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Understanding the changes in the root system architecture of bread wheat under phosphorus (P)-limited conditions is critical for identifying specific traits contributing to improved P uptake. Phenotypic variability in root, biomass, and P index-related traits among 204 diverse wheat genotypes at the seedling stage was examined under low and optimum P treatments. Strong genotypic and phenotypic associations between P utilization efficiency (PUtE) and total root volume, dry weight of root and shoot, total P uptake, and total plant biomass were observed under optimum P. Under low P, strong positive correlations between PUtE and total root length, total root volume, total surface area, and total biomass were observed, while it was negatively correlated with average diameter. These traits exhibited medium to high heritability. Under low P, average root diameter, primary root length, root mass ratio, total root tips, and surface area showed high Shannon–Weaver diversity index (H') values (>0.79). The agglomerative hierarchical clustering analysis grouped the genotypes into four distinct clusters. The best performing genotypes in Clusters I and II indicated their strong relationship with P use efficiency due to higher percent increases in total root length, total surface area, total root volume, total root tips, total biomass, P efficiency ratio, specific root length, and PUtE under low P as compared to optimum P conditions. The present study identified specific root system architectural traits and P use-efficient genotypes (SHANGHAI, Pavon F76, BWL 5233, SONALIKA, KHARCHIA LOCAL, WH 102, BWL 4425, HD 2888.2, CBW 12, MN75136/PGO, KRL 19, and WH 1022) associated with efficient P uptake and utilization. These identified genotypes and traits may be useful in wheat breeding programs to develop P-efficient varieties with better adaptations for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Yield potential of maize having distinct genetic diversity in Eastern Himalayan Region (EHR) hill ecologies is often limited by Al toxicity caused due to soil acidity. Stress physiological analysis of local check exposed to 0–300 μM Al under sand culture revealed that 150 μM Al as critical and 200 μM Al as tolerable limit. Increase in Al from 0 to 300 μM reduced total chlorophyll, carotenoids by 74.8 % and 44.7 % respectively and enhanced anthocyanin by 35.3 % whereas LA, SLW and SL have reduced by 81.3%, 21.3 % and 47.8 % respectively. R/S ratio was 51.0 and 13.7 % higher at lower Al levels (50 μM and 100 μM) and photosynthetic, transpiration rate and TDM were 62.5 %, 42.9 % and 78.6 % lower at higher Al (300 μM) as compared to control. TRL, RSA, RDW and RV at higher Al (300 μM) were 92.6 %, 98.7 %, 78.7 and 97.5 % lower over control respectively. Root and shoot Al and PUpE at higher Al (300 μM) was 194.0, 69.2 and 830 % higher whereas PUE decreased to 88.5 % over control. Evaluation of 31 indigenous maize cultivars at 0, 150, and 250 μM Al in sand culture, alongside tolerance scoring and assessment, revealed that Megha-9, Megha-10, and MZM-19 exhibits high Al tolerance, Megha-1, MZM-22, and MZM-42 demonstrated moderate tolerance, whereas Uruapara, Sublgarh, and BRL Para were identified as Al-sensitive. Stress physiological parameters like SDW, TDM, TRL, SL and LA contributed 46.02 % of variability to PC1, whereas A, RV, RSA, anthocyanin and Chlorophyll_b, contributed 13.56 % of variability to PC2. Highest values of CMS, SL, LP, LA, TRL and anthocyanin were recorded in cluster I having sensitive cultivars while highest CMS, SL, LA, LP, TRL and RSA were found in cluster II having moderately tolerant cultivars and highest mean values for TRL, RSA, LP, LA, CMS and SL were recorded in cluster III having highly Al stress tolerant cultivars. The traits viz., A, RV, RSA, anthocyanin and Chlorophyll_b, total chlorophyll and TDM were emanated as physio-morphological for assessing Al toxicity stress tolerance in Maize with high divergence values. Tolerant cultivars showing 63.4 % and 22.4 % higher anthocyanin at 150 μM Al and 250 μM Al than moderately tolerant one in acid soil experiment with increased root Al, shoot Al, root P and shoot P by 42.6 %, 11 %, 95.1 % and 34 % respectively were emerged as promising for novel maize improvement under acid soils of EHR.

