Increased Shoot Length Research Articles

Optimization of exogenous CeO2 nanoparticles on Pak choi (Brassica rapa L. var. chinensis) to alleviate arsenic stress

Arsenic (As) is a regulated hazardous substance that persists in the environment, causing issues related to environmental health, agriculture, and food safety. Cerium oxide nanoparticles (CeO2 NPs) are emerging sustainable solutions for alleviating heavy metal stress. However, their effectiveness and optimization for foliar application in reducing As stress, especially in Pak choi, has not been reported yet. Hence, this study aims to examine the effects of foliar application of CeO2 NPs (75,000,000, 150,000,000, and 300,000,000 ng/L) on the growth, nutrient availability, and antioxidant enzymatic activities of Pak choi plants under As stress. The findings showed that foliar application of 75,000,000 ng/L CeO2 NPs significantly increased shoot length (77.32%), root length (80.98%), and number of leaves (80.23%) as compared to control without NPs. The lowest dose of CeO2 NPs (75,000,000 ng/L) increased antioxidant enzyme activities such as peroxidase (86.10%), superoxide dismutase (81.48%), and catalase (52.07%), while significantly reducing malondialdehyde (44.02%), hydrogen peroxide (34.20%), and electrolyte leakage (43.53%). Furthermore, foliar application of 75,000,000 ng/L CeO2 NPs significantly increased the content of zinc (81.02%), copper (56.99%), iron (88.04%), manganese (68.37%), magnesium (76.83%), calcium (61.16%), and potassium (84.91%) in leaves when compared to control without NPs. The same trend was observed for shoot and root nutrient concentrations. Most importantly, 75,000,000 ng/L CeO2 NPs foliar application significantly reduced shoot As (45.11%) and root As (20.89%) concentration compared to control, providing a reassuring indication of their potential to reduce As concentration in plants. Our study’s findings are of utmost importance as they indicate that lower concentrations of foliar-applied CeO2 NPs can be more effective in enhancing crop nutrition and reducing heavy metals than higher concentrations. This article is intended to present critical issues of As contamination in agricultural soils, which imposes substantial risks to crop productivity and food security.

Evaluating the biocontrol efficacy of beneficial soil microbes against the Fusarium wilt disease of tomato

Tomato is one of the most important agricultural crops in the world as it is a rich source of vitamins A and C. The quality and the quantity of tomato fruits is severely affected by the fungal plant pathogens. Fungal diseases are among the most dangerous biological stresses that cause severe damage to tomato crops in many countries. Fusarium wilt disease in tomato caused by Fusarium oxysporum f. sp. lycopersici, become a major concern of yield loss worldwide. This study evaluated the efficacy of multiple antagonistic biocontrol agents, including Trichoderma species and non-pathogenic F. oxysporum, in mitigating Fusarium wilt. Pathogenic F. oxysporum strains were isolated from diseased tomato plants, while biocontrol agents were cultured from rhizosphere soil of healthy tomato plants. In vitro dual-culture assays demonstrated that non-pathogenic F. oxysporum inhibited pathogenic strains by 86.8% (±4.8) at 7 days post-inoculation (dpi), significantly higher than T. harzianum, which achieved 62.8% (±6.2) inhibition (p < 0.01). Other Trichoderma strains, such as T. viride and T. asperellum, showed moderate inhibition levels of 54.3% (±2.3) and 51.9% (±5.9), respectively. Greenhouse pot trials reinforced these in vitro results, with non-pathogenic F. oxysporum achieving a significant disease reduction of 77.0% (±3.0) in Fusarium wilt incidence, followed by T. harzianum at 64.8% (±2.7) (p < 0.01). Statistically significant improvements in plant growth were also recorded in treated plants. T. harzianum increased shoot length by 25.6% (±3.1) and root weight by 22.4% (±2.9) compared to control plants, while non-pathogenic Fusarium enhanced root length by 30.2% (±3.4) and overall biomass by 28.7% (±3.8) (p < 0.01). Data were analyzed using ANOVA, followed by LSD for pairwise comparisons, confirming the efficacy of these biocontrol agents in reducing disease incidence and promoting plant growth. These findings underscore the potential of antagonistic biocontrol agents as viable, sustainable alternatives to chemical fungicides for managing Fusarium wilt in tomato production systems, supporting both plant health and environmental resilience.

Seed priming with ascorbic acid and spermidine regulated auxin biosynthesis to promote root growth of rice under drought stress.

Drought stress severely hampers seedling growth and root architecture, resulting in yield penalties. Seed priming is a promising approach to tolerate drought stress for stand establishment and root development. Here, various seed priming treatments, viz., hydro priming, ascorbic acid priming (AsA), and spermidine priming (Spd), were adopted concerning root morphological, physiological, microstructural, and molecular studies under drought stress on rice variety Hanyou 73. Results demonstrated that drought severely suppressed seedling establishment, while AsA or Spd priming effectively alleviated the inhibitory effects of drought stress, and significantly increased shoot length (24.5-27.9%), root length (34.6-38.8%), shoot dry weight (56.1-97.1%), root dry weight (39.6-40.6%), total root length (47.0-57.8%), surface area (77.0-84.9%), root volume (106.5-109.8%), average diameter (16.4-19.7%), and root tips (46.8-61.1%); meanwhile, priming with AsA or Spd alleviated microscopic and ultrastructural damage from root cell, and improved root activity (183.8-192.0%). The mitigating effects of AsA or Spd priming on drought stress were primarily responsible for decreasing the accumulation of reactive oxygen species by increasing antioxidants activities and osmoprotectants contents, which reduced oxidative stress and osmotic cell potential and facilitated improved water and nutrients absorption in roots. Additionally, seed priming with AsA or Spd substantially improved auxin synthesis by upregulating of OsYUC7, OsYUC11 and, OsCOW1 expression. However, there were certain differences in the defense responses of plants and mechanisms of reducing the damage of drought stress after seed treatment with AsA or Spd. Under stress conditions, AsA had a greater impact on improving the fresh and dry weight of aboveground parts, while Spd affected the concentration of total sugar and total protein in plants. Likewise, the degree of oxidative damage was lowered, and POD and CAT activities were elevated due to Spd priming under water-deficient conditions.

Effects of Rhizobacteria Strains on Plant Growth Promotion in Tomatoes (Solanum lycopersicum).

Numerous factors, such as soil fertility, climatic conditions, human activity, pests, and diseases, limit agricultural yields. Pesticides and fertilizers have become indispensable tools to satisfy the global food demand. However, its adverse environmental effects have led to the search for more sustainable and ethical techniques. Biofertilizers and biopesticides based on plant- growth-promoting rhizobacteria (PGPRs) are efficient and ecological treatments that promote plant growth and protection against pathogens and abiotic stresses. In this study, twelve rhizobacterial strains with plant-growth-promoting attributes were selected to evaluate their plant-growth-promoting effect on tomato plants (Solanum lycopersicum L. var Robin). Soil inoculation with these strains resulted in a significant increase in shoot length, up to 50% when compared with control plants. Regarding fresh biomass, rhizobacterial treatments significantly improved seedlings' fresh aerial weight with a maximum increase of 77%. Root biomass also demonstrated a substantial improvement, yielding 62.26% greater fresh root weight compared to the control. Finally, dry root weights exhibited the most remarkable enhancements, with values between 49 and 124%, when compared to the control plants. Concerning the nutritional status, the strains inoculation increased the macronutrients and micronutrients content in the aerial and root parts of the plants. All these findings suggest that rhizobacteria from different ecosystems and agriculture soils of the Canary Islands could be used as fertilizer inoculants to increase crop yield and promote more sustainable practices in modern agriculture.

