Agronomy

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18 pages, 4414 KiB

Open AccessArticle

Effects of Apatite Concentrate in Combination with Phosphate-Solubilizing Microorganisms on the Yield of Ryegrass Cultivar Izorskiy

by Tatiana A. Timofeeva, Vladimir K. Chebotar, Dmitriy V. Demidov, Sofia E. Gaidukova, Irina V. Yakovleva and Anastasia M. Kamionskaya

Agronomy 2023, 13(6), 1568; https://doi.org/10.3390/agronomy13061568 - 8 Jun 2023

Cited by 5 | Viewed by 1926

Abstract

Soil microorganisms play a vital role in increasing the availability of phosphorus (P) for plants through mineralization of organic P and solubilization of precipitated P compounds. In this two-year study, we analyzed several P-solubilizing microorganisms (PSMs) of the genus Bacillus and their consortiums [...] Read more.

Soil microorganisms play a vital role in increasing the availability of phosphorus (P) for plants through mineralization of organic P and solubilization of precipitated P compounds. In this two-year study, we analyzed several P-solubilizing microorganisms (PSMs) of the genus Bacillus and their consortiums for the ability to release soluble P from apatite concentrates of various grinding degrees using ryegrass (Lolium multiflorum Lam.) as a model plant. The effects were accessed by analyzing plant growth and nutrient assimilation. The greatest effect on root system development and plant biomass accumulation (dry weight) was observed for the apatite concentrate of standard grinding in combination with Bacillus megaterium BI14 and Bacillus subtilis BI2 and Bacillus velezensis BS89 strains. Although the introduction of apatite concentrates led to an increase in the content of total strontium in soil, the levels of strontium did not exceed the maximum allowable concentration, and the accumulation of mobile strontium by plants was unchanged; importantly, the use of tested PSMs led to a decrease in the strontium content in the green biomass of ryegrass. Our results indicate that biologized apatite concentrates in combination with PSMs represent promising fertilizers that can provide a source of soluble P to be readily assimilated by plants. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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15 pages, 797 KiB

Open AccessArticle

Identification, Characterization, and Growth-Promoting Effects of Bacterial Endophytes Isolated from Okra (Abelmoschus esculentus L.)

by Ahsanul Salehin, Sakiko Yamane, Makoto Ueno and Shohei Hayashi

Agronomy 2023, 13(5), 1226; https://doi.org/10.3390/agronomy13051226 - 26 Apr 2023

Cited by 1 | Viewed by 2580

Abstract

Microorganisms colonize plant roots and exhibit plant growth promotion properties, therefore functioning as biofertilizers. To effectively use plant growth-promoting rhizobacteria, understanding their colonizing behavior and ability to compete with co-existing bacteria is essential. In this study, 12 endophytic bacterial strains belonging to seven [...] Read more.

Microorganisms colonize plant roots and exhibit plant growth promotion properties, therefore functioning as biofertilizers. To effectively use plant growth-promoting rhizobacteria, understanding their colonizing behavior and ability to compete with co-existing bacteria is essential. In this study, 12 endophytic bacterial strains belonging to seven genera in four classes with 99–100% homology were isolated from the roots of okra plants (Abelmoschus esculentus L.). Four isolates (Okhm3, Okhm5-4, Okhm10, and Okhm11) were inoculated on okra seeds and their effects on plant growth and colonization with single and mixed inoculations were evaluated. Okra was cultivated using sterilized vermiculite, and the growth parameters and colonization were measured 30 d after seed inoculation. All strains exhibited plant growth promotion traits that could improve okra plant growth in pot culture experiments. Notably, Okhm5-4 and Okhm10 strains (belonging to the Ensifer and Pseudomonas genera) revealed the highest growth-promoting effects on okra plants. Both strains were detected in the endosphere and rhizosphere of okra plants. Okhm10 and Okhm5-4, with lower colonization than Okhm3, showed better growth than Okhm3. Therefore, the colonization potential does not determine the growth-promoting effects. While Okhm3 populations remained stable in both inoculation conditions, the population level of other strains decreased in the mixed inoculation. This study showed bacterial endophytes isolated from Okra can be exploited as bio-fertilizers for sustainable agriculture systems. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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14 pages, 1568 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Biofertilization with PGP Bacteria Improve Strawberry Plant Performance under Sub-Optimum Phosphorus Fertilization

by Pedro Valle-Romero, Jesús V. García-López, Susana Redondo-Gómez, Noris J. Flores-Duarte, Ignacio D. Rodríguez-Llorente, Yanina Lorena Idaszkin, Eloisa Pajuelo and Enrique Mateos-Naranjo

Agronomy 2023, 13(2), 335; https://doi.org/10.3390/agronomy13020335 - 24 Jan 2023

Cited by 13 | Viewed by 2839

Abstract

Biofertilization with plant growth-promoting bacteria (PGPB) could optimize chemical fertilization for strawberry crop cultivation. A greenhouse study was arranged to assess the impact of an isolated PGPB consortium from halophytes on strawberry development, physiological traits, and nutritional balance subjected to two phosphorus fertilization [...] Read more.

Biofertilization with plant growth-promoting bacteria (PGPB) could optimize chemical fertilization for strawberry crop cultivation. A greenhouse study was arranged to assess the impact of an isolated PGPB consortium from halophytes on strawberry development, physiological traits, and nutritional balance subjected to two phosphorus fertilization limitation treatments (with and without insoluble phosphorus form application). Biofertilization had a positive effect on strawberry development. Thus, shoot and root biomass was c. 20 and 32% higher in inoculated plants grown with insoluble phosphorus. This effect was mediated by a positive bacterial impact on plant carbon absorption capacity and water use efficiency, through a reduction in CO₂ diffusional and biochemical photosynthesis limitation. Thus, net photosynthetic rate and intrinsic water use efficiency showed increments of 21–56% and 14–37%, respectively. In addition, inoculation led to a better efficiency of the plant photochemical apparatus, as indicated by the invariable higher PSII photochemistry parameters. Furthermore, these effects correlated with improved nutritional balance of phosphorus and nitrogen, which was directly related to the beneficial impact on carbon metabolism and, consequently, on strawberries’ growth. In conclusion, we can recommend the biofertilization based on PGPB for achieving more efficient strawberry P fertilization management practices, providing high efficiency in yields. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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21 pages, 10355 KiB

Open AccessArticle

Combined Application of Trichoderma harzianum and Paclobutrazol to Control Root Rot Disease Caused by Rhizoctonia solani of Tomato Seedlings

by Tarek A. Shalaby, Naglaa Taha, Hossam S. El-Beltagi and Hassan El-Ramady

Agronomy 2022, 12(12), 3186; https://doi.org/10.3390/agronomy12123186 - 15 Dec 2022

Cited by 9 | Viewed by 2346

Abstract

Many root diseases can cause serious damage to tomato (Solanum lycopersicum L.) production during the seedling growth period, particularly Rhizoctonia solani, Pythium spp., and Alternaria spp. Paclobutrazol (PBZ) has proved to reduce the damage of the Alternaria blight disease on tomato [...] Read more.

Many root diseases can cause serious damage to tomato (Solanum lycopersicum L.) production during the seedling growth period, particularly Rhizoctonia solani, Pythium spp., and Alternaria spp. Paclobutrazol (PBZ) has proved to reduce the damage of the Alternaria blight disease on tomato seedlings. The present investigation was designated to evaluate the growth of infected tomato seedlings with R. solani under applications of Trichoderma harzianum alone, PBZ alone, both PBZ and T. harzianum, and comparing with applied fungicide. PBZ enhanced the chlorophyll system in tomato seedlings, enzymatic antioxidants, and the total antioxidants, besides the vegetative parameters. The combined application of both PBZ and Trichoderma significantly improved growth parameters, decreased the damping off percent of R. solani, as well as increased the enzymatic antioxidants and the total antioxidants of tomato seedlings. It was found that applying 100 mg L⁻¹ PBZ did not affect the effectiveness of the biocontrol agent of T. harzianum. The images of the scanning electron microscope (SEM) confirm that PBZ showed twisting, shrinking, and collapsing of lysis and hyphae in cultures of R. solani. This is the first report that confirms the biochemical control of R. solani on tomato seedlings using the combined application of PBZ and T. harzianum. Further studies are still needed to test more Trichoderma species and different phytopathogens. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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14 pages, 4005 KiB

Open AccessArticle

Effect of Rhizospheric Fungus on Biological Control of Root Rot (Fusarium equiseti) Disease of Saposhnikovia divaricata

by Zhongming Han, Yi Cui, Yan Wang, Yunhe Wang, Zhuo Sun, Mei Han and Limin Yang

Agronomy 2022, 12(11), 2906; https://doi.org/10.3390/agronomy12112906 - 21 Nov 2022

Cited by 8 | Viewed by 2182

Abstract

Saposhnikovia divaricata is a high-demand medicinal plant containing various bioactive metabolites (e.g., chromone). However, root rot disease leads to a dramatic reduction in the yield and quality of S. divaricata. The use of rhizospheric microorganisms is one of the best strategies for [...] Read more.

