and P use efficiency, and minimize the risk of environmental P contamination. • Data from 13 experiments were used to assess potato crop response to P fertilization. • A wide range of tuber yield (3.2–59 Mg ha-1) and leaf P concentration (1.3–5.7 g P kg-1) were observed across experiments. • No further positive yield response was observed when initial soil P-resin was above the critical threshold of 93 mg P dm-3. • Leaf concentration of 4.5 g P kg-1 is proposed as indicator of optimum P nutritional status for potatoes. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is one of the most important macronutrients limiting plant growth and development, particularly in forest ecosystems such as temperate beech (Fagus sylvatica) forests in Central Europe. Efficient tree internal P cycling during annual growth is an important strategy of beech trees to adapt to low soil-P. Organic P (Porg) is thought to play a decisive role in P cycling, but the significance of individual compounds and processes has not been elucidated. To identify processes and metabolites involved in P cycling of beech trees, polar-metabolome and lipidome profiling was performed during annual growth with twig tissues from a sufficient (Conventwald, Con) and a low-soil-P (Tuttlingen, Tut) forest. Autumnal phospholipid degradation in leaves and P export from senescent leaves, accumulation of phospholipids and glucosamine-6-phosphate (GlcN6P) in the bark, storage of N-acetyl-D-glucosamine-6-phosphate (GlcNAc6P) in the wood, and establishing of a phospholipid “start-up capital” in buds constitute main processes involved in P cycling that were enhanced in beech trees on low-P soil of the Tut forest. In spring, mobilization of P from storage pools in the bark contributed to an effective P cycling. Due to the higher phospholipid “start-up capital” in buds of Tut beeches, the P metabolite profile in developing leaves in spring was similar in beech trees of both forests. During summer, leaves of Tut beeches meet their phosphate (Pi) needs by replacing phospholipids by galacto- and sulfolipids. Thus, several processes contribute to adequate Pi supply on P impoverished soil thereby mediating similar growth of beech at low and sufficient soil-P availability.

Phosphorus (P) is an important nutrient, whose plant-available form phosphate is often low in natural forest ecosystems. Mycorrhizal fungi mine the soil for P and supply their host with this resource. It is unknown how ectomycorrhizal communities respond to changes in P availability. Here, we used young beech (Fagus sylvatica L.) trees in natural forest soil from a P-rich and P-poor site to investigate the impact of P amendment on soil microbes, mycorrhizas, beech P nutrition, and photosynthesis. We hypothesized that addition of P to forest soil increased P availability, thereby, leading to enhanced microbial biomass and mycorrhizal diversity in P-poor but not in P-rich soil. We expected that P amendment resulted in increased plant P uptake and enhanced photosynthesis in both soil types. Young beech trees with intact soil cores from a P-rich and a P-poor forest were kept in a common garden experiment and supplied once in fall with triple superphosphate. In the following summer, labile P in the organic layer, but not in the mineral top soil, was significantly increased in response to fertilizer treatment. P-rich soil contained higher microbial biomass than P-poor soil. P treatment had no effect on microbial biomass but influenced the mycorrhizal communities in P-poor soil and shifted their composition toward higher similarities to those in P-rich soil. Plant uptake efficiency was negatively correlated with the diversity of mycorrhizal communities and highest for trees in P-poor soil and lowest for fertilized trees. In both soil types, radioactive P tracing (H333PO4) revealed preferential aboveground allocation of new P in fertilized trees, resulting in increased bound P in xylem tissue and enhanced soluble P in bark, indicating increased storage and transport. Fertilized beeches from P-poor soil showed a strong increase in leaf P concentrations from deficient to luxurious conditions along with increased photosynthesis. Based on the divergent behavior of beech in P-poor and P-rich forest soil, we conclude that acclimation of beech to low P stocks involves dedicated mycorrhizal community structures, low P reserves in storage tissues and photosynthetic inhibition, while storage and aboveground allocation of additional P occurs regardless of the P nutritional status.