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]

Cotton (Gossypium hirsutum L.) has been a valuable economic crop in arid Xinjiang, whose cotton production accounts for 90.2 % of the grand total in China. Low phosphorus (P) bioavailability brings severe restrictions for cotton production in arid regions as a result of P precipitation caused by high soil pH and Ca2+ content. Therefore, how to utilize the biological potential to improve the efficiency of P utilization has become a hotspot for international research.To learn more about P bioavailability in cotton from the perspectives of root morphology, rhizosphere physiology, and mycorrhizal association, especially the synergistic effect of these three under the optimal P input on P bioavailability. A 2-year, split-plot field experiment was conducted consecutively from 2016 to 2017, in which the main plots contained three cotton varieties (XLZ57, XLZ19, and XLZ13) and the subplots were treated with five P levels (0, 75, 150, 300, and 450 kg P 2 O 5 ha−1). Optimal P input (P fertilizer application: 75–150 kg P 2 O 5 ha−1 or soil available P content in topsoil: 11–25 mg kg−1) was found to not only improve the distribution of root system and mycorrhiza in soil but also promote the secretion of protons and alkaline phosphatase in the rhizosphere, leading to higher P uptake and cotton yield. Although high P input (300–450 kg P 2 O 5 ha−1) increased soil available P content, it inhibited root growth, mycorrhizal infection and phosphatase activity, thus reducing P uptake and product. To obtain a relatively high yield (5500–6500 kg ha−1 unginned cotton) and high P accumulation (120–130 kg P 2 O 5 ha−1), an ideotype cotton root/rhizosphere should be characterized by high root length density (4–5 m 1000 cm−3), large hyphal density (15–18 m g−1), and greater exudation of protons and alkaline phosphatase (60–70 μg g−1 h−1) in topsoil, as well as a large microbial P (MBP) value (25–28 mg kg−1).Compared to mycorrhizal symbiosis (reflected by hyphal density), rhizosphere secretion of protons and alkaline phosphatase (rhizosphere physiology) and root length density (architecture) pose greater contributions to higher rhizosphere P availability and cotton P uptake. Moreover, the rhizosphere process and P use efficiency (PUE) of the P-efficient cultivar (XLZ19) were higher compared to the P-inefficient one (XLZ13).The results suggest that maximizing root/rhizosphere efficiency under optimal P input may improve cotton productivity and P uptake efficiency in mulched cotton fertigation systems in arid and semi-arid areas. • Rhizosphere regulation is a key biological way to improve P efficiency in cotton. • Optimal P input construct cotton rhizosphere process and improve P use efficiency. • Rhizosphere physiology and architecture pose greater contributions to P availability. [ABSTRACT FROM AUTHOR]

Upland rice (Oryza sativa) is adapted to strongly phosphorus (P) sorbing soils. The mechanisms underlying P acquisition, however, are not well understood, and models typically underestimate uptake. This complicates root ideotype development and trait‐based selection for further improvement. We present a novel model, which correctly simulates the P uptake by a P‐efficient rice genotype measured over 48 days of growth. The model represents root morphology at the local rhizosphere scale, including root hairs and fine S‐type laterals. It simulates fast‐ and slowly reacting soil P and the P‐solubilizing effect of root‐induced pH changes in the soil. Simulations predict that the zone of pH changes and P solubilization around a root spreads further into the soil than the zone of P depletion. A root needs to place laterals outside its depletion‐ but inside its solubilization zone to maximize P uptake. S‐type laterals, which are short but hairy, appear to be the key root structures to achieve that. Thus, thicker roots facilitate the P uptake by fine lateral roots. Uptake can be enhanced through longer root hairs and greater root length density but was less sensitive to total root length and root class proportions. Summary Statement: Upland rice increases phosphorus uptake in strongly sorbing soils by placing fine S‐type lateral roots inside the solubilization zones of thicker roots. [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.

Inorganic phosphate (Pi) is an essential macronutrient required for many fundamental processes in plants, including photosynthesis and respiration, as well as nucleic acid, protein, and membrane phospholipid synthesis. The huge use of Pi-containing fertilizers in agriculture demonstrates that the soluble Pi levels of most soils are suboptimal for crop growth. This review explores recent advances concerning the understanding of adaptive metabolic processes that plants have evolved to alleviate the negative impact of nutritional Pi deficiency. Plant Pi starvation responses arise from complex signaling pathways that integrate altered gene expression with post-transcriptional and post-translational mechanisms. The resultant remodeling of the transcriptome, proteome, and metabolome enhances the efficiency of root Pi acquisition from the soil, as well as the use of assimilated Pi throughout the plant. We emphasize how the up-regulation of high-affinity Pi transporters and intra- and extracellular Pi scavenging and recycling enzymes, organic acid anion efflux, membrane remodeling, and the remarkable flexibility of plant metabolism and bioenergetics contribute to the survival of Pi-deficient plants. This research field is enabling the development of a broad range of innovative and promising strategies for engineering phosphorus-efficient crops. Such cultivars are urgently needed to reduce inputs of unsustainable and non-renewable Pi fertilizers for maximum agronomic benefit and long-term global food security and ecosystem preservation. [ABSTRACT FROM AUTHOR]

Yield potential of maize having distinct genetic diversity in Eastern Himalayan Region (EHR) hill ecologies is often limited by Al toxicity caused due to soil acidity. Stress physiological analysis of local check exposed to 0-300 μM Al under sand culture revealed that 150 μM Al as critical and 200 μM Al as tolerable limit. Increase in Al from 0 to 300 μM reduced total chlorophyll, carotenoids by 74.8 % and 44.7 % respectively and enhanced anthocyanin by 35.3 % whereas LA, SLW and SL have reduced by 81.3%, 21.3 % and 47.8 % respectively. R/S ratio was 51.0 and 13.7 % higher at lower Al levels (50 μM and 100 μM) and photosynthetic, transpiration rate and TDM were 62.5 %, 42.9 % and 78.6 % lower at higher Al (300 μM) as compared to control. TRL, RSA, RDW and RV at higher Al (300 μM) were 92.6 %, 98.7 %, 78.7 and 97.5 % lower over control respectively. Root and shoot Al and PUpE at higher Al (300 μM) was 194.0, 69.2 and 830 % higher whereas PUE decreased to 88.5 % over control. Evaluation of 31 indigenous maize cultivars at 0, 150, and 250 μM Al in sand culture, alongside tolerance scoring and assessment, revealed that Megha-9, Megha-10, and MZM-19 exhibits high Al tolerance, Megha-1, MZM-22, and MZM-42 demonstrated moderate tolerance, whereas Uruapara, Sublgarh, and BRL Para were identified as Al-sensitive. Stress physiological parameters like SDW, TDM, TRL, SL and LA contributed 46.02 % of variability to PC1, whereas A, RV, RSA, anthocyanin and Chlorophyll_b, contributed 13.56 % of variability to PC2. Highest values of CMS, SL, LP, LA, TRL and anthocyanin were recorded in cluster I having sensitive cultivars while highest CMS, SL, LA, LP, TRL and RSA were found in cluster II having moderately tolerant cultivars and highest mean values for TRL, RSA, LP, LA, CMS and SL were recorded in cluster III having highly Al stress tolerant cultivars. The traits viz., A, RV, RSA, anthocyanin and Chlorophyll_b, total chlorophyll and TDM were emanated as physio-morphological for assessing Al toxicity stress tolerance in Maize with high divergence values. Tolerant cultivars showing 63.4 % and 22.4 % higher anthocyanin at 150 μM Al and 250 μM Al than moderately tolerant one in acid soil experiment with increased root Al, shoot Al, root P and shoot P by 42.6 %, 11 %, 95.1 % and 34 % respectively were emerged as promising for novel maize improvement under acid soils of EHR., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Published by Elsevier Ltd.)