Saposhnikovia divaricata is a high-demand medicinal plant containing various bioactive metabolites (e.g., chromone). However, root rot disease leads to a dramatic reduction in the yield and quality of S. divaricata. The use of rhizospheric microorganisms is one of the best strategies for biological control. In this study, a total of 104 fungi isolated from the rhizospheric soil of S. divaricata plants were examined for their different antifungal properties. Subsequently, strain MR-57 was selected as a potential stock for biocontrol due to its broad-spectrum antagonistic activity against pathogens, including F. equiseti. Based on the analysis of morphological properties and rDNA internal transcribed spacers (ITSs), strain MR-57 was identified as Acrophialophora jodhpurensis (GenBank No. OK287150.1), a newly recorded species for China. In an in vitro antifungal assay, the culture filtrate of strain MR-57 significantly reduced the conidial germination rate and induced alterations in the mycelia morphology of F. equiseti, such as deformation and degradation. To assess the antifungal efficacy of MR-57 against root rot disease and the properties promoting the growth of S. divaricata, pot experiments were performed under natural outdoor conditions. The results indicated that co-inoculation with MR-57 delayed the occurrence of S. divaricata root rot and showed a control efficacy of 65.41% (p < 0.05) based on the measurement of suppressed disease lesions. Additionally, MR-57 successfully colonized and formed a stable population in the soil in which S. divaricata was grown, and it exhibited a consistently positive effect on the promotion of the growth of S. divaricata plants. In short, Acr. jodhpurensis MR-57 could be considered for the development of a potential biocontrol agent for the management of S. divaricata root rot caused by F. equiseti. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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15 pages, 627 KiB

Open AccessArticle

Combined Application of Inorganic and Organic Phosphorous with Inoculation of Phosphorus Solubilizing Bacteria Improved Productivity, Grain Quality and Net Economic Returns of Pearl Millet (Pennisetum glaucum [L.] R. Br.)

by Abdul Majeed, Muhammad Farooq, Muhammad Naveed and Mubshar Hussain

Agronomy 2022, 12(10), 2412; https://doi.org/10.3390/agronomy12102412 - 5 Oct 2022

Cited by 14 | Viewed by 2273

Abstract

Pearl millet (Pennisetum glaucum [L.] R. Br.) is a climate-smart cereal crop for environments prone to drought and heat stresses. Pearl millet is cultivated in Pakistan on marginal soils with phosphorus (P) deficiency, which significantly decreases its productivity. Moreover, P fixation in [...] Read more.

Pearl millet (Pennisetum glaucum [L.] R. Br.) is a climate-smart cereal crop for environments prone to drought and heat stresses. Pearl millet is cultivated in Pakistan on marginal soils with phosphorus (P) deficiency, which significantly decreases its productivity. Moreover, P fixation in the country’s calcareous soils is another major constraint which requires attention. P solubilizing bacteria (PSB) have the potential to improve P availability in the soil. However, the potential of PSB in improving P availability in soil and pearl millet yield has been rarely tested in Pakistan. Therefore, this 2-year field study explored the role of combined application of organic and inorganic P sources along with PSB (i.e., Bacillus sp. MN54) inoculation to improve yield-related traits, P use efficiency (PUE), net economic returns and grain quality of pearl millet grown under semi-arid climatic conditions. Phosphorus was applied through inorganic sources, organic sources (farmyard manure) and 50% inorganic sources + 50% organic sources with or without PSB inoculation. In control treatment, pearl millet was grown without P application. The individual and combined application of P from different sources and PSB inoculation significantly improved yield-related traits and PUE of pearl millet. The highest grain yield was observed with combined (50% inorganic + 50% organic) application of P with PSB inoculation. The same treatments resulted in higher iron, zinc, protein and P contents in the grains during both years. Likewise, P application through organic and inorganic sources combined with PSB inoculation improved soil bulk density, fertility and microbial population during both years. The highest economic returns and benefit–cost ratio was recorded for combined P application (50% inorganic + 50% organic) and PSB inoculation. In crux, the combined application of organic and inorganic P fertilizers along with PSB (Bacillus sp. MN54) inoculation seemed a feasible approach to enhance productivity, grain quality and net economic returns of pearl millet. Therefore, it is recommended that P should be applied through both organic and inorganic sources combined with PSB inoculation to improve P availability and productivity of pearl millet in Pakistan. The current study has explored the potential of combined P application through organic and inorganic sources along with PSB inoculation. Future studies should focus on the determination of mobilized P with the application of PSB. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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22 pages, 3510 KiB

