This study aimed to evaluate the synergistic effects of zinc sulfate and Pseudomonas spp. in terms of mitigating drought stress in maize (Zea mays L.) by analyzing physiological, biochemical, and morphological responses under field conditions. A two-year (2018-2019) field experiment investigated two irrigation levels (optimal and moderate stress) and twelve treatment combinations of zinc sulfate application methods (without fertilizer, soil, foliar, and seed priming) with zinc-solubilizing bacteria (no bacteria, Pseudomonas fluorescens, and Pseudomonas aeruginosa). Drought stress significantly reduced chlorophyll content, increased oxidative damage, and impaired membrane stability, leading to a 42.4% increase in electrolyte leakage and a 10.9% reduction in leaf area index. However, the combined application of zinc sulfate and P. fluorescens, and P. aeruginosa mitigated these effects, with seed priming showing the most significant improvements. Specifically, seed priming with zinc sulfate and P. fluorescens increased catalase activity by 76% under non-stress conditions and 24% under drought stress. Principal component analysis revealed that treatments combining zinc sulfate and P. fluorescens, and P. aeruginosa were strongly associated with improved chlorophyll content, carotenoid content, and grain yield while also enhancing osmotic adjustment and antioxidant enzyme activity. These findings highlight the potential of the use of zinc sulfate and P. fluorescens as well as P. aeruginosa as sustainable strategies for enhancing maize drought tolerance, mainly through seed priming and soil application methods.

Water deficit has a negative effect on the physiological aspects of plants, such as stomatal closure and consequent decline in photosynthetic carbