Reduced Plant Growth Research Articles

Plant growth, Yield and Leaf Nutritional value of Jute (Corchorus olitorius L.) as Influenced by Banana Peel levels under Salt Stress conditions in Coastal region of Cameroon

In the world, millions of hectares of cultivated land are affected by salt, making salinity a major constraint for plant production. The effects of different levels of banana peel on growth, yield, and chemical changes of jute (Corchorus olitorius L.) under salt stress were examined herein. Response of jute to applications of different levels of banana peel (5, 10, and 15 t ha-1), as well as water irrigation salinity at 50, 100, and 200 mM NaCl were evaluated under greenhouse conditions. The outcome uncovered that salinity caused significant reduction of plant growth and yield parameters, chlorophyll (at 21.6%), LRWC (at 18.9%), P (at 57.1%) and K (at 45.4%) content, while MDA content (at 351.8%), Na (at 266%), soluble proteins (70.2%), total phenolic (at 23.4%) accumulation showed an increase from 0 to 200 mM NaCl without BP application. The banana peel treatments (at 15 t ha-1 under 200 mM NaCl) diminished significantly damaging effects caused by salinity via a reduction in the Na (at 28.4%), total soluble sugars (at 17.8%), total flavonoids (at 20.1%), which enhanced number of leaves per plant (37.1%), plant height (at 19.8%), leave yield (at 41.4%), LRWC (at 12.8%), Mg (at 24.2%) and reduced the MDA content (at 20%), presenting a favorable effect in reducing the oxidative stress that emerged from salt stress. It could be concluded, that the application of 15 t ha-1 of BP was superior in promoting plant growth, yield, and nutritional quality than others under control and in the saline soils in this study. BP at 15 t ha-1 had a more reduced damage of salt stress effect on growth, yield, nutritional value, and use efficiency.

Optimizing seedling production for the conservation of the threatened Dyckia rariflora (Bromeliaceae)

ObjectivesIn vitro seed propagation can enhance plant species growth and enable the rapid production of seedlings while preserving genetic variability. This study aimed to develop in vitro seed propagation and acclimatization protocols for Dyckia rariflora to support conservation efforts of this bromeliad endemic to ferruginous campos rupestres. Seed germination and plant growth were tested using MS (Murashige & Skoog) culture medium with varying salt concentrations, sucrose levels, and the presence or absence of polyvinylpyrrolidone (PVP). Following these treatments, seedlings were acclimatized after removal from the controlled environment.ResultsGermination rates varied between 65 and 90%, unaffected by treatment. The highest germination speed index was in half MS salts without PVP, while full MS salts, sucrose, and PVP slowed germination. Half MS salts resulted in seedlings with greater height, more leaves, and longer roots. Complete MS salts were less effective. No seed oxidation was observed. After 120 days of acclimatization, survival rates exceeded 70%, with plants in half MS salts and 15 g sucrose showing the best growth. In vitro propagation of D. rariflora is viable for large-scale plant production, with half MS salt and sucrose concentrations, without PVP, recommended for better plant growth and cost reduction.

Humic substances increase tomato tolerance to osmotic stress while modulating vertically transmitted endophytic bacterial communities.

While humic substances (HS) are recognized for their role in enhancing plant growth under abiotic stress by modulating hormonal and redox metabolisms, a key question remains: how do HS influence the microbiota associated with plants? This study hypothesizes that the effects of HS extend beyond plant physiology, impacting the plant-associated bacterial community. To explore this, we investigated the combined and individual impacts of HS and osmotic stress on tomato plant physiology and root endophytic communities. Tomatoes were grown within a sterile hydroponic system, which allowed the experiment to focus on seed-transmitted endophytic bacteria. Moreover, sequencing the 16S-ITS-23S region of the rrn operon (~4,500 bp) in a metabarcoding assay using the PNA-chr11 clamp nearly eliminated the reads assigned to Solanum lycopersicum and allowed the species-level identification of these communities. Our findings revealed that HS, osmotic stress, and their combined application induce changes in bacterial endophytic communities. Osmotic stress led to reduced plant growth and a decrease in Bradyrhizobium sp., while the application of HS under osmotic stress resulted in increased tomato growth, accompanied by an increase in Frigoribacterium sp., Roseateles sp., and Hymenobacter sp., along with a decrease in Sphingomonas sp. Finally, HS application under non-stress conditions did not affect plant growth but did alter the endophytic community, increasing Hymenobacter sp. and decreasing Sphingomonas sp. This study enhances the understanding of plant-endophyte interactions under stress and HS application, highlighting the significance of the vertically transmitted core microbiome in tomato roots and suggesting new insights into the mode of action of HS that was used as a biostimulant.