Response of transient soil waterlogging on shoot growth pattern and root architecture of finger millet and barnyard millet seedlings

Millets, as key crops in semi-arid and arid tropical regions, are gaining recognition for their nutritional benefits and resilience to challenging conditions. Finger millet and barnyard millet, in particular, stand out for their nutrient profiles and adaptability. However, research on their response to waterlogging, a major abiotic stress, remains limited. This study aimed to examine the immediate response of finger millet and barnyard millet seedlings to transient waterlogging conditions, focusing on their growth patterns and changes in root architecture to understand their morpho-physiological adaptive strategy. Seedlings were subjected to varying durations of waterlogging: control, 48, 74, and 120 hours to assess parameters such as shoot and root characteristics, leaf growth, and tolerance indices. Results showed a decrease in root length and an increase in shoot length with prolonged waterlogging. Root and shoot biomass, along with seedling dry weight, rose as waterlogging durations increased. Significant increases were observed in root surface area, volume, and the number of root tips and forks. Leaf area initially expanded but declined after 72 hours of waterlogging, accompanied by changes in specific leaf area and chlorophyll concentration. Tolerance indices, such as root-to-shoot ratio, decreased under waterlogging conditions, with finger millet exhibiting higher tolerance than barnyard millet. These findings provide insights into the adaptive strategies of millets under waterlogging, which is valuable for crop management and breeding for enhanced stress tolerance.

The effects of the magnetic field on germination and seedling growth of chickpea (Cicer arietinum L.) and sunflower (Helianthus annuus L.)

Organisms interact with their environment and effects of environmental factors vary depending on ecology and tolerance levels. However magnetic field is an inevitable factor for all organisms. The aim of the study was to investigate the effects of different magnetic field (MF) applications on germination percentage, pigment content and antioxidant capacity of two important agricultural plant (Sunflower and Chickpea) species. Initially, seeds were exposed to 5 mT, 10 mT and 20 mT magnetic field generated by Helmholtz coil for detection of germination effects. Then seedling test was survived at the same conditions. MF was applied 20 minutes for every day at the same time period. According to germination results, MF application to sunflower and chickpea seeds was resulted with increase in germination percentage compared to control. 20 mT application caused decrease in shoot length of sunflower seedlings. On the contrary, 20 mT MF application resulted with increase in shoot length of chickpea seedlings. All magnetic field strengths increased carotenoid levels in chickpea seedlings. Also, MF application affected the phenolic and flavonoid contents of sunflower and chickpea seedlings. Depending on the increase in secondary metabolites, DPPH and FRAP activities varied. As a conclusion, MF application contributed to effect on plant metabolism and it has the potential to be used in agricultural applications.

Efficacy of soil drench and foliar application of iron nanoparticles on the growth and physiology of Solanum lycopersicum L. exposed to cadmium stress

Cadmium (Cd) can harm the yield and quality of vegetables, threatening food safety. Essential microelements such as iron are crucial for plant growth and can help alleviate heavy metal stress. Recently, nanoparticles have been studied as eco-friendly solutions for mitigating heavy metal stress in plants. In the present study, iron nanoparticles (FeNPs) at 0, 100, and 300 mg/L were applied as soil drenches and foliar sprays to tomato plants under cadmium stress. A comparison was made between the application methods of FeNPs by evaluating the growth parameters of tomato plants, including shoot length (SL), root length (RL), number of branches (NB), number of leaves per plant (NL), and leaf area (LA), as well as by assessing biochemical and antioxidant enzyme parameters. In the Cd stress treatment, the protein content decreased by 24.71%, and the phenolic and flavonoid content of the tomato plants also decreased due to cadmium stress, with levels decreasing from 16.07 to 6.9 µg and from 0.36 to 0.16 µg, respectively. Compared with the soil drench, 100 mg/L FeNPs significantly improved the parameters of Cd-stressed plants when used as a foliar spray, leading to increases in shoot length, root length, fruit weight, number of fruits, number of leaves, and number of branches by 42%, 66%, 24%, 66%, 173%, and 45%, respectively. Tomato plants treated with this spray presented increased carotenoid and lycopene contents. FeNP foliar spray also reduced Cd accumulation in plant tissues. This technique shows promise in alleviating Cd stress in vulnerable vegetable plants such as tomatoes.