Phosphorus (P) is an essential element and its efficient use is of global importance. This study evaluated the effect of growing potato under legume intercrops on P uptake and use efficiency indices: P harvest index (PHI), P uptake efficiency (PuPE), P partial factor productivity (PPFP) and P partial balance (PPB). The experiment was carried out for four consecutive seasons with treatments comprising potato cultivated under legume intercrops: none (T1), dolichos (Lablab purpureus L) (T2), peas (Pisum sativum L) (T3) and beans (Phaseolus vulgaris L) (T4). Across the seasons, the mean haulm P uptake for T2 (6.7 kg P ha−1), T4 (5.5) and T3 (4.5) were 6%, 23% and 36% lower than that observed in T1 (7.1 kg P ha−1), respectively. On the other hand, tuber P uptake was highest in T1 (21.8 kg P ha−1) and T2 (21.3 kg P ha−1) and were significantly higher than 13.2 kg P ha−1 in T3 and 15.1 kg P ha−1 in T4. This had a profound effect on PuPE, which was equally highest in T1 (0.26 kg total P uptake kg−1 P supply) and T2 (0.25) and lowest in T3 (0.16) and T4 (0.18). Similarly, PPFP, PHI and PPB followed a similar trend, with highest values in T1 (57 kg tuber dry matter yield kg−1 P supply, 76.4 kg tuber P uptake kg−1 total plant's P uptake and 0.20 kg tuber P uptake kg−1 P supply, respectively). Among the tested legume intercrops, dolichos competed least for P with the main crop (potato) hence it can be integrated into potato-based cropping systems without compromising potato tuber yield. [ABSTRACT FROM AUTHOR]

Limited phosphorus availability in the soil is one of the major constraints to the growth and productivity of rice across Asian, African and South American countries, where 50% of the rice is grown under rain-fed systems on poor and problematic soils. With an aim to determine novel alleles for enhanced phosphorus uptake efficiency in wild species germplasm of rice Oryza rufipogon, we investigated phosphorus uptake1 (Pup1) locus with 11 previously reported SSR markers and sequence characterized the phosphorus-starvation tolerance 1 (PSTOL1) gene. In the present study, we screened 182 accessions of O. rufipogon along with Vandana as a positive control with SSR markers. From the analysis, it was inferred that all of the O. rufipogon accessions undertaken in this study had an insertion of 90 kb region, including Pup1-K46, a diagnostic marker for PSTOL1, however, it was absent among O. sativa cv. PR114, PR121, and PR122. The complete PSTOL1 gene was also sequenced in 67 representative accessions of O. rufipogon and Vandana as a positive control. From comparative sequence analysis, 53 mutations (52 SNPs and 1 nonsense mutation) were found in the PSTOL1 coding region, of which 28 were missense mutations and 10 corresponded to changes in the amino acid polarity. These 53 mutations correspond to 17 haplotypes, of these 6 were shared and 11 were scored only once. A major shared haplotype was observed among 44 accessions of O. rufipogon along with Vandana and Kasalath. Out of 17 haplotypes, accessions representing 8 haplotypes were grown under the phosphorus-deficient conditions in hydroponics for 60 days. Significant differences were observed in the root length and weight among all the genotypes when grown under phosphorus deficiency conditions as compared to the phosphorus sufficient conditions. The O. rufipogon accession IRGC 106506 from Laos performed significantly better, with 2.5 times higher root weight and phosphorus content as compared to the positive control Vandana. In terms of phosphorus uptake efficiency, the O. rufipogon accessions IRGC 104639, 104712, and 105569 also showed nearly two times higher phosphorus content than Vandana. Thus, these O. rufipogon accessions could be used as the potential donor for improving phosphorus uptake efficiency of elite rice cultivars.

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.