Open AccessArticle

Changes in Soil Properties, Bacterial Communities and Wheat Roots Responding to Subsoiling in South Loess Plateau of China

by Hanbo Wang, Dasheng Zhang, Jiuxing He, Lijuan Wang, Jiameng Ren, Shuantang Zhang, Wenbo Bai, Jiqing Song, Guohua Lv and Jiusheng Li

Agronomy 2022, 12(10), 2288; https://doi.org/10.3390/agronomy12102288 - 23 Sep 2022

Cited by 5 | Viewed by 2224

Abstract

This study was carried out to investigate effects of subsoiling on the diversity and composition of the bacterial community in a wheat–maize rotation field in the Guanzhong area of Shaanxi Province, China. After the wheat harvest, surface soil samples were collected under two [...] Read more.

This study was carried out to investigate effects of subsoiling on the diversity and composition of the bacterial community in a wheat–maize rotation field in the Guanzhong area of Shaanxi Province, China. After the wheat harvest, surface soil samples were collected under two tillage methods (single rotary tillage (RT) and subsoiling + rotary tillage (ST)) to perform high-throughput sequencing and bioinformatics analysis. Soil properties and root length density (RLD) of winter wheat at booting and flowering stages were also studied. Results showed that ST treatment significantly raised the water storage, organic carbon and total nitrogen contents of deep soil (>40 cm), and notably increased the total soil pH, ammonium nitrogen content and RLD in the tillage layer from 0–70 cm at booting stage and 0~100 cm at flowering stage, but the residual nitrate nitrogen significantly decreased by 17.74%. Compared with RT, soil bacterial richness and diversity in the 10~20 cm layer of ST treatment showed a significantly decreased trend. The relative abundances of GAL15, Actinobacteria, Nitrospirae, Rhizobiales, Burkholderiales, Pseudomonas and Serratia in the 10–20 cm layer were remarkably increased in ST. Principal Component Analysis (PCA) and Redundancy Analysis (RDA) results showed that surface soil pH, ammonium nitrogen and nitrate nitrogen contents have the strongest effect on the bacterial structure. In addition, there were positive correlations between the RLD and the relative abundances of Rhizobiales, Burkholderiales, Pseudomonas and the ammonium nitrogen content. In conclusion, although subsoiling was not conducive to improving soil bacterial community richness and diversity, it significantly increased soil beneficial bacteria (biological nitrogen-fixing bacteria, ammonifying bacteria, nitrobacteria) abundances, reduced the nitrogen loss caused by denitrifying bacteria, promoted earlier root development and improved the plant utilization ratio of soil nutrients. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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14 pages, 1175 KiB

Open AccessEditor’s ChoiceArticle

Synergistic Effect of Plant-Growth-Promoting Rhizobacteria Improves Strawberry Growth and Flowering with Soil Salinization and Increased Atmospheric CO₂ Levels and Temperature Conditions

by Susana Redondo-Gómez, Jesús V. García-López, Jennifer Mesa-Marín, Eloísa Pajuelo, Ignacio D. Rodriguez-Llorente and Enrique Mateos-Naranjo

Agronomy 2022, 12(9), 2082; https://doi.org/10.3390/agronomy12092082 - 31 Aug 2022

Cited by 17 | Viewed by 2914

Abstract

Biofertilization with plant-growth-promoting rhizobacteria (PGPR) can positively affect the growth and health of host plants and reinforce their tolerance of stressors. Here, we investigate the use of isolated PGPR consortia from halophytes to improve strawberry growth and flowering performance under saline and elevated [...] Read more.

Biofertilization with plant-growth-promoting rhizobacteria (PGPR) can positively affect the growth and health of host plants and reinforce their tolerance of stressors. Here, we investigate the use of isolated PGPR consortia from halophytes to improve strawberry growth and flowering performance under saline and elevated CO₂ and temperature conditions. Growth, flower bud production, and the photosynthetic apparatus response were determined in strawberry plants grown at 0 and 85 mmol L⁻¹ NaCl and in two atmospheric CO₂-temperature combinations (400/700 ppm and 25/+4 °C, respectively). Biofertilization improved strawberry plant growth and flower bud production, independently of salinity conditions, at ambient CO₂ and 25 °C, while bacterial inoculation only had a positive effect on plant growth in the presence of salt in high CO₂ and at +4 °C. Biofertilizers 1 and 3 generated the largest biomass of strawberries at 400 ppm CO₂ and 0 and 85 mmol L⁻¹ NaCl, respectively, while biofertilizer 1 did so in the presence of salt and in an atmosphere enriched with CO₂ and at +4 °C. The effect of the consortia was mediated by bacterial strain PGP properties, rather than by an improvement in the photosynthetic rate of the plants. Furthermore, biofertilizers 1 and 2 increased the number of flower buds in the absence of salt, while biofertilizers 3 and 4 did so for salt-inoculated plants at 400 ppm CO₂ and at 25 °C. There was no effect of inoculation on flower bud production of plants grown at high CO₂ and at +4 °C. Finally, we concluded that the effect of bacterial inoculation on strawberry growth and flowering depended on the type of bacterial strain and growth conditions. This highlights the importance of developing studies considering stress interaction to assess the real potential of biofertilizers. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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13 pages, 2741 KiB

Open AccessArticle

Silicon Fertilizer and Microbial Agents Changed the Bacterial Community in the Consecutive Replant Soil of Lilies

by Yanlin Yu, Lipeng Zhang, Yuanpeng Li, Lei Hou, Hongyu Yang and Guiying Shi

Agronomy 2022, 12(7), 1530; https://doi.org/10.3390/agronomy12071530 - 25 Jun 2022

Cited by 11 | Viewed by 2345

Abstract

Crop replanting leads to soil degradation and soil productivity reduction, which is a challenge for sustainable agricultural development. We previously found that silicon fertilizers combined with additional microbial agents are an effective means to alleviate problems that occur in a variety of Chinese [...] Read more.

Crop replanting leads to soil degradation and soil productivity reduction, which is a challenge for sustainable agricultural development. We previously found that silicon fertilizers combined with additional microbial agents are an effective means to alleviate problems that occur in a variety of Chinese lily during replanting, but little is known about the changes in microbial structure during this process. In the present study, we applied four treatments: CK (control), SF (silicon fertilizer), MF (microbial agents), and SMF (combination of silicon fertilizer and microbial agents). We treated the soil constantly for three years and investigated the bacterial community structure and some specific microbial groups in the soil of the lily root zone using 16S rRNA high-throughput sequencing analysis. The results showed that silicon fertilizer and microbial agent treatment significantly improved the growth status of the plants and changed the diversity and structure of the bacterial community in the soil. The genus Pseudomonas significantly increased in the SF treatment, and the phylum Actinobacteria and the genera Nordella, Devosia, and Rhodoplanes significantly increased in the SMF treatment. The genera Nordella, Pedomicrobium, and Chthoniobacter correlated with the seedling index or available silicon content. In addition, the two genera Gaiella and Nocardioides were the key species linking the bacterial community in the soil. The soil physicochemical properties played an important role in restoring the soil bacterial community structures. In conclusion, silicon fertilizer and microbial agents changed the diversity and structure of the bacterial community. Under the fertilizer supplement model, the enrichment of the phylum Actinobacteria and the genus Pseudomonas played an important role in improving soil health and alleviating CRPs in lilies. In addition, organic matter, available phosphorus, available potassium, and available silicon were found to be the most important factors that have a great impact on the restoration of bacterial community structures. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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13 pages, 2348 KiB

Open AccessArticle

Consortia of Plant-Growth-Promoting Rhizobacteria Isolated from Halophytes Improve the Response of Swiss Chard to Soil Salinization

by Susana Redondo-Gómez, Elena Romano-Rodríguez, Jennifer Mesa-Marín, Cristina Sola-Elías and Enrique Mateos-Naranjo

Agronomy 2022, 12(2), 468; https://doi.org/10.3390/agronomy12020468 - 13 Feb 2022

Cited by 16 | Viewed by 3530

Abstract

Inadequate fertilization or the indiscriminate use of water with high salt concentrations have led to salinization of agricultural soils. In this context, biofertilization with plant-growth-promoting rhizobacteria (PGPR) is an environmentally benign strategy to stimulate plant growth, even under salt stress. Thus, we studied [...] Read more.

Inadequate fertilization or the indiscriminate use of water with high salt concentrations have led to salinization of agricultural soils. In this context, biofertilization with plant-growth-promoting rhizobacteria (PGPR) is an environmentally benign strategy to stimulate plant growth, even under salt stress. Thus, we studied the use of isolated PGPR consortia from halophytes to enhance Swiss chard growth under saline conditions. Growth, photosynthetic apparatus response, nutrient status, pigment concentrations, and secondary metabolites with antioxidant activity were determined in Swiss chard plants grown at 0 and 85 mmol L⁻¹ NaCl. In general, inoculation of plants with PGPR has been shown to be an effective strategy to stimulate the growth of Swiss chard and improve its tolerance to salt stress. Inoculated plants watered with 85 mmol L⁻¹ NaCl showed higher values of leaf dry weight than control plants. Furthermore, PGPR inoculation reduced electrolyte leakage and Na⁺ uptake and improved chlorophyll a fluorescence parameters, chlorophyll and carotenoid concentrations, stomatal conductance, and antioxidant capacity of Swiss chard. Finally, our findings highlight the potential of isolated PGPR from halophytes to counterbalance the deleterious effect of salinity and stimulate crop growth. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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19 pages, 2902 KiB

Open AccessArticle

Assessing the Biofortification of Wheat Plants by Combining a Plant Growth-Promoting Rhizobacterium (PGPR) and Polymeric Fe-Nanoparticles: Allies or Enemies?

by Manuel Merinero, Ana Alcudia, Belén Begines, Guillermo Martínez, María Jesús Martín-Valero, Jesús Alberto Pérez-Romero, Enrique Mateos-Naranjo, Susana Redondo-Gómez, Salvadora Navarro-Torre, Yadir Torres, Francisco Merchán, Ignacio D. Rodríguez-Llorente and Eloísa Pajuelo

Agronomy 2022, 12(1), 228; https://doi.org/10.3390/agronomy12010228 - 17 Jan 2022

Cited by 17 | Viewed by 4600

Abstract

Biofortification has been widely used to increase mineral nutrients in staple foods, such as wheat (Triticum aestivum). In this study, a new approach has been used by analyzing the effect of inoculation with a plant growth-promoting rhizobacterium (PGPR), namely, Bacillus aryabhattai [...] Read more.

Biofortification has been widely used to increase mineral nutrients in staple foods, such as wheat (Triticum aestivum). In this study, a new approach has been used by analyzing the effect of inoculation with a plant growth-promoting rhizobacterium (PGPR), namely, Bacillus aryabhattai RSO25 and the addition of 1% (v/v) of organometallic Fe-containing polymeric nanoparticles (FeNPs) alone and in combination. Previously, the minimal inhibitory concentration of FeNPs for the bacterium was determined in order not to inhibit bacterial growth. All treatments had minor effects on seed germination and plant survival. Considering the physiology of plants, several photosynthetic parameters were significantly improved in individual treatments with FeNPs or the bacterium, particularly the efficiency of the photosystem II and the electron transport rate, which is indicative of a better photosynthetic performance. However, at the end of the experiment, a significant effect on final plant growth was not observed in shoots or in roots. When using FeNPs alone, earlier spike outgrow was observed and the final number of spikes increased by 20%. Concerning biofortification, FeNPs increased the concentration of Fe in spikes by 35%. In fact, the total amount of Fe per plant base rose to 215% with regard to the control. Besides, several side effects, such as increased Ca and decreased Na and Zn in spikes, were observed. Furthermore, the treatment with only bacteria decreased Na and Fe accumulation in grains, indicating its inconvenience. On its side, the combined treatment led to intermediate Fe accumulation in spikes, since an antagonist effect between RSO25 and FeNPs was observed. For this reason, the combined treatment was discouraged. In conclusion, of the three treatments tested, FeNPs alone is recommended for achieving efficient Fe biofortification in wheat. Full article

(This article belongs to the Special Issue How Could Microorganisms Benefit the Agriculture Environment?)

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