Diurnal response of ecophysiological parameters in kiwifruit under photoselective pearl net

Background Agricultural adaptation to climate change is crucial, particularly in semi-arid and arid regions. Modern agriculture requires innovative strategies to protect crops from extreme weather events. Photoselective pearl net offers promise in mitigating environmental stresses in kiwifruit production, especially in Chile. Objective This study aims to characterize kiwifruit plants’ diurnal ecophysiological responses under photoselective pearl net. Materials The trial was conducted in a commercial kiwifruit orchard in Chile's Colchagua valley, focusing on ‘Hayward’ vines grown under a photoselective pearl net. A completely randomized design with two treatments (uncovered and covered) was employed. Meteorological parameters, canopy spectral reflectance, vegetative growth, and ecophysiological parameters were evaluated. Results Pearl netting reduced photosynthetically active radiation (PAR), leading to increased shoot length and leaf area. Despite the high variability of the diurnal response of the ecophysiological parameters, there were no significant differences in leaf water potential (ψx) and stomatal conductance (gs) between treatments. Conclusion Photoselective pearl net effectively modifies the light environment, enhancing vegetative growth without compromising key physiological functions. These findings suggest that photoselective netting can improve crop management practices and resilience to climatic variability.

Exploring the Potential of Bacillus subtilis IS1 and B. amyloliquificiens IS6 to Manage Salinity Stress and Fusarium Wilt Disease in Tomato Plants by Induced Physiological Responses.

The intensified concerns related to agrochemicals' ecological and health risks have encouraged the exploration of microbial agents as eco-friendly alternatives. Some members of Bacillus spp. are potential plant-growth-promoting agents and benefit numerous crop plants globally. This study aimed to explore the beneficial effects of two Bacillus strains (B. subtilis strain IS1 and B. amyloliquificiens strain IS6) capable of alleviating the growth of tomato plants against salinity stress and Fusarium wilt disease. These strains were able to significantly promote the growth of tomato plants and biomass accumulation in pot trials in the absence of any stress. Under salinity stress conditions (150 mM NaCl), B. subtilis strain IS1 demonstrated superior performance and significantly increased shoot length (45.74%), root length (101.39%), fresh biomass (62.17%), and dry biomass (49.69%) contents compared to control plants. Similarly, B. subtilis strain IS1 (63.7%) and B. amyloliquificiens strain IS6 (32.1%) effectively suppressed Fusarium wilt disease and significantly increased plant growth indices compared to the pathogen control. Furthermore, these strains increased the production of chlorophyll, carotenoid, and total phenolic contents. They significantly affected the activities of enzymes involved in antioxidant machinery and the phenylpropanoid pathway. Hence, this study effectively demonstrates that these Bacillus strains can effectively alleviate the growth of tomato plants under multiple stress conditions and can be used to develop bio-based formulations for use in the fields.

Characterization of mercury ameliorating rhizobacteria for enhancing growth and yield of Triticum aestivum L. in the field: An in-vitro and in- silico study

Mercury (Hg) resistant and indole 3-acetice acid (IAA)-producing rhizobacteria were isolated from mercury-contaminated areas. Among the 60 Hg-resistant bacterial isolates, three were selected based on high Hg-resistance (MIC-30 µg/ml) and IAA production (15–40 µg/ml). Selected isolates were subjected to biochemical and molecular characterization, and High-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC–MS) analyses were performed to confirm IAA production by these rhizobacteria. Pot and field experiments were conducted under controlled conditions on Triticum aestivum L. with a bacterial consortium consisting of AZ-3, Z-A15, and Z-A22. The selected isolates were identified as Bacillus cereus AZ-3, Enterobacter cloacae Z-A15, and Pseudomonas putida Z-A22, respectively. B. cereus AZ-3 showed 90 % resistance against HgCl2 at 40 µg/ml due to the presence merT gene. E. cloacae Z-A15 and P. putida Z-A22 showed high production of IAA at 20 and 36 µg/ml respectively. High-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC–MS) confirmed IAA production by the selected bacteria. In greenhouse experiments, the inoculation of T. aestivum L. with bacterial consortium A7 (AZ-3, Z-A15, and Z-A22) with Hg resulted in 35 %, 60 %, 22 %, 98 % and 100 % increase while without Hg showed 32 %, 60 %, 30 %, 56 %, and 120 % increase in shoot length, tillers, spike length, number of spikelets, and seed weight/200 g respectively. In field experiments, the A7 showed 17 %, 66 %, 17 %, 27 %, 40 % and 70 % increases in shoot length, tillers, spike length, number of spikelets, dry weight and yield/acre in T. aestivum L. respectively (p < 0.05). The structural determination of MerT protein of B. cereus AZ-3 was carried out using bioinformatics tools, i.e., DISOPRED, SwissModel, ERRAT, Verify3D and PROCHECK. These tools predicted the structural-based functional homology of MerT transmembrane protein in bacterial Hg-detoxification system. The use of the bacterial consortium A7 as a biofertilizer to reduce mercury pollution while promoting plant growth in contaminated soils offers a novel approach to maintaining sustainable agricultural land in polluted environments.

