Plant Root Biomass Research Articles

Determination of optimal gamma radiation dose for mutation breeding in 'Sabz' fig (Ficus carica L.) cuttings based on radiosensitivity and phenotypic changes.

The dried fig cv. Sabz of Iran, distinguishes out among the several fig cultivars for its unique characteristics and excellent properties. The aims to this study were 1) Carefully monitoring the resulting phenotypic changes in growth patterns, leaf morphology, shoot traits, root characteristics, and other relevant traits after irradiated with different gamma rays; 2) Investigating the LD25, 50, 75 and GR25, 50, 75 values at different gamma radiation doses for chose optimum dose. According to our results, the LD50 was 70 Gy, while the LD25 and LD75 were approximately 48 and 95 Gy, respectively. Data analysis revealed that higher doses, ranging from 50 to 90 Gy, led to a reduction in leaf area for fig hardwood cuttings compared to those exposed to lower doses of gamma irradiation (10, 20, 30, and 40 Gy). In fig cuttings, the plant height gradually decreased in line with increasing irradiation doses up to 60 Gy. Among the root traits, root number was particularly influenced by higher radiation doses. On other hand, when fig cuttings were exposed to a 40 Gy radiation dosage, the average root count dropped by 50%. However, when fig cuttings were subjected to a 90 Gy radiation dose, the average root count surged by 90.7% in comparison to the control treatment. Additionally, the GR50 values were 63 Gy for internode length, 67 Gy for leaf area and 56 Gy for plant height and aerial biomass. However, the GR50 values for root number, root volume, and root biomass were 46 Gy, 57 Gy, and 51 Gy, respectively. An analysis based on the GR25, GR50, and GR75 values indicated that plant height, aerial biomass and root biomass exhibited greater sensitivity to radioactivity in comparison to other plant portions of the fig. According to the biological responses in the 'Sabz' fig, 60 Gy of gamma radiation is a suitable dose for initial mutagenesis studies.

Exogenous Oxygen Replenished as a Promising Method for Mitigating Salt Stress in Maize Seedling Stage

ABSTRACT Soil salinization is one of the main reasons for soil degradation, which limiting the improvement of soil productivity. To evaluate the response plant height, stem diameter, plant biomass and nutrient uptake of maize, and soil properties to various salt stress and oxygen supply rates, a soil culture experiment with two factors were carried out: different salt stress degrees (A0, 0 g L−1 NaCl irrigation; A3, 3 g L−1 NaCl irrigation; A6, 6 g L−1 NaCl irrigation; A9, 9 g L−1 NaCl irrigation;) and different rhizosphere oxygen supply degrees (B0, 0 ml L−1 H2O2 solution; B0.5, 0.5 ml L−1 H2O2 solution; B1, 1 ml L−1 H2O2 solution; B1.5, 1.5 ml L−1 H2O2 solution). The results showed that the plant height, stem diameter, aboveground and root biomass of maize under different salt stress degrees were reduced by 6.8–9.8%, 4.4–9.8%, 18.4–45.5% and 21.4–35.8% at the end of the experiment compared to A0, respectively. Meanwhile, the nutrient uptake of aboveground and root were declined, especially under high salt stress degree, but the sodium (Na+) uptake was increased significantly. Rhizosphere oxygen supply enhanced the plant height, stem diameter, aboveground and root biomass by 2.0–6.5%, 4.1–6.1%, 27.5–56.6% and 19.5–47.1% at the end of the experiment compared to B0, respectively. The restriction of nutrient absorption caused by salt stress could be alleviated. Soil quality indicators were influenced by salt stress and oxygen supply management as well. Overall, rhizosphere oxygen supply could alleviate the restriction of salinization on maize growth at seedling stage, improve soil chemical quality and water use efficiency.

Evaluation of Plant Growth-Promoting Rhizobacteria on chilli (<em>Capsicum annuum</em> L.) and brinjal (<em>Solanum melongena</em> L.) growth

This study investigates the potential of Plant Growth-Promoting Rhizobacteria (PGPR) strains, isolated from the rhizosphere of Oroxylum indicum, to enhance the growth of chilli (Capsicum annuum L.) and brinjal (Solanum melongena L.). With the increasing global demand for sustainable agricultural practices, PGPR offers an eco-friendly alternative to chemical fertilizers and pesticides. The research involved screening ten PGPR strains and their consortia for compatibility, followed by evaluating their effects on plant growth parameters, including plant height, shoot biomass, and root biomass, under controlled conditions. Statistical analysis indicated that both individual and consortia PGPR treatments significantly improved growth performance compared to untreated controls. Results demonstrated that three individual strains (Btr-7, Bcer-24, and Bcer-25) significantly enhanced plant height and biomass in chilli plants. For brinjal plants, the strains Erog-1 and Bcer-21 showed significant growth improvements when applied individually. Additionally, the use of PGPR consortia, specifically Btro-7+Bcer-13, Ptai-40+Sarl-43, Bthu-4+Bcer-24, and Bcer-24+Bcer-25, led to substantial increases in plant height and biomass for both chilli and brinjal plants. These findings highlight the potential of PGPR, both as individual strains and in consortia, to promote sustainable crop production, reducing the reliance on chemical fertilizers. Future research should focus on field trials to validate these results under diverse agro-climatic conditions and explore the commercialization potential of effective PGPR strains.