Deciphering Whether Illite, a Natural Clay Mineral, Alleviates Cadmium Stress in Glycine max Plants via Modulation of Phytohormones and Endogenous Antioxidant Defense System

Globally, cadmium (Cd) stress dramatically reduces agricultural yield. Illite, a natural clay mineral, is a low-cost, environmentally acceptable, new promising method of reducing the heavy metal (HM) stress of cereal crops. In research statistics, there is little research on stress tolerance behavior of Illite (IL) on an experimental soybean plant. In the present study, we took IL and examined it for tolerance to Cd, as well as for other plant-growth-promoting (PGP) characteristics in Glycine max (soybean). The results showed that applying clay minerals in different concentrations enhanced the level of SA (defense hormone) and reduced the level of ABA (stress hormone). Cd 1 mM significantly reduces plant growth by altering their morphological characteristics. However, the application of IL significantly enhanced the seedling characteristics, such as root length (RL), 29.6%, shoot length (SL), 14.5%, shoot fresh biomass (SFW), 10.8%, and root fresh biomass (RFB), 6.4%, in comparison with the negative control group. Interestingly, IL 1% also enhanced the chlorophyll content (C.C), 15.5%, and relative water content (RWC), 12.5%, in all treated plants. Moreover, it resulted in an increase in the amount of superoxide dismutase (SOD), phenolics, and flavonoids in soybean plants, while lowering the levels of peroxidase (POD) and H2O2. Furthermore, compared to control plants, soybean plants treated with the Illite exhibited increased Si absorption and lower Cd levels, according to inductively coupled plasma mass spectrometry (ICP-MS). Thus, the IL can operate as an environmentally beneficial biofertilizer and sustainable approach under Cd stress by promoting plant development by activating signaling events.

Modulatory effects of glutamic acid on growth, photosynthetic pigments, and stress responses in olive plants subjected to cadmium stress

Cadmium (Cd) is a toxic heavy metal that severely impacts plant growth and photosynthesis and induces oxidative stress. This study investigates the modulatory effects of glutamic acid (GA) on Olea europaea (olive) seedlings subjected to cadmium stress. The experiment included control, Cd-stressed, GA-treated, and combined Cd and GA-treated groups. Cd exposure significantly reduced plant growth, as evidenced by decreased root length (3.5 cm) and shoot length (9 cm) compared to control plants (5 cm and 12 cm, respectively). Additionally, Cd stress led to a reduction in chlorophyll content (16.2 mg/g fresh weight) and elevated oxidative markers like H2O2 and MDA. The application of GA significantly improved plant growth and physiological parameters, with statistically significant increases in root length (up to 6.5 cm) and shoot length (up to 14 cm) in the combined treatment group (p ≤ 0.05). Furthermore, GA treatment led to a marked elevation in total chlorophyll content (up to 27.5 mg/g fresh weight), compared to 16.2 mg/g in Cd-stressed plants (p ≤ 0.05), reflecting a significant improvement in photosynthetic efficiency. GA also elevated the antioxidant enzyme activity catalase (CAT) and peroxidase (POD), reducing oxidative stress by decreasing hydrogen peroxide and MDA levels. The findings suggest that glutamic acid effectively mitigates Cd-induced phytotoxicity, enhancing stress resistance and promoting plant growth. This research provides valuable insights into using glutamic acid as a possible approach to mitigate heavy metal stress in plants, offering implications for agriculture and environmental management in Cd-contaminated areas. Specific applications may include its use in phytoremediation practices or as a supplement in agricultural management to improve crop resilience in polluted environments. Further research could explore the molecular mechanisms underlying GA’s protective effects and its potential synergy with other biostimulants to enhance heavy metal tolerance in a broader range of crops.

Evaluation of herbicidal potential of Siderophores produced by Amycolatopsis lurida strain 407

The urgent need for sustainable agriculture has intensified the search for environmentally friendly alternatives to chemical herbicides. This study investigates the herbicidal potential of siderophores produced by Amycolatopsis lurida strain 407, focusing on its effects on the growth of ryegrass and redroot weeds. Strain 407 exhibited two distinct colony morphologies—red and white—when cultured under varying environmental conditions. The cell-free culture filtrate (CFCF) from both colony types significantly inhibited the growth of ryegrass and redroot. The concentration of siderophore produced in the iron-deficient medium was measured to be 613.4 ppm for 407 red and 388.5 ppm for 407 white, which indicates significant iron chelating activity. This study also showed a direct relationship between the presence of siderophore in plant culture medium and reduced growth. Also, analysis of fractions of the aqueous phase resulting from column chromatography revealed that all fractions from the 407 red reduced ryegrass shoot length by up to 45% and root length by 83–86%, while redroot seedling length decreased by up to 36%. Fractions from 407 white completely inhibited germination or reduced ryegrass root length by up to 94% and redroot seedling length by 52%. Fractions F4 W to F7 W and F2 R to F8 R, which showed iron chelating activity were most effective in reducing plant growth, suggesting that there are metabolites, alone or in company with siderophores, synergistically do herbicidal activity. The innovative application of siderophores as bioherbicide presents a promising environmentally friendly alternative to chemical herbicides.

Mitigating the Adverse Effects of Salt Stress on Pepper Plants Through Arbuscular Mycorrhizal Fungi (AMF) and Beneficial Bacterial (PGPR) Inoculation

This study investigates arbuscular mycorrhizal fungi (AMF), plant growth-promoting rhizobacteria (PGPR), and their combined application under salt stress (200 mM NaCl), emphasizing their synergistic potential to enhance plant resilience. Conducted in a controlled climate chamber, key parameters such as plant height, biomass, SPAD values, ion leakage, relative water content (RWC), osmotic potential, and mineral uptake were assessed. Salt stress significantly reduced plant growth, chlorophyll content, and nutrient absorption. However, AMF and PGPR improved plant performance, with co-inoculation showing the highest efficacy in increasing RWC, nutrient uptake, and maintaining membrane stability. AMF and PGPR treatments enhanced potassium retention and reduced sodium and chloride accumulation, mitigating ionic imbalances. The improved chlorophyll content and water relations under co-inoculation demonstrate the potential of these biostimulants to boost photosynthesis and plant resilience. These findings highlight AMF and PGPR as eco-friendly solutions for sustainable agriculture, promoting crop productivity and stress tolerance under saline conditions.

Downregulation of the rice HRS1 HOMOLOG3 transcriptional repressor gene due to N deficiency directly co-activates ammonium and phosphate transporter genes.

Rice HRS1 HOMOLOG3 (OsHHO3) acts as a transcriptional repressor of AMMONIUM TRANSPORTER1 (OsAMT1) genes in rice; thus, reduced OsHHO3 expression in nitrogen (N)-deficient environments promotes ammonium uptake. In this study, we show that OsHHO3 also functions as a repressor of a specific subset of phosphate (Pi) transporter (PT) genes involved in the uptake and root-to-shoot translocation of Pi, including OsPT2, OsPT4, and OsPHO1;1. Consistently, disruption of OsHHO3 increased Pi uptake and Pi contents in shoots and roots, while overexpression of OsHHO3 generated the opposite effects. Furthermore, phosphorus (P) deficiency slightly decreased OsHHO3 expression, upregulating a specific subset of PT genes. However, N deficiency was more effective than P deficiency in suppressing OsHHO3 expression in roots, and unlike N deficiency-dependent activation of PT genes under the control of OsHHO3, the P deficiency-dependent activation of OsAMT1 genes was minimal. Interestingly, the simultaneous deficiency of both N and P promoted the OsHHO3-regulated expression of PT genes more significantly than the deficiency of either N or P, but diminished the expression of genes regulated by OsPHR2, a master regulator of Pi starvation-responsive transcriptional activation. Phenotypic analysis revealed that the inactivation and overexpression of OsHHO3 improved and reduced plant growth, respectively, under N-deficient and P-deficient conditions. These results suggest that OsHHO3 regulates a specific subset of PT genes independently of OsPHR2-mediated regulation and plays a critical role in the adaptation to diverse N and P environments.

A novel LRR receptor-like kinase BRAK reciprocally phosphorylates PSKR1 to enhance growth and defense in tomato

Plants face constant threats from pathogens, leading to growth retardation and crop failure. Cell-surface leucine-rich repeat receptor-like kinases (LRR-RLKs) are crucial for plant growth and defense, but their specific functions, especially to necrotrophic fungal pathogens, are largely unknown. Here, we identified an LRR-RLK (Solyc06g069650) in tomato (Solanum lycopersicum) induced by the economically important necrotrophic pathogen Botrytis cinerea. Knocking out this LRR-RLK reduced plant growth and increased sensitivity to B. cinerea, while its overexpression led to enhanced growth, yield, and resistance. We named this LRR-RLK as BRAK (B. cinerea resistance-associated kinase). Yeast two-hybrid screen revealed BRAK interacted with phytosulfokine (PSK) receptor PSKR1. PSK-induced growth and defense responses were impaired in pskr1, brak single and double mutants, as well as in PSKR1-overexpressing plants with silenced BRAK. Moreover, BRAK and PSKR1 phosphorylated each other, promoting their interaction as detected by microscale thermophoresis. This reciprocal phosphorylation was crucial for growth and resistance. In summary, we identified BRAK as a novel regulator of seedling growth, fruit yield and defense, offering new possibilities for developing fungal disease-tolerant plants without compromising yield.

Proteomic Analysis to Understand the Promotive Effect of Ethanol on Soybean Growth Under Salt Stress.

Finding solutions to mitigate the impact of salinity on crops is important for global food security because soil salinity significantly reduces plant growth and grain yield. Ethanol may play an important role in mitigating the negative salt-induced effects on crops. Soybean root growth was significantly reduced under salt stress; however, it was restored and comparable to control values by ethanol application even under stress. To study the positive mechanism of ethanol on soybean growth, a proteomic approach was carried out. The categories with the greatest changes in protein numbers were protein metabolism, transport, and cell organization in biological processes, nucleus and cytosol in cellular components, and nucleic acid binding activity in molecular functions. Proteomic data were confirmed using immunoblot analysis. Reactive oxygen species enzymes increased under salt stress; among them, mitochondrial ascorbate peroxidase was further accumulated by ethanol application. Among the cell wall and membrane-associated proteins, xyloglucan xyloglucosyl transferase and H+-ATPase increased and decreased, respectively, under salt stress; however, they were restored to control levels by ethanol application. These results suggest that soybeans were adversely affected by salt stress and recovered with ethanol application via the regulation of cell wall and membrane functions through the detoxification of reactive oxygen species.

Evaluating the effects of rice husk derived nanosilica on growth, photosynthesis, and antioxidant activity in hybrid maize

Drought stress was exacerbated by changing climatic conditions and impact the plant water relations from the cellular to whole plant level, thereby reducing the crop productivity and causing economic losses in agriculture. The present study was aimed to explore the potentials of nanosilica synthesized from rice husk in improving growth and drought stress tolerance in maize. Synthesized nanosilica from rice husk has spherical morphology, amorphous structure, siloxane bonding and higher purity (99.1 %). Soil application of varied levels of synthesized nanosilica (0, 5, 10, 15, 20, 30 and 40 mg kg−1) was tested with hybrid maize plants grown under irrigated and drought stress (100 and 50 % field capacity, respectively). The results of the study revealed that, drought stress has adverse effect on plant growth, biomass production and physiological parameters. However soil application of nanosilica has significantly improved growth, physiological and biochemical attributes of both irrigated and drought stressed plants. Nanosilica application at 20 mg kg−1 for irrigated and 30 mg kg−1 for drought stressed hybrid maize plants has recorded higher plant height, biomass, chlorophyll a, chlorophyll b, superoxide dismutase, peroxidase, phenols, soluble proteins and considerably decreased the proline, electrolyte leakage and melondialdehyde content in hybrid maize. In contrary, higher doses of nanosilica (>30 mg kg−1) caused a slight reduction in plant growth and antioxidant activity under both the water regimes. Hence, we conclude that, soil application of 20 and 30 mg kg−1 nanosilica synthesized from rice husk had a positive effect on plant growth and development besides aided in mitigating drought stress.

Ameliorating arsenic and PVC microplastic stress in barley (Hordeum vulgare L.) using copper oxide nanoparticles: an environmental bioremediation approach

The present study investigates the impact of varying concentrations of PVC microplastics (PVC–MPs) – specifically 0 (no PVC–MPs), 2, and 4 mg L− 1 –alongside different arsenic (As) levels of 0 (no As), 150, and 300 mg kg− 1 in the soil, with the concurrent application of copper oxide–nanoparticles (CuO–NPs) at 0 (no CuO –NPs), 25 and 50 µg mL− 1 to barley (Hordeum vulgare L.) plants. This research primarily aims to assess plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, as well as the response of various antioxidants (both enzymatic and non-enzymatic) and their relevant genes expression, proline metabolism, the AsA–GSH cycle, and cellular fractionation within the plants. The findings showed that increased levels of PVC–MPs and As stress in the soil significantly reduced plant growth and biomass, photosynthetic pigments, and gas exchange characteristics. Additionally, PVC–MPs and As stress increased oxidative stress in the roots and shoots, as evidenced by elevated levels of malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL), which in turn stimulated the production of various enzymatic and non-enzymatic antioxidants, gene expression, and sugar content. Furthermore, a notable increase in proline metabolism, the AsA–GSH cycle, and cellular pigmentation was observed. Conversely, the application of CuO–NPs resulted in a substantial improvement in plant growth and biomass, gas exchange characteristics, and the activity of enzymatic and non-enzymatic antioxidants, along with a reduction in oxidative stress. Additionally, CuO–NPs enhanced cellular fractionation while decreasing proline metabolism and the AsA-GSH cycle in H. vulgare plants. These outcomes provide new insights into sustainable agricultural practices and offer significant potential in addressing the critical challenges of heavy metal contamination in agricultural soils.

Development of Brassica carinata A. Braun resistant to acetolactate synthase–inhibiting herbicides

AbstractBrassica carinata A. Braun (carinata) has become an important oil crop for biofuel production in subtropical regions. Carinata is highly sensitive to acetolactate synthase (ALS)‐inhibiting herbicides, limiting its introduction into existing crop rotations. The objective of the study was to develop carinata lines resistant to ALS‐inhibiting herbicides. A susceptible carinata line was crossed with a resistant Brassica napus L. line. Lines derived from those crosses were screened at high doses of imidazolinones, which allowed identifying five lines with high levels of resistance. Doses to reduce plant growth 50% (GR50) and cause 50% injury (ID50) were four to nine times greater than susceptible lines. Resistant lines exhibited cross resistance with halosulfuron (sulfonylurea). Resistance was confirmed under field conditions with doses 2X and 4X for imazethapyr and 4X–8X for halosulfuron of their respective label doses. While susceptible lines died, resistant lines exhibited no injury or growth reductions compared with nontreated controls. Sequencing of the ALS gene indicated that all resistant lines carried a Trp574Leu amino acid substitution, a mutation responsible for resistance in other species. Crosses between resistant lines and a susceptible line demonstrated that the inheritance of the mutation corresponded with the resistance phenotype in the F2. The resistance trait behaved as a single, fully dominant allele, which makes it easier to transfer it to carinata lines with desirable agronomic traits. The resistant lines developed here provide flexibility for use in multiple crop rotations and opens the possibility to use ALS‐inhibiting herbicides for weed control within this crop's growing season.

OsPDIL1-5: dual role in promoting growth and development while modulating drought stress tolerance in rice (Oryza sativa L.).

Drought tolerance and plant growth are critical factors affecting rice yield, and identifying genes that can enhance these traits is essential for improving crop resilience and productivity. Using a growth-depressed and drought-tolerant (gddt) mutant of the indica rice variety Huanghuazhan (HHZ) generated by radiation mutagenesis, we discovered a novel gene, GDDT, which plays a dual role in plant biology: it acts as a positive regulator of growth and development, but as a negative regulator of drought resistance. The gddt mutant displayed a marked reduction in plant growth and seed setting rate, yet exhibited an unexpected advantage in terms of drought tolerance. Our research revealed that the enhanced drought tolerance of the gddt mutant is primarily due to a decrease in stomatal size, density, and aperture, which reduces water loss, and an activation of the reactive oxygen species (ROS) scavenging system, which helps protect the plant from oxidative stress. These physiological changes are observed both under drought conditions and in normal growth conditions. This discovery highlights the importance of GDDT as a pleiotropic gene with significant implications for both plant growth and drought resistance. Through map-based cloning, we determined that the protein disulfide isomerase-like (PDIL) gene OsPDIL1-5 is the GDDT gene. The protein encoded by this gene was localized to the endoplasmic reticulum, consistent with its predicted function. Our findings provide new insights into the role of PDIL genes in rice and suggest that further study of GDDT could lead to a better understanding of how these genes contribute to the complex interplay between plant growth, development, and stress responses. This knowledge could pave the way for the development of rice varieties that are more resilient to drought, thereby increasing crop yields and ensuring food security in water-limited environments.

Mitigation of salinity stress on morpho-physiological and yield related parameters of rice using different organic amendments

Salinity is a pernicious abiotic element that hinders crop development. Utilizing organic amendments to remediate salt is crucial for enhancing soil function and promoting crop growth. Based on this, a pot experiment was carried out at the research field of Khulna Agricultural University, Khulna, to examine the physiology, growth, and yield of transplanted aman rice in response to salinity stress using duckweed, and dhaincha biomass supplement. Excess salinity with no organic amendments reduced plant growth and development, relative water content (26%), and membrane stability (28%), index compared to T1 S1 (duckweed), and T2 S1 (dhaincha) at 50 mM salinity. Salinity delayed the emergence of first flowering and the maturity of filled grains. The lowest grain yield was recorded in T0S3 (no treatment + 100 mM salinity). Application of dhaincha and duckweed biomass ameliorates salinity individually at all salinity levels. Rice grown in saline soil with the application of T1 (duckweed biomass) and T2 (Sesbania biomass) had an 87% spikelet fertility while rice grown in soil without T1 and T2 treatment had only 21.82%. The application of T2 and T1 @ 5 t ha-1 increased grain yield by 33.29% and 4.70% compared to control. Furthermore, salinity stress @100 mM NaCl with duckweed decreased grain yield by 0.05% which was minimized to 12% by applying dhaincha green manure (T2) @ 5 t ha1. The finding showed that the ameliorative impact of green manure at 5 tha1 dose (T2) was more effective compared to the duckweed (T1) at the three salinity levels used in the study.

Efficacy of Bacillus spp. Isolates for Application as Biofertilizer in Tomato (Solanum lycospersicum L.) Cultivation

Certain species of Bacillus are considered rhizobacteria that promote plant growth, inhibit the growth of plant pathogens and deleterious rhizospheric microorganisms. The aim of this study was to determine the stimulatory effect of Bacillus subtilis KBM1 and Bacillus venezensis KBM1 on the growth and disease reduction of tomato plants in Côte d'Ivoire. In this respect, three substrates consisting of soil only, sawdust only and a mixture of soil and sawdust were inoculated with the two bacteria, then left to ferment for twenty-four (24) hours. The biofertilizers obtained after fermentation were used to assess their effects on the development of potted tomatoes. Growth parameters, infection rate and mortality rate of tomato plants were measured regularly during 6 weeks of cultivation. A search for tomato pathogenic fungi was carried out to demonstrate the efficacy of Bacillus strains isolates on plant health. The results obtained showed that Bacillus subtilis KBM1 and Bacillus venezensis KBM1 had a positive impact on plant growth of tomato plants grown. Infection and mortality rates of 0% were observed for tomato plants grown on the three substrates inoculated with these two bacteria. No pathogenic fungi were isolated from the organs of tomato plants grown on the three substrates fermented with the bacteria. However, on untreated control plants, a variety of pathogenic fungi, namely Fusarium sp, Phytophtora sp, Cladosporium sp, Rhizoctonia sp, Colletotrichum sp, Penicillium sp, Rhizopus sp and Trichoderma sp were observed. However, the Bacillus subtilis KBM1 treatment stood out from Bacillus venezensis KBM1 with the best results for the growth parameters measured. In view of these results, these two bacteria could be used to produce an effective biofertilizer for tomato cultivation in Côte d'Ivoire.

Salvia officinalis L. resilience under chromium stress: An integrated study of growth, physiology, biochemical changes and rosmarinic acid production

Medicinal plants are increasingly challenged by rising chromium (Cr) levels in agricultural soil and water bodies due to industrialization and human activities. This research examines the impact of various chromium concentrations on Salvia officinalis L., a medicinal herb, over 3 specific time periods: 30, 60 and 90 days. As the duration of Cr exposure increases, various growth parameters showed an upward trend at the lowest concentrations, with the most robust growth observed in the 20 ppm Cr treatment group after 90 days. However, higher chromium concentrations resulted in reduced plant growth compared to untreated plants. Chromium primarily accumulates in the roots, stems and leaves, with the highest accumulation observed at 100 ppm. However, chlorophyll content declined with prolonged Cr exposure, particularly at higher concentrations. Carbohydrate levels initially increased at lower Cr concentrations but decreased with greater exposure, while protein content consistently decreased with elevated Cr levels. Proline levels exhibited mixed responses, rising at lower concentrations and declining at higher ones. Malondialdehyde (MDA) content increased with higher Cr levels and extended exposure. The enzymatic antioxidant system showed an initial increase followed by a decline with prolonged exposure. Rosmarinic acid content increased with chromium (Cr) exposure upto 60 ppm but subsequently decreased beyond that threshold. In the first 30 days, plants treated with Cr demonstrated a 17 % increase in rosmarinic acid production compared to the control (48.9 mg/g DW). However, with continued Cr exposure, there was a decline in rosmarinic acid production ranging from 10 % to 20 % compared to the control level (67.02 mg/g DW) at 90 days post-treatment. These findings underscore the complex and contrasting responses of Salvia officinalis to Cr toxicity, highlighting the necessity for extended study into the core mechanisms governing these responses and the development of strategies to alleviate heavy metal stress in plants.

ROLE OF BIOTECHNOLOGY IN ABIOTIC STRESS TOLERANCE IN PLANTS

As population grows, abiotic stresses reduce plant growth and agricultural output, affecting global food security. Heat, cold, drought, salinity, and heavy metals affect crops. Heat stress from climate change disrupts cellular metabolism and lowers productivity. Tropical and subtropical crops suffer physiologically from cold stress. Climate variability affects drought, reducing crop output and germination. Salinity stunts growth and causes nutritional imbalances in big agricultural areas. Heavy metal buildup in soils threatens plant health. To overcome these problems, plants use osmotic adjustment, antioxidant defenses, and stress signaling pathways. CRISPR/Cas9 and other genetic engineering and molecular breeding methods may improve crop stress tolerance. Using omics technologies (genomics, transcriptomic, proteomics, and metabolomics) in breeding programs helps us understand stress tolerance processes and generate resilient crop types. This research is crucial for sustainable agriculture and global food security.

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.

Foliar application of rice husk derived nanosilica for mitigating drought stress in hybrid maize by boosting antioxidant defense system

The increasing frequency and intensity of drought magnified by the climate change, pose significant challenge to global food security and agricultural productivity. Chemically synthesized nanosilica have emerged as a promising solution for managing drought stress, enhancing crop growth and stress resilience but, its production involves harmful chemicals which results in adverse impacts on soil, plant and environment. Hence, the present study aimed to green synthesize and characterize silicon nanoparticles from rice husk and to evaluate their potential for improving plant growth, development and stress mitigation in hybrid maize. The rice husk derived nanosilica has spherical morphology, amorphous nature, siloxane bonds and high purity (99 %). Five different levels of nanosilica (0.05, 0.10, 0.15, 0.20 and 0.25 %) were sprayed on hybrid maize grown under irrigated and drought conditions and the results revealed that, nanosilica spray has improved the stress tolerance, growth and photosynthetic parameters. An optimum response was noted with the nanosilica spray upto 0.10 % in irrigated plants and 0.15 % in drought stressed plants, where greater increase in plant height (27.7 and 28.9 %), total biomass (55.7 and 39.1 %), chlorophyll a (36.7 and 54.5 %), relative water content (12.5 and 24.9 %) and superoxide dismutase (23.0 and 35.7 %) activity was observed. This was ascribed to the alleviation of membrane damage by reduced melondialdehyde content (18.9 and 21.4 %) and electrolyte leakage (21.9 and 26.7 %) under irrigated and drought regimes. However, higher doses of nanosilica caused slight reduction in plant growth and antioxidant activity. We conclude that, foliar spraying of nanosilica synthesized from rice husk at a concentration of 0.10 % for irrigated and 0.15 % for hybrid maize exposed to drought stress has shown a positive effect on plant growth and stress mitigation. Nanosilica synthesised from rice husk is economical, environmentally feasible and efficiently boosts plant growth and stress tolerance. Further, to confirm the role of rice husk derived nanosilica in plant stress tolerance, the comprehensive molecular mechanisms underpinning the stress mitigation has to be studied in detail.