Calcium oxide nanoparticles ameliorate cadmium toxicity in alfalfa seedlings by depriving its bioaccumulation, enhancing photosystem II functionality and antioxidant gene expression

Cadmium (Cd) is a highly toxic and carcinogenic pollutant that poses significant risks to living organisms and the environment, as it is absorbed by the plant roots and accumulates in different parts of crop during its production. A promising sustainable strategy to counteract these threats to use calcium oxide nanoparticles (CaO-NPs) as soil supplements in fodder crops. This approach has shown notable morpho-physiological and biochemical improvements under metal toxicity conditions. However, the specific mechanisms driving Cd tolerance, particularly at physio-biochemical level and antioxidant related genes expression in fodder crops including alfalfa remain unexplored. CaO-NPs supplementation can trigger various signaling pathways that lead to enhance the photosynthetic pigments formation, stomatal conductance, CO2 assimilation rate and quantum yield of photosystem II. In this study, we evaluated various doses of CaO-NPs (0, 25, 50, and 100 mg kg−1) for their efficacy in reducing Cd bioavailability and toxicity in alfalfa plants. Our results demonstrated that Ca2+ and Cd2+, which share the same ionic radius, compete for ion transport through channels. The small size and high availability of CaO-NPs facilitate their rapid translocation within plant tissues, reducing metal uptake by 61 % in shoots and 30 % in roots. Notably, application of CaO-NPs at 100 mg kg−1 significantly increased shoot length (44 %) and root length (35 %) as compared to Cd-treated control plants. The highest dose of CaO-NPs also improved photosynthetic efficiency and gas exchange attributes including gs, Tr, Pn and Ci by 66 %, 27 %, 33 % and Ci 21 %, respectively, compared with the Cd treated control. Moreover, CaO-NPs (at 100 mg kg−1) alleviated metal-induced oxidative stress by boosting antioxidant enzyme activities like superoxide dismutase (25 %) peroxidase (42 %), catalase (72 %) and ascorbate peroxidase (87 %) and diminishing reactive oxygen species (ROS) production when compared with sole Cd treatment. Scanning and transmission electron microscopy revealed that CaO-NPs positively impacted stomatal conductance and mitigated Cd toxicity in leaf ultrastructure. Additionally, the highest dose of CaO-NPs markedly upregulated the expression of antioxidant-related genes, MsCu/Zn SOD, MtPOD, MtCAT, and MtAPX in roots and shoots by 0.67 and 1.03 fold-change (FC), 0.61 and 0.53 FC, 0.54 and 0.88 FC, and 0.46 and 0.66 FC, respectively. In conclusion, CaO-NPs demonstrate significant potential for environmentally friendly mitigation of Cd stress in alfalfa by reducing its uptake, thereby supporting sustainable agriculture.

Effect of different concentrations of soil and foliar applied zinc, boron and iron fertilizers on seedling growth, chlorophyll content and productivity of chickpea seedlings under semi-arid environment

The effectiveness of zinc (Zn), boron (B), and iron (Fe) is reduced in semi-arid regions, which can lead to a deficiency of these nutrients and inhibit chickpea productivity. In this work, three field experiments were executed over two years where soil and foliar applications of Zn, B, and Fe were carried out, including controls (Zn0, B0, and F0), soil application at 4.125 kg/ha (Zn-1, B1, and F1) and 8.25 kg/ha (Zn-2, B2, and F2), and foliar spay at 0.3% at flowering initiating (Zn-3, B3, and F3) and one week after flowering initiation (Zn-4, B4, and F4, respectively). The results indicate that the deficiency of these nutrients inhibited chickpea growth and yield, leading to a reduction in the pigment contents. Nonetheless, soil and foliar application of Zn, B, and Fe significantly improved growth, chlorophyll contents, and yield, showing a dose-dependent effect. The best results were recorded for Zn-3, B2, and F2 treatments which significantly (P&lt;0.05) increased shoot length (20.96-85.19%), root length (42.85-93.65%), shoot fresh (23-76%) and root fresh weight (45-90.32%), compared with the control treatment. Chlorophyll parameters, including chlorophyll a and b contents, showed similar trends. Zn-3, B2, and F2 treatments significantly increased biological and grain yields, which were associated with higher values of the number of pods per plant and the number of seeds per pod. In a nutshell, we suggest that Zn foliar application at 0.3% at flowering initiation and soil application of B and Fe at 25 kg/ha are beneficial for improving the growth, pigment content, and overall productivity of chickpea.