Drought and low phosphorus (P) availability are major limitations for rainfed rice production. Crop roots are important for soil resource acquisition and tolerance to P and water limitations. Two pot and two field trials were conducted to evaluate architectural root responses of contrasting rice varieties to combinations of different levels of P (deficient to non-limiting) and water availability (water stressed to submergence) and to identify the interactions with different varieties. Root development was then related to drought and/or low P tolerance. Although shoot and root growth responded more to P than to water availability, architectural root responses to water were much more prominent than responses to P availability. Reduced water availability decreased nodal thickness and increased secondary root branching, both factors partially enhancing P uptake efficiency and even overcoming a decreased root:shoot ratio under reduced water availability. In contrast to root thickness and secondary branching, basal lateral root density was strongly determined by variety and was related to enhanced P uptake. Reduced water availability induces root modifications which—apart from enhancing drought resilience—also affect P uptake efficiency. Future research on rice roots and nutrient uptake may hence take into account the large effects of water on root development.

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Limited phosphorus availability in the soil is one of the major constraints to the growth and productivity of rice across Asian, African and South American countries, where 50% of the rice is grown under rain-fed systems on poor and problematic soils. With an aim to determine novel alleles for enhanced phosphorus uptake efficiency in wild species germplasm of rice Oryza rufipogon, we investigated phosphorus uptake1 (Pup1) locus with 11 previously reported SSR markers and sequence characterized the phosphorus-starvation tolerance 1 (PSTOL1) gene. In the present study, we screened 182 accessions of O. rufipogon along with Vandana as a positive control with SSR markers. From the analysis, it was inferred that all of the O. rufipogon accessions undertaken in this study had an insertion of 90 kb region, including Pup1-K46, a diagnostic marker for PSTOL1, however, it was absent among O. sativa cv. PR114, PR121, and PR122. The complete PSTOL1 gene was also sequenced in 67 representative accessions of O. rufipogon and Vandana as a positive control. From comparative sequence analysis, 53 mutations (52 SNPs and 1 nonsense mutation) were found in the PSTOL1 coding region, of which 28 were missense mutations and 10 corresponded to changes in the amino acid polarity. These 53 mutations correspond to 17 haplotypes, of these 6 were shared and 11 were scored only once. A major shared haplotype was observed among 44 accessions of O. rufipogon along with Vandana and Kasalath. Out of 17 haplotypes, accessions representing 8 haplotypes were grown under the phosphorus-deficient conditions in hydroponics for 60 days. Significant differences were observed in the root length and weight among all the genotypes when grown under phosphorus deficiency conditions as compared to the phosphorus sufficient conditions. The O. rufipogon accession IRGC 106506 from Laos performed significantly better, with 2.5 times higher root weight and phosphorus content as compared to the positive control Vandana. In terms of phosphorus uptake efficiency, the O. rufipogon accessions IRGC 104639, 104712, and 105569 also showed nearly two times higher phosphorus content than Vandana. Thus, these O. rufipogon accessions could be used as the potential donor for improving phosphorus uptake efficiency of elite rice cultivars. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency and aluminium (Al) phytotoxicity are major limitations for crop yield in acid soils. To ameliorate such limitations, agricultural management includes application of lime and P fertilisers, and the use of Al-tolerant plant genotypes. The mechanisms of Al tolerance and P efficiency may be closely related through strategies that decrease the toxicity of the Al3+ ion and increase P availability in soils. However, the effects of soils with high Al saturation on P acquisition by wheat have been little studied under field conditions. The aim of this work was to study Al-P interactions on wheat genotypes of contrasting Al tolerance when grown under field conditions in a volcanic soil with high Al saturation (32%) and low pH (5.0). A field-plot experiment was performed with winter wheat genotypes, two Al-tolerant (TCRB14 and TINB14) and one Al-sensitive (STKI14), with application of 0, 44 and 88 kg P ha-1. At the end of tillering and after physiological maturity (90 and 210 days after sowing), plants were harvested and yield and P and Al concentrations in shoots and roots were measured. Soil acid phosphatase, root arbuscular mycorrhizal (AM) colonisation, AM spore number and soil glomalin were determined. Shoot and root production and P uptake were higher in Al-tolerant genotypes than the sensitive genotype. In addition, root AM colonisation and soil acid phosphatase activity were also higher in tolerant genotypes. By contrast, Al concentration in shoots and roots was higher in the sensitive genotype with a concomitant decrease in P concentration. Grain yield of Al-tolerant genotypes was higher than of the Al-sensitive genotype with and without P fertiliser. Overall, the Al-tolerant genotypes were more effective at P acquisition from soil as well as from P fertiliser added, suggesting that plant traits such as Al tolerance, P efficiency, and AM colonisation potential co-operate in overcoming adverse acid soil conditions. [ABSTRACT FROM AUTHOR]