Bacillus endophytes for sustainable management of tomato spotted wilt virus and yield production.

Tomato-spotted wilt virus (TSWV) from the Tospovirus genus affects over 1000 plant species, including key crops, and traditional control methods often prove inadequate. This study investigates the effectiveness of Bacillus amyloliquefaciens and Bacillus subtilis in reducing TSWV infection, enhancing plant growth, and strengthening defense in Nicotiana benthamiana. The aim is to assess Bacillus as a sustainable biocontrol alternative, offering an eco-friendly solution for managing TSWV disease in agriculture. Here, we report the efficacy of five Bacillus isolates (out of 15 tested) - B. amyloliquefaciens (DJB5, YN48, YN28, Mg6) and B. subtilis L1-21 - significantly reducing TSWV copies per gram in N. benthamiana leaves, using a half-leaf assay. In glasshouse trials, isolates DJB5, YN48, and Mg6 decreased TSWV copies per gram by 75.7%, 83.6%, and 88.2%, with biocontrol efficacy rates of 91.2%, 94.1%, and 95.7% respectively. All the isolates consistently mitigated the symptoms of TSWV, reduced the disease severity, and area under the disease progress curve (AUDPC) at 21 days post-inoculation. Additionally, these isolates enhanced plant growth parameters, including shoot and root length, leaf number, area, and biomass. The application of endophytes in the infected plants activated antioxidant defense enzymes by elevating the activities of polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), and chitinase. However, defense-related enzymes, such as malondialdehyde (MDA), catalase (CAT), phenylalanine ammonia-lyase (PAL), total phenol, and β-1,3-glucanase decreased as TSWV infection reduced in the leaves. Our findings indicate that B. amyloliquefaciens isolates, DJB5, YN48, and Mg6, effectively manage TSWV by activating plant defense, reducing virus load, reducing TSWV symptoms, and promoting plant growth. © 2024 Society of Chemical Industry.

Growth and physiological response of Yulu Hippophae rhamnoides to drought stress and its omics analysis

ABSTRACT Hippophae rhamnoides (H. rhamnoides) is the primary tree species known for its ecological and economic benefits in arid and semi-arid regions. Understanding the response of H. rhamnoides roots to drought stress is essential for promoting the development of varieties. One-year-old Yulu H. rhamnoides was utilized as the experimental material, and three water gradients were established: control (CK), moderate (T1) and severe (T2), over a period of 120 days. The phenotypic traits and physiological indies were assessed and analyzed, while the roots were subjected by RNA-Seq transcriptome and Tandem Mass Tags (TMT) proteome analysis. Drought stress significantly reduced the plant height, ground diameter, root biomass and superoxide dismutase activity; however, the main root length increased. In comparison with CK, a total of 5789 and 5594 differential genes, as well as 63 and 1012 differential proteins, were identified in T1 and T2, respectively. The combined analysis of transcriptome and proteome showed that the number of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) associated with T1, T2 and CK was 28 and 126, respectively, with 7 and 36 genes achieving effective KEGG annotation. In T1 and T2, the differential genes were significantly enriched in the plant hormone signal transduction pathway, but there was no significant enrichment in the protein expression profile. In T2, 38 plant hormone signal transduction function genes and 10 peroxisome related genes were identified. With the increase of drought stress, the combined expression of DEGs and DEPs increased. Yulu H. rhamnoides may allocate more resources toward CAT while simultaneously decreasing SOD and POD to mitigate the oxidative stress induced by drought. Furthermore, the molecular mechanisms underlying plant hormone signal transduction and peroxisome-related genes in the roots of H. rhamnoides were discussed in greater detail.