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.

Optimizing mycorrhizal fungi application for improved nutrient uptake, growth, and disease resistance in cardamom seedlings (Elettaria cardamomum (L.) Maton)

This study evaluated the impact of various doses (5, 10, 15 g) and application sequences (1, 2, or 3 times at monthly intervals) of arbuscular mycorrhizal (AM) fungal inoculum on cardamom seedlings over two years (2020–2021 and 2021–2022). The results indicated that the dosage of AM inoculum had a more substantial effect on the seedlings than the application sequence. A 10 g dose significantly increased shoot length and dry weight, while three applications of 5 g each improved the number of fibrous roots. Although potassium uptake was not affected, phosphorus and calcium uptake were highest with the 10 g dose. Arbuscular mycorrhizal inoculation also enhanced phosphatase activity in the rhizosphere, with 5 g improving acid phosphatase and 10 g improving alkaline phosphatase activity. Disease incidence, including seedling rot was lower with the 10 g dose, and additional sequential applications did not further reduce disease. Structural equation modeling (SEM) revealed that AM colonization positively influenced dry weight through the number of fibrous roots, showing a strong relationship between AM dose, colonization, spore count, and mycorrhizal dependency. This study indicates that applying a 10 g dose of AM fungal inoculum can be particularly beneficial in agroecosystems for improving cardamom seedling growth, nutrient uptake, and disease resistance.

Co-application of Parthenium biochar and urea effectively mitigate cadmium toxicity during wheat growth

Environmental contamination by cadmium (Cd), a highly toxic heavy metal, poses significant health risks to plants and humans. Biochar has been effectively used to promote plant growth and productivity under Cd stress. This study presents an innovative application of biochar derived from the invasive weed Parthenium hysterophorus to promote plant growth and productivity under Cd stress. Our study includes detailed soil and plant analyses, providing a holistic perspective on how biochar and urea amendments influence soil properties, nutrient availability, and plant physiological responses. To address these, we established seven treatments: the control, Cd alone (5 mg kg−1), biochar alone (5 %), urea alone (3 g kg−1), biochar with Cd, urea with Cd, and a combination of biochar and urea with Cd. Cd stress alone significantly reduced plant growth indicators such as shoot and root length, fresh and dry biomass, chlorophyll content, and grain yield. However, the supplementation of biochar, urea, or their combination significantly increased shoot length (by 48%, 34%, and 65%), root length (by 73%, 46%, and 70%), and fresh shoot biomass (by 4%, 31%, and 4%), respectively. This improvement is attributed to enhanced soil properties and improved nutrient absorption. The biochar–urea combination also enhanced Cd tolerance by improving total chlorophyll content by 14 %, 13 %, and 16 % compared to the control, respectively. Similaly, these treatments significantly (p < 0.05) boosted the activity of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase by 51 %, 30 %, and 51 %, respectively, thereby mitigating oxidative stress as a defensive mechanism. The Cd tolerance was improved by biochar, urea, and their combinations, which reduced Cd content in the shoots (by 60.5 %, 38.9 %, and 51.3 %), roots (by 47.5 %, 23.9 %, and 57.6 %), and grains (by 58.1 %, 30.2 %, and 38.3 %) relative to Cd stress alone, respectively. The synergistic effects of biochar and urea are achieved through improved soil properties, nutrient availability, activating antioxidant defense mechanisms, and minimizing the accumulation of metal ions in plant tissues, thereby enhancing plant defenses against Cd stress. Conclusively, converting invasive Parthenium weed into biochar and combining it with urea offers an environmentally friendly solution to manage its spreading while effectively mitigating Cd stress in crops.

Rhizofungus Aspergillus terreus Mitigates Heavy Metal Stress-Associated Damage in Triticum aestivum L.

Industrial waste and sewage deposit heavy metals into the soil, where they can remain for long periods. Although there are several methods to manage heavy metals in agricultural soil, microorganisms present a promising and effective solution for their detoxification. We isolated a rhizofungus, Aspergillus terreus (GenBank Acc. No. KT310979.1), from Parthenium hysterophorus L., and investigated its growth-promoting and metal detoxification capabilities. The isolated fungus was evaluated for its ability to mitigate lead (25 and 75 ppm) and copper (100 and 200 ppm) toxicity in Triticum aestivum L. seedlings. The experiment utilized a completely randomized design with three replicates for each treatment. A. terreus successfully colonized the roots of wheat seedlings, even in the presence of heavy metals, and significantly enhanced plant growth. The isolate effectively alleviates lead and copper stress in wheat seedlings, as evidenced by increases in shoot length (142%), root length (98%), fresh weight (24%), dry weight (73%), protein content (31%), and sugar content (40%). It was observed that wheat seedlings possess a basic defense system against stress, but it was insufficient to support normal growth. Fungal inoculation strengthened the host's defense system and reduced its exposure to toxic heavy metals. In treated seedlings, exposure to heavy metals significantly upregulated MT1 gene expression, which aided in metal detoxification, enhanced antioxidant defenses, and maintained metal homeostasis. A reduction in metal exposure was observed in several areas, including normalizing the activities of antioxidant enzymes that had been elevated by up to 67% following exposure to Pb (75 mg/kg) and Cu (200 mg/kg). Heavy metal exposure elevated antioxidant levels but also increased ROS levels by 86%. However, with Aspergillus terreus colonization, ROS levels stayed within normal ranges. This decrease in ROS was associated with reduced malondialdehyde (MDA) levels, enhanced membrane stability, and restored root architecture. In conclusion, rhizofungal colonization improved metal tolerance in seedlings by decreasing metal uptake and increasing the levels of metal-binding metallothionein proteins.

Spirulina biomass loaded with iron nanoparticles: A novel biofertilizer for the growth and enrichment of iron content in rice plants

The current investigation was focused to develop a nano-iron-based phycofertilizer to enhance crop quality in an environment-friendly manner. Biosynthesis of nano-iron occurred when Spirulina biomass was exposed to a 0.05M FeCl3 solution for 48h at pH 5.5 in the dark, resulting in the synthesis of spindle-shaped nano-iron both inside and outside the cells. The particles' sizes were 24.77 ± 5.264 nm as observed in transmission electron microscopy. Further characterizations were carried out using energy dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS). The performance of various fertilizers, including those derived from phycosynthesized nano iron (INP), dried Spirulina biomass (SB), and nano-iron loaded Spirulina biomass i.e., nano-phycho-fertilizer (NPF) was compared against conventional NPK fertilizer. The results from field applications indicated significant improvements in rice, with NPF outshining the rest. Notably, NPF demonstrated a remarkable 37.6% increase in shoot length, a 47% boost in crop productivity, and a 15% rise in grain weight of rice compared to NPK. Both unpolished and polished grains of NPF-treated plants contained higher iron contents (44% and 28%) than the NPK-treated plants. Furthermore, the cost-effectiveness analysis underscored the superiority of NPF over conventional fertilizer, representing it as a highly effective and eco-friendly nano-iron-based phycofertilizer.