Adding mulch biomass prior to crop seeding may improve production of tropical soil. We evaluated the response of four bean (Phaseolus vulgaris L.) genotypes to the addition of mulch biomass from Tithonia diversifolia (Hemsl.) Gray and Cajanus cajan L. Millsp. The addition of mulch did not result in significant differences (p < 0.05) in soil characteristics when compared to a control (no mulch addition) except for soil potassium (K), which was significantly greater (p < 0.05) in the T. diversifolia mulch biomass treatment. Bean yield and shoot biomass were significantly greater (p < 0.05) in the mulch biomass treatments compared to the control (no biomass added). In these treatments, Phosphorus (P)-efficient bean genotypes had a significantly greater (p < 0.05) yield and shoot biomass. Bean shoot nutrient concentrations were significantly different (p < 0.05) between mulch biomass treatments and between bean genotypes (P, K and magnesium (Mg) only). Phosphorus utilization and uptake efficiencies were significantly different (p < 0.05) between mulch biomass treatments and between bean genotypes. Bean root biomass was not significantly different (p < 0.05) between mulch biomass treatments, but was significantly different (p < 0.05) between bean genotypes. The number of root nodules was significantly greater (p < 0.05) in the T. diversifolia mulch biomass treatment and was significantly different between bean genotypes.

Intensive use of phosphorus (P) in agriculture has raised concerns about its sustainability due to potential resource scarcity and its non-judicious use which has led to serious environmental pollution. Plants possess a number of adaptive mechanisms to cope with P stress leading to changes at morphological, physiological, biochemical and molecular levels. A comprehensive understanding of these adaptive responses is required to improve P uptake efficiency, partitioning and utilization, together with other agronomic approaches, which would result in meeting the sustainability challenge of P delivery to crops. The present article briefly covers various plant responses to P stress and molecular strategies that could be used to develop plants efficient in P acquisition. [ABSTRACT FROM AUTHOR]

It has been documented that arbuscular mycorrhizal (AM) symbiosis can enhance plant tolerance to heavy metal (HM) contamination. However, variations among different AM fungal species for their ability to make their host HM tolerant have rarely been examined. This study therefore aimed to compare the cadmium (Cd) tolerance of plants colonized by different AM fungi, and to test the relationship between phosphorus (P) uptake efficiency and the Cd tolerance of the symbiotic associations.Lotus japonicusL. inoculated with each of three different AM fungi,Gigaspora margaritaBecker & Hall,Acaulospora longulaSpain & Schenck andRhizophagus irregularisBlaszk., Wubet, Renker & Buscot, was grown under three Cd addition levels (0, 5 and 50 mg kg−1) in a pot experiment, and growth, P and Cd uptake of the plants were examined. Significant linear correlations were observed between growth, P-uptake and Cd-uptake of the plant.R. irregulariswas more resistant to Cd contamination compared with the other two AM fungal species in terms of higher colonization rate, P uptake efficiency and better plant growth, even in a Cd contaminated environment. Symbiotic P uptake might determine the Cd tolerance of mycorrhizal plants, and it could possibly serve as an important criterion for screening efficient AM fungal species/strains for bioremediation of HM-contaminated environments. [ABSTRACT FROM PUBLISHER]