Phytotoxicity of Prussian blue nanoparticles to rice and the related defence mechanisms: In vivo observations and physiological and biochemical analysis

While the nanotoxic effects on plants have been extensively studied, the underlying mechanisms of plant defense responses and resistance to nanostress remain insufficiently understood. Particularly, Prussian blue nanoparticles (PB NPs) have been extensively used in pigments, pharmaceuticals, electrocatalysis, biosensors and energy storage. However, the impact of PB NPs on plants’ health and growth are largely unknown. Herein, the phytotoxicity of PB NPs to rice and trace the uptake, accumulation and biotransformation of PB NPs was explored, along with the underlying defence mechanisms. The results showed that PB NPs (≥ 50 mg L–1) significantly inhibited the growth of rice seedling up to 16.16%, 27.80%, and 29.37% in plant height, shoot biomass and root biomass, respectively. The X-ray spectroscopic studies and in vivo elemental and particle-imaging demonstrated that PB NPs were transported through the cortex via xylem from root to shoot. However, most of the PB NPs and their transformation products were retained in the root, where they were blocked owing to root cell wall (RCW) remodelling, and 81.4%-83.4% of Fe accumulated in the RCW compared to 66.6% in the control. Specifically, PB NPs stimulated pectin methylesterase activity by promoting hydrogen peroxide production to participate in RCW remodeling. More interestingly, Si was specifically regulated to covalently bind to hemicellulose to form the Si-hemicellulose complex that strongly bound with PB NPs during RCW remodeling, resulting in the strong defense against PB NPs. These findings provide new insights into the phytotoxicity of artificial NPs and the defense mechanisms of plants.

Characterization of Sulfur Oxidizing Bacteria and Their Effect on Growth Promotion of Brassica napus L.

Oil seeds sector is one of the major dynamic components of the agriculture world. Oil seeds such as canola (Brassica napus) require a higher quantity of sulfur (S), which is supplied through inorganic fertilizers. However, the overapplication of agro-chemicals to get higher yields of crops is harming the soil health. Therefore, the application of bacterial cultures with plant growth-promoting activity as biofertilizers ensures soil health maintenance and enhances crop productivity. To achieve this aim, the present research was initiated by procuring three sulfur-oxidizing bacteria (SOBs), namely, SOB 5, SOB 10, and SOB 38, from the Microbiology Department, PAU. In the initial assessment, all three SOB cultures showed resilience to pesticide toxicity at the recommended dosage, with the exception of ridomil. These cultures were later characterized morphologically, biochemically, and at the molecular level using 16s rRNA resulting in their identification as Enterobacter ludwigii strain Remi_9 (SOB 5), Enterobacter hormaechei strain AUH-ENM30 (SOB 10), and Bacillus sp. 5BM21Y12 (SOB 38). Functional characterization of these SOB cultures revealed their ability to exhibit multifarious plant growth-promoting traits. Bacillus sp. 5BM21Y12 showed greater functional activity, including high P solubilization (14.903 µg/mL), IAA production (44.28 µg/mL), siderophore production (13.89 µg/mL), sulfate ion production (0.127 mM), ammonia excretion (2.369 µg/mL), and Zn solubilization (22.62 mm). Based on the results of functional and molecular characterization, Bacillus sp. 5BM21Y12 was selected for field trials by formulating different treatments. Composite treatment, T8 (100% S + Bacillus sp. + pesticides) significantly enhanced growth parameters (plant height, root, and shoot biomass), yield attributes (siliqua length, test weight, number of siliqua/plant), yield parameter (total biomass and seed yield), quality parameter (crude protein and oil) as compared to all other sole treatments employed in the field. A combined application of non-pathogenic Bacillus sp. 5BM21Y12, with good functional activity enhanced yield of crop due to synergistic and additive interaction with fertilizer/pesticides. As biofertilizer application reduces the input of pesticides/fertilizers new inoculant formulations with cell protectors and the development of compatible pesticides should be searched to assure the benefits of integrated treatment.

The roles of nanoparticle-enriched biochars in improving soil enzyme activities and nutrient uptake by basil plants under arsenic toxicity

Enriched biochar with improved properties and functionality can play a significant role in providing sustainable solutions for mitigating heavy metal contamination in soil. In this experiment, the effects of solid and enriched biochars (potassium-enriched biochar (BC-K), magnesium-enriched biochar (BC-Mg), both individually and combined) were examined on soil microbial and enzyme activities, as well as nutrient uptake by basil plants cultivated in a soil with three levels of arsenic (nontoxic, 50 mg As kg−1 soil, and 100 mg As kg−1 soil). Biochar-related treatments, increased soil organic matter (65–76%), while decreased availability of arsenic (6–55%) in the soil. The microbial biomass carbon (by about 123%) and soil basal respiration (by about 256%), and soil enzymatic activities (β-glucosidase, urease, alkaline phosphatase, and dehydrogenase) were enhanced by enriched biochars under arsenic toxicity. The solid and particularly enriched biochars decreased arsenic content and improved nitrogen and phosphorus contents of roots and shoots, root length, root activity, and root and shoot biomass in basil plants. Therefore, it is conceivable to suggest that enriched biochars are superior treatments for improving nutrient absorption rates and basil growth under arsenic toxicity through decreasing arsenic mobility and increasing soil microbial activities.

Elucidation of biochemical and physiological modulations in Triticum aestivum induced by green synthesized nitrogen-enriched zinc nano-complexes

This study investigates the efficacy of a green synthesized nitrogen-rich zinc complex (Zn-NC) using quinoline (C9H7N) as the nitrogen-rich substrate to enhance growth and biochemical properties in wheat (Triticum aestivum). The performance of Zn-NC was compared to standard zinc oxide nanoparticles (ZnO-NPs). Both Zn-NC and ZnO-NPs were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and dynamic light scattering (DLS). Three concentrations (100, 200, and 500 ppm) of each compound, along with a control, were applied to local soil samples (n=3). The physiological (biomass, elongation) and biochemical effects (chlorophyll, carotenoids, flavonoids, and phenols) on wheat were investigated. Potential phytotoxic effects were evaluated to establish the biostimulants' safety thresholds. Plants treated with green Zn-NC showed an average increase in shoot length of 25 % compared to the control group. The chlorophyll content in plants treated with ZnO-NPs increased by 18 %, while those treated with green Zn-NC increased by 12 % compared to control. Application of ZnO-NPs resulted in a 30 % increase in total yield, whereas green Zn-NC treatment led to a 22 % yield increase. The root biomass of plants treated with ZnO-NPs increased by 28 %, and those treated with green Zn-NC saw a 20 % increase compared to controls. Based on the optimization of overall results, the ZnO NPs showed phytotoxic effects at concentrations above 200 ppm, while green Zn-NC exhibited no significant phytotoxicity even at concentrations up to 300 ppm. This study delineates the optimal concentrations of Zn-NC and ZnO-NPs that can enhance nutrient delivery and yield in cereal crops while mitigating phytotoxic risks. The findings provide valuable insights into applying nano-biostimulants in agroecosystems, highlighting their potential to improve productivity and sustainability in agriculture.

Salicylic acid functionalized chitosan nanocomposite increases bioactive components and insect resistance of Agastache rugosa

The abundance of monoterpenoids and phenolic compounds determines the medicinal quality and anti-insect properties of Agastache rugosa, which can be compromised by biotic stress such as herbivore attacks. The traditional use of chemical pesticides to mitigate herbivore interference is increasingly incompatible with sustainable agriculture. In response, nanotechnology-based biostimulants, which can activate metabolic processes to enhance plant growth and stress resistance, offer a more cost-effective and environmentally-friendly alternative. However, to date, it remains unknown how nano-biostimulants improve the therapeutic value and insect resistance of medicinal plants simultaneously. This study investigates the effect of 0–1000 mg/L of a nano-biostimulant salicylic acid functionalized chitosan nanocomposite (SCN) on the pharmacological and anti-herbivore properties of medicinal plant A. rugosa. Results showed that 100 mg/L SCN significantly inhibited Spodoptera litura growth by 62.9 %, and increased plant shoot and root biomass by 107.2 % and 77.6 %, respectively. Moreover, 100 mg/L SCN significantly upregulated the expression of the key genes (e.g., LS, L3OH, and CHS) involved in monoterpene and phenolic compounds biosynthesis by 1.4–10.1 folds, thus boosting the production of active compounds such as pulegone, β-myrcene, and chlorogenic acid by 1.5–24.4 folds. These enhancements were superior to salicylic acid or chitosan alone. Altogether, our findings promote the sustainable and eco-friendly application of nano-biostimulant in improving the quality of medicinal plants and green pest control in agroecosystems.

Effects of microplastics concentration on plant root traits and biomass: Experiment and meta-analysis

The impact of microplastics (MPs) on plant growth, particularly root development, remains underexplored. To address this, a laboratory pot experiment and meta-analysis were conducted to assess how varying concentrations of MPs affect plant root growth. In pot experiments, the response of root traits to MPs differed by plant species. For F. arundinacea, a higher addition (1 % and 2 %) of polypropylene (PP) significantly increased the total length, surface area, volume, as well as fine root (<1 mm) surface area and volume. Partial least squares path modeling (PLS-PM) analysis showed that high concentrations of MPs affected plant root growth and plant root biomass by promoting fine root growth. Meta-analysis indicated that MPs increased shoot dry biomass by 32.7 % but reduced root dry biomass by 4.1 % and root length by 14.3 %. Higher concentrations (>0.5 %) of MPs significantly increased root length (35.2 %) and root dry biomass (6.3 %), whereas decreased shoot dry biomass (-8.6 %). Under the lower MPs concentration (<0.5 %), the root length and root dry biomass were decreased by 18.6 % and 11.1 %, respectively, and the shoot dry biomass was increased by 53.2 % compared with the treatment without MPs. The results emphasize the differences in performance between species for different MPs concentrations, implying that there may be future scope to select for species/varieties that are most resilient to the presence of MPs.