Enhancing Zea mays L. seedling growth with He[sbnd]Ne laser-irradiated Alcaligenes sp. E1 to mitigate salinity stress

Plant growth-promoting rhizobacteria (PGPR) are a beneficial strategy to improve agriculture and mitigate abiotic stress. To increase the efficacy of this approach, the utilization of HeNe laser radiation (L) and methylene blue (MB) as photosensitizer is commonly suggested. This study evaluated the role of the IAA-producing rhizobacterial strain Alcaligenes sp. E1 on maize growth under salt stress (150 mM NaCl) with the application of laser and methylene blue. The results showed that treatment of Alcaligenes sp. E1 with red laser and methylene blue exhibited a maximum increase in shoot length (44 %), root length (49 %), fresh weight (34 %), dry weight (45.6 %), chlorophyll a (51 %), and carotenoids (71 %) over the stressed control. In addition, it demonstrated more activity to antioxidant activities (SOD, CAT, GSH, and TAC) and limited oxidative damage resulting from ROS formation. In conclusion, Alcaligenes sp. has a good ability to stimulate maize growth when applied with laser radiation and photosensitizer under normal and saline conditions. Thus, we propose that red laser and photosensitizer will have promising applications in crop biostimulation and sustainable agriculture.

Soil microbiomes from the groundnut basin of Senegal contain plant growth-promoting bacteria with potential for crop improvement in arid soils.

The principal methods to maintain soil fertility in Sahel soils are largely allowing fields to go fallow and manure addition. These methods are not currently sufficient to improve soil fertility. To promote biological amendments, we aimed to understand the plant-growth promoting traits of various soil microbial isolates. The soils collected in different areas in Senegal exhibited a similar eDNA profile of bacteria; the dominant microbes were Firmicutes, followed by Proteobacteria and Actinobacteria. Of 17 isolates identified and tested, the vast majority solubilized rock phosphate and a large number grew on culture medium containing 6% salt, but very few degraded starches or hydrolysed carboxymethyl cellulose or produced siderophores. Upon single inoculation, Peribacillus asahii RC16 and Dietzia cinnamea 55 significantly increased pearl millet growth and yield parameters. For cowpea, plant shoot length was significantly increased by Pseudarthrobacter phenanthrenivorans MKAG7 co-inoculated with Bradyrhizobium elkanii 20TpCR5, and nearly all rhizobacteria tested significantly improved cowpea dry weight and pod weight. Additionally, the double inoculation of Dietzia cinnamea 55 and MKAG7 significantly increased shoot length, dry weight, and seed head weight of pearl millet. These isolates are promising inoculants because they are ecologically-friendly, cost-effective, sustainable, and have fewer negative effects on the soil and its inhabitants.

Insights into trehalose mediated physiological and biochemical mechanisms in Zea mays L. under chromium stress

BackgroundChromium (Cr) toxicity significantly threatens agricultural ecosystems worldwide, adversely affecting plant growth and development and reducing crop productivity. Trehalose, a non-reducing sugar has been identified as a mitigator of toxic effects induced by abiotic stressors such as drought, salinity, and heavy metals. The primary objective of this study was to investigate the influence of exogenously applied trehalose on maize plants exposed to Cr stress.ResultsTwo maize varieties, FH-1046 and FH-1453, were subjected to two different Cr concentrations (0.3 mM, and 0.5 mM). The results revealed significant variations in growth and biochemical parameters for both maize varieties under Cr-induced stress conditions as compared to the control group. Foliar application of trehalose at a concentration of 30 mM was administered to both maize varieties, leading to a noteworthy reduction in the detrimental effects of Cr stress. Notably, the Cr (0.5 mM) stress more adversely affected the shoot length more than 0.3mM of Cr stress. Cr stress (0.5 mM) significantly reduced the shoot length by 12.4% in FH-1046 and 24.5% in FH-1453 while Trehalose increased shoot length by 30.19% and 4.75% in FH-1046 and FH-1453 respectively. Cr stress significantly constrained growth and biochemical processes, whereas trehalose notably improved plant growth by reducing Cr uptake and minimizing oxidative stress caused by Cr. This reduction in oxidative stress was evidenced by decreased production of proline, SOD, POD, MDA, H2O2, catalase, and APX. Trehalose also enhanced photosynthetic activities under Cr stress, as indicated by increased values of chlorophyll a, b, and carotenoids. Furthermore, the ameliorative potential of trehalose was demonstrated by increased contents of proteins and carbohydrates and a decrease in Cr uptake.ConclusionsThe study demonstrates that trehalose application substantially improved growth and enhanced photosynthetic activities in both maize varieties. Trehalose (30 mM) significantly increased the plant biomass, reduced ROS production and enhanced resilience to Cr stress even at 0.5 mM.