Background and aims: The Serengeti grassland is characterized by antiparallel gradients of soil phosphorus (P) and precipitation. We hypothesized that grasses associate with arbuscular mycorrhizal (AM) fungi to ameliorate water stress and improve nutrient acquisition; and, that geographic patterns in AM fungal abundance relate to nutrient and water limitation of host plants. Methods: We conducted a factorial experiment to uncouple the interacting effects of soil type, P, and water availability on AM fungal abundance. Maize was grown in pots of soil collected from three locations across the natural gradients. Full factorial treatments of +/− P fertilization and high/low water were administered to all three soils. Results: Abundance of AM hyphae in soil was reduced by fertilization in high-P soil and increased with fertilization in low-P soil. Phosphorus uptake efficiency of mycorrhizas was greatest in low-P soil. Water-limited plants grown in arid region soil allocated relatively more biomass to AM fungi. Conclusions: The formation of AM fungi in each soil was most strongly linked to the most limiting belowground resource. Interactions among soil properties, water availability and variation in the community composition of AM fungi are likely to influence the abundance and function of AM symbioses the Serengeti. [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]

Information regarding the characteristics that affect P-uptake capacity may assist in the selection of more adapted potato ( Solanum tuberosum L.) cultivars and more adequate fertilization management for each cultivar. This study evaluated the P-uptake capacity of potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial) grown under P-deficient (2 mg L −1 ) or P-sufficient (31 mg L −1 ) conditions in nutrient solution and related it to physiological parameters of uptake and morphological root characteristics. When the plants were 24 days old, they were subjected to a P-uptake kinetics study. The length and surface area of roots and the uptake kinetic parameters ( I max , K m , and C min ) varied among potato cultivars. Phosphorus-deficient potato plants had an approximately 60% smaller root surface area and an increase of 86% in the I max and net P influx compared with the plants in P-sufficient conditions. However, these modifications in P uptake kinetics can do not influence P acquisition in the soil environment due to very limited P diffusion. The amount of P accumulated by plants grown under P-deficient conditions was directly related to the root length and surface area; a greater root surface, as demonstrated by the Asterix cultivar, is the most important factor for achieving a greater P-uptake capacity. Under P-sufficient conditions, potato cultivars such as Markies and Mondial showed a balance between morphological root characteristics (medium/large length and surface area) and physiological parameters (medium/high I max values and net P influx) and had a greater P-uptake capacity. However, under field conditions, the responses to P deficiency may be different due to the very limited diffusion of P in the soil and because plants can use additional mechanisms to improve their P uptake from the soil. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency is a major yield-limiting constraint in wheat production. This situation is further aggravated by the depleting supply of P resources. The ability of wheat to adapt to low P soil is inferior to some wild grass species. In order to locate high P efficiency genes on specific chromosomes of wheat relatives, 107 wheat alien chromosome addition lines were used to investigate P efficiency at the seedling stage. The results showed that introgression of alien chromosomes affected the P uptake and utilization efficiency. which resulted in altered P efficiency. Nine addition lines conferred high P efficiency. seven addition lines conferred high P uptake efficiency, and 39 addition lines conferred high P utilization efficiency. The high P addition lines of selected did not depend on genome type or homologous group. The addition lines with high P efficiency could be used for breeding high P efficiency wheat cultivars through wild hybridization. [ABSTRACT FROM AUTHOR]

Two rice genotypes, JX17 (Oryza sativa ssp. japonica) and ZYQ8 (Oryza sativa ssp. indica), which had been the parents of the 127-line double haploid (DH) population for construction of molecular linkage map, were chosen to study their response to low phosphorus (P) stress. The results indicated that JX17 had advantages over ZYQ8 on some traits associated with phosphorus uptake efficiency, such as root dry weight, root-exuded acid phosphatase activity, root-exuded organic acids and proton. Consequently, JX17 had higher relative total dry weight and was regarded as the non-sensitive genotype to low phosphorus stress. Physiological response of the two genotypes to P deficiency was studied in monoculture and in mixed culture. The results showed that, compared with monoculture, JX17 absorbed more P and had higher biomass in mixed culture condition under P stress. ZYQ8, by contrast, suffered from P stress to a much greater extent, with lower P uptake and biomass. JX17 had a higher P uptake rate expressed as P amount per root length which is suggested to be the main reason for its insensitivity to low P stress. [ABSTRACT FROM AUTHOR]

• Stem length was significantly reduced at 6 mg P L−1 only. • Biomass, flowering and branching were strongly reduced at 6 mg L−1. • Plant quality was optimal at 0.25-0.30 % (chrysanthemum) and 0.30-0.35 % (poinsettia) P. • P efficiency (PE) was strongly related to internal P utilization efficiency (PUE). • Chrysanthemum had higher PUE and PE than poinsettia at low P levels. Better synchronization of plant-available phosphorus (P) with crop P requirement is required to reduce P losses to the environment and to improve resource-efficiency of the exploitation of non-renewable phosphate rock. In horticultural plant production, a restricted availability of P may limit stem length and improve compactness, which are desirable characters for many ornamental plants. In the present study, we investigated the effect of reduced availability of P on plant quality, biomass production and phosphorus efficiency of poinsettia (Euphorbia pulcherrima cv. 'Mira Red') and chrysanthemum (Chrysanthemum × morifolium cv. 'Breeze Cassis'). Five P concentrations (6, 12, 18, 24 or 48 mg L−1) were applied as starter P in the peat-based potting substrate as well as in the nutrient solution given during the experiment. Stem length of both plant species was strongly restricted at 6 mg P L−1 but was not significantly affected by higher P levels. For poinsettia, the optimum bract diameter was obtained at 18 mg P L−1. For maximum shoot dry biomass, branching and plant diameter, however, 24 mg L−1 was needed. Optimal plant diameter and shoot biomass of chrysanthemum was obtained at 18 mg P L−1 while 24 mg L−1 was required for maximum flower number. Increasing the P supply to 48 mg L-1 did not improve shoot dry matter, branching or flowering of either species, but induced luxury uptake of P. Total shoot P uptake increased linearly over the P fertilizer range tested. For optimal plant biomass combined with optimal ornamental quality, shoot P concentrations at 90 DAP was in the range of 0.30-0.35 % for poinsettia and 0.25-0.30 % for chrysanthemum. Chrysanthemum showed a higher phosphorus efficiency than poinsettia at low P levels, mainly related to a higher internal P utilization efficiency. The P acquisition efficiency was in the range of 55–60 % for both species, and was not significantly affected by the total amount of P applied. In conclusion, with the P fertilization strategy used, P restriction could not be used for plant height restriction of poinsettia "Mira Red" or chrysanthemum "Breeze Cassis" without negative effects on plant quality. However, P fertilization could be markedly reduced without negative effects on plant growth and development, improving phosphorus efficiency and recovery. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Highlight: Root plasticity to water availability affects the P uptake efficiency of rice by modifying root architecture. Genotypic variation in root architecture can explain tolerance to low P and water stress. Drought and low phosphorus (P) availability are major limitations for rainfed rice production. Crop roots are important for soil resource acquisition and tolerance to P and water limitations. Two pot and two field trials were conducted to evaluate architectural root responses of contrasting rice varieties to combinations of different levels of P (deficient to non-limiting) and water availability (water stressed to submergence) and to identify the interactions with different varieties. Root development was then related to drought and/or low P tolerance. Although shoot and root growth responded more to P than to water availability, architectural root responses to water were much more prominent than responses to P availability. Reduced water availability decreased nodal thickness and increased secondary root branching, both factors partially enhancing P uptake efficiency and even overcoming a decreased root:shoot ratio under reduced water availability. In contrast to root thickness and secondary branching, basal lateral root density was strongly determined by variety and was related to enhanced P uptake. Reduced water availability induces root modifications which—apart from enhancing drought resilience—also affect P uptake efficiency. Future research on rice roots and nutrient uptake may hence take into account the large effects of water on root development. [ABSTRACT FROM AUTHOR]