Spent coffee waste-derived biochar improves physical properties, water retention, and maize (Zea mays L.) growth in sandy soil

Adding organic soil amendments can improve the physical and hydrological properties of soil, subsequently enhancing fertility for better crop production. In this study, spent Arabica and Columbian coffee wastes and their respective biochars were evaluated as soil amendments to improve the physical and hydrological properties of loamy sand soil and enhance maize (Zea mays L.) crop growth. Spent Arabica coffee (AC) and Columbian coffee (CC) wastes were collected and transformed into biochar through pyrolysis process at 550 °C with a residence time of 3 h and pyrolysis rate of 5 °C per minute. The AC and CC derived biochar were termed as ABC and CBC, respectively. The produced soil amendments were applied to soil at 0% (control), 1%, 3%, and 5% in a column setup. The moisture characteristics, including water infiltration, evaporation, and water retention, were investigated. Thereafter, the prepared amendments were applied to loamy sand soils at 0% (control), 1%, 3%, and 5% (w/w) application rates. Maize growth was then observed for a period of 30 days under greenhouse conditions. Results of the column trials showed that ABC and CBC applied at 5% reduced the cumulative water evaporation by 57%–66% and cumulative infiltration by 124%–181% compared to control. Likewise, 5% application of ABC and CBC resulted in 101 to 130% higher water retention in loamy sand soil. Results of the greenhouse experiment showed that 5% application of ABC and CBC amendments resulted in root biomass of 2.12 and 2.38 g, respectively, as compared to 0.51 g in control treatment. Similar treatments resulted in shoot biomass of 9.70 and 9.93 g respectively, as compared to 7.37 g in control. Likewise, 5% application of CBC and ABC increase plant height from 15.71 to 30.94 cm in ABC and 33.23 cm in CBC. Overall, 5% application of coffee waste-derived biochars significantly reduced water evaporation and infiltration, while increasing soil water retention and maize plant height, root biomass, and shoot biomass. Therefore, spent coffee waste-derived biochar could effectively be employed to improve physical and hydrological properties of loamy sand soils for better crop productivity.

Enhancing drought resistance in Pinus tabuliformis seedlings through root symbiotic fungi inoculation.

Drought constitutes a major abiotic stress factor adversely affecting plant growth and productivity. Plant-microbe symbiotic associations have evolved regulatory mechanisms to adapt to environmental stress conditions. However, the interactive effects of different fungi on host growth and stress tolerance under drought conditions remain unclear. This study explored the effects of varying polyethylene glycol (PEG-6000) concentrations (0%, 15%, 25%, and 35%) on the growth and physiological responses of two ectomycorrhizal fungi (Suillus granulatus (Sg) and Pisolithus tinctorius (Pt)) and two dark septate endophytes (Pleotrichocladium opacum (Po) and Pseudopyrenochaeta sp. (Ps)) isolated from the root system of Pinus tabuliformis. Specifically, the study aimed to evaluate six inoculation treatments, including no inoculation (CK), single inoculations with Sg, Pt, Po, Ps, and a mixed inoculation (Sg: Pt : Po: Ps = 1:1:1:1), on the growth and physiological characteristics of P. tabuliformis seedlings under different water regimes: well-watered at 70% ± 5%, light drought at 50% ± 5%, and severe drought at 30% ± 5% of the maximum field water holding capacity. All four fungi exhibited the capacity to cope with drought stress by enhancing antioxidant activities and regulating osmotic balance. Upon successful root colonization, they increased plant height, shoot biomass, root biomass, total biomass, and mycorrhizal growth response in P. tabuliformis seedlings. Under drought stress conditions, fungal inoculation improved seedling drought resistance by increasing superoxide dismutase and catalase activities, free proline and soluble protein contents, and promoting nitrogen and phosphorus uptake. Notably, mixed inoculation treatments significantly enhanced antioxidant capacity, osmotic adjustment, and nutrient acquisition abilities, leading to superior growth promotion effects under drought stress compared to single inoculation treatments. All four fungi tolerated PEG-induced drought stress, with increased antioxidant enzyme activities and osmotic adjustment substances and they promoted the growth and enhanced drought resistance of P. tabuliformis seedlings.

Assessing the Early Establishment and Adaptability of Italian Ryegrass (Lolium multiflorum) in Irrigated and Rainfed Conditions of Punjab, Pakistan

In Punjab, Pakistan, more than 60% expenditure incurred on the feeding of livestock and offered low quality forage thus affecting the productivity of milk and meat. The less production of livestock oriented products often results malnutrition in the society. An effort was made to evaluate the Italian Ryegrass (Lolium multiflorum) early growth and its adaptation to rainfed and irrigated environments. The main objective of this study is to provide important new information for sustainable fodder production systems. The experiment used a Randomized Complete Block Design with seeds obtained from Korea and was carried out in the winter of 2023 in both rainfed Chakwal and irrigated Sargodha zone of Punjab. The plant's response to varying soil conditions and water availability was evaluated by measuring a range of growth parameters, such as plant height, population density, root and shoot biomass, root length, and the root-shoot ratio. The results show that there are significant differences between rainfed and irrigated locations as established by the statistical analysis. Italian Ryegrass in irrigated plots showed higher mean plant height (43.75 cm), higher plant population (317.50 plants/m²), higher shoot biomass (7.425 g/plant), greater length of roots (5.950 cm), and a lower root-shoot ratio (0.1135) than in rainfed areas. Additionally, the study provides data on soil profiles that show differences between the two locations in terms of pH, electrical conductivity, nitrogen, phosphorus, and potassium. The findings provide important information for enhancing Italian Ryegrass cultivation in Punjab's various agro-ecological zones, given the critical role fodder feed plays in supporting livestock and agriculture. The study provides the basis for well-informed farming practices by highlighting the importance of water management strategies to improve fodder production during scarcity period and, by consequently, animal nutrition in the area.

Cadmium exposure on physiological responses of Erythrophleum fordii seedlings: A comparative study

The adaptability and tolerance of native species to heavy metal-contaminated soils can provide crucial insights for the development of effective heavy metal remediation strategies. Erythrophleum fordii (E. fordii) is a native hardwood species endemic to southern China that exhibits nitrogen fixation and soil improvement capabilities. This study examined the growth and physiological responses of E. fordii seedlings to varying cadmium (Cd) concentrations (control, Cd50, Cd100, Cd150, corresponding to 0, 50, 100, and 150 ppm), aimed to ascertain its potential role in phytoremediation efforts. Current results demonstrated that a moderate concentration of Cd (Cd50) significantly enhanced several plant characteristics, including plant height, root biomass, stem biomass, net photosynthetic rate, maximum net photosynthetic rate, and light saturation point. These observed improvements ranged from 12.15 % to 32.88 %, compared with control. Conversely, the highest Cd level (Cd150) resulted in substantial reductions in plant height, root biomass, chlorophyll content, and gas exchange parameters. Furthermore, malondialdehyde content increased markedly at Cd100 and Cd150 levels by 68.86 % and 118.92 %, respectively. The activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the content of osmotic regulatory substances (soluble protein and soluble sugar) reached their peaks at Cd100 level, increased by 32.61–88.39 %. This indicated E. fordii's capacity to mitigate Cd-induced stress. Significant correlations were observed between growth indicators, chlorophyll content, and net photosynthetic rate, as well as between antioxidant enzymes and osmotic substances. The principal component analysis highlighted the superior performance of E. fordii in Cd50 treatment. The results revealed that moderate Cd promoted growth, photosynthetic activity, and physiological resilience in E. fordii, whereas the highest concentration of Cd (Cd150) was detrimental. These findings offer perceptiveness to the cultivation of E. fordii and its tolerance to heavy metals, with implications for the remediation of Cd-contaminated soils.

Structured water uses in improving rhizosphere microbiota and growth of Cleistocactus strausii

Research objective: The paper presents the results of research aiming plant growth and to stimulate microbial communities in rhizosphere of Cleistocactus strausii which was watered with structured water under controlled conditions. Materials and Methods: The experiments, which began in January 2023, were conducted in the CREA-OF greenhouses in Pescia (PT), Tuscany, Italy (43°54′N 10°41′E) on Cleistocactus strausii. The plants were placed in ø12 cm pots; 30 plants per thesis, divided into 3 replicates of 10 plants each. The experimental groups were: i) group without structured water, irrigated with water and previously fertilised substrate; ii) group with structured water, previously fertilised substrate. On 20 January 2024, plant height, stem circumference, vegetative weight, root weight, root lenght, number of new suckers, microbial count in the plants (evaluation of the type of bacteria and fungi in the substrate) were measured. Results and Discussion: The experiment showed that the use of structured water can improve the vegetative and root growth of Cleistocactus strausii plants grown in pots. The treatment also resulted in an increase in plant height, stem circumference, root hair length and number of new suckers. The trial also highlighted how the use of structured water in plant growing media can increase bacterial and fungal biodiversity in terms of number and taxonomic diversity. In fact, the substrates of the treated plants showed the presence of 5 different bacterial and fungal taxa compared to the control. The presence of fewer plants affected by biotic phytopathologies is evident in the treatment with structured water. Conclusions: Specifically, structured water has been shown to promote the growth of Cleistocactus strausii, according to experimental results. Plant height, vegetative and root biomass were significantly increased. Additionally, the number of useful microorganisms found on the substrate of theses treated with structured water increased, which likely supported plant growth improvement. Plants can also be affected by microorganisms in their substrates if they are exposed to biotic or abiotic stress. These aspects consequently become very interesting for the grower who can reduce the use of water and fertilisers and increase the quality of the plants by using alternative techniques.

Mycorrhizal Symbiosis Enhances P Uptake and Indole-3-Acetic Acid Accumulation to Improve Root Morphology in Different Citrus Genotypes

Arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth via stimulation of root system development. However, the extent of their effects and underlying mechanisms across different citrus genotypes remain to be fully elucidated. This study investigates the impact of Funneliformis mosseae (F. mosseae) inoculation on plant growth performance, root morphology, phosphorus (P), and indole-3-acetic acid (IAA) concentrations, as well as the expression of related synthesis and transporter genes in three citrus genotypes: red tangerine (Citrus tangerine ex. Tanaka), kumquat (Fortunella margarita L. Swingle), and fragrant citrus (Citrus junos Sieb. ex. Tanaka). Following 12 weeks of inoculation, significant improvements were observed in plant height, shoot and root biomass, total root length, average root diameter, second-order lateral root development, root hair density, and root hair length across all genotypes. Additionally, F. mosseae inoculation significantly increased root P and IAA concentrations in the three citrus genotypes. Notably, phosphatase activity was enhanced in F. margarita but reduced in C. tangerine and C. junos following inoculation. Gene expression analysis revealed a universal upregulation of the P transporter gene PT5, whereas expressions of the auxin synthesis gene YUC2, transporter gene LAX2, and phosphatase gene PAP1 were commonly downregulated. Specific to genotypes, expressions of YUC5, LAX5, PIN2, PIN3, PIN6, and expansin genes EXPA2 and EXPA4 were significantly upregulated in C. tangerine but downregulated in F. margarita and C. junos. Principal component analysis and correlation assessments highlighted a strong positive association between P concentration, P and auxin synthesis, and transporter gene expressions with most root morphology traits, except for root average diameter. Conversely, IAA content and phosphatase activities were negatively correlated with these root traits. These findings suggest that F. mosseae colonization notably enhances plant growth and root system architecture in citrus genotypes via modifications in P transport and IAA accumulation, indicating a complex interplay between mycorrhizal symbiosis and host plant physiology.

Insect root feeders incur negative density-dependent damage across plant species in an alpine meadow.

Although herbivores are well known to incur positive density-dependent damage and mortality, thereby likely shaping plant community assembly, the response of belowground root feeders to changes in plant density has seldom been addressed. Locally rare plant species (with lower plant biomass per area) are often smaller with shallower roots than common species (with higher plant biomass per area) in competition-intensive grasslands. Likewise, root feeders are often distributed in the upper soil layers. We hypothesized, therefore, that root feeders would incur negative density (biomass)-dependent damage across plant species. To test this hypothesis, we investigated the diversity and abundance of plant and root feeder species in an alpine meadow and determined the diet of the root feeders using metabarcoding. Across all species, root feeder load decreased with increasing aboveground plant biomass, root biomass, and total plant biomass per area, indicating a negative density dependence of damage across plant species. Aboveground plant biomass per area increased with increasing individual plant biomass and root depth per area across species, suggesting that rare plant species were smaller in size and had shallower root systems compared to common plant species. Both root biomass per area and root feeder biomass per area decreased with soil depth, but the root feeder biomass decreased disproportionately faster compared to root biomass with increasing root depth. Root feeder load decreased with increasing root depth but was not correlated with the feeding preference of root feeder species. Moreover, the prediction derived from a random process incorporating vertical distributions of root biomass and root feeder biomass significantly accounted for interspecific variation in root feeder load. In conclusion, the data indicate that root feeders incur negative density-dependent damage across plant species. On this basis, we suggest that manipulative experiments should be conducted to determine the effect of the negative density-dependent damage on plant community structure and that different types of plant-animal interactions should be concurrently examined to fully understand the effect of plant density on overall herbivore damage across plant species.

Acid rain reduced soil carbon emissions and increased the temperature sensitivity of soil respiration: A comprehensive meta-analysis

Soil respiration the second-largest carbon flux in terrestrial ecosystems, has been extensively studied across a wide range of biomes. Surprisingly, no consensus exist on how acid rain (AR) impacts the spatiotemporal pattern of soil respiration. Therefore, we conducted a meta-analysis using 318 soil respiration and 263 soil respiration temperature sensitivity (Q10) data points obtained from 48 studies to assess the impact of AR on soil respiration components and their Q10. The results showed that AR reduced soil total respiration (Rt) and soil autotrophic respiration (Ra) by 7.41 % and 20.75 %, respectively. As the H+ input increased, the response rates of Ra to AR (RR-Ra) and soil heterotrophic respiration (Rh) to AR (RR-Rh) decreased and increased, respectively. With increased AR duration, the RR-Ra increased, whereas the RR-Rh did not change. AR increased the Q10 of Rt (Rt-Q10) and Rh (Rh-Q10) by 1.92 % and 9.47 %, respectively, and decreased the Q10 of Ra (Ra-Q10) by 2.77 %. Increased mean annual temperature, mean annual precipitation, and initial soil organic carbon increased the response rate of Ra-Q10 to AR (RR-Ra-Q10) and decreased the response rate of Rh-Q10 to AR (RR-Rh-Q10). However, as the AR frequency and initial soil pH increased, both RR-Ra-Q10 and RR-Rh-Q10 also increased. In summary, AR decreased Rt but increased Q10, likely due to soil acidification (soil pH decreased by 7.84 %), reducing plant root biomass (decreased by 5.67 %) and soil microbial biomass (decreased by 5.67 %), changing microbial communities (increased fungi to bacteria ratio of 15.91 %), and regulated by climate, vegetation, soil and AR regimes. To the best of our knowledge, this is the first study to reveal the large-scale, varied response patterns of soil respiration components and their Q10 to AR. It highlights the importance of applying the reductionism theory in soil respiration research to enhance our understanding of soil carbon cycling processes with in the context of global climate change.

Soil gravel content and plant species configuration control vegetation restoration in Qinghai‐Tibet Plateau

AbstractSoil gravel content strongly affects ecological restoration; however, the response and mechanism of plant traits to soil gravel content under the sensitive and fragile natural environment of Qinghai‐Tibet Plateau remains unclear. Herein, soils with three gravel content (10%, 30%, 50%) in the southeastern Tibetan Plateau were selected, and three plant species (one native plants of Elymus dahuricus (Ed), and two introduced ones of Festuca elata (Fe) and Medicago sativa (Ms)) were used in seven planting patterns with different proportions (Fe, Ed, Ms, Fe + Ed (1:1), Fe + Ms (2:1), Ed + Ms (2:1), Fe + Ed + Ms (2:2:1)). Plant traits, phytochemical properties and soil stoichiometric characteristics were measured to explore the interactive effects of soil gravels and plant species on vegetation restoration. Average plant height, coverage, shoot biomass, and total biomass were most affected by plant species (F = 277–611, p &lt; 0.01), followed by gravel content (F = 90–195, p &lt; 0.01) and their interaction (F = 5–51, p &lt; 0.05); root biomass was most affected by gravel content (F = 130, p &lt; 0.01). Among plant species, shoot and root biomass, total biomass overall decreased in the order of Fe + Ed + Ms&gt;Fe&gt;Fe + Ms&gt;Fe + Ed&gt;Ms&gt;Ms + Ed&gt;Ed. Plant total biomass, shoot biomass, root biomass and shoot/root ratio among different soils overall decreased in the order of low&gt; high&gt; medium gravel contents. All plant species were restricted by soil nitrogen except for Ed and Ed + Ms (N:P &gt; 14). In addition, increasing the gravel content in the soil will increase the soil bulk density and reduce the total soil porosity. The total soil porosity is significantly positively correlated with the average plant height, coverage, aboveground biomass, and total biomass of plants (r = 0.78–0.91, p &lt; 0.05). The total nitrogen content, total phosphorus (TP) content, and N: P in rhizosphere soil were significantly positively correlated with the average plant height, coverage, aboveground biomass, root biomass, and total biomass of plants (r = 0.70–0.97, p &lt; 0.05), but soil N was significantly positively correlated with aboveground biomass and total biomass (r = 0.69, 0.71, p &lt; 0.05), and there was no significant difference in soil TP content between them. The gravel content directly affects plant growth by changing bulk density and total porosity, but the combined effect of soil nutrients and plants affects plant growth. Therefore, optimizing the configuration of soil properties (mainly nitrogen and compactness) and plant species (isecologic niche plants) is an effective strategy for ecological restoration in the Qinghai‐Tibet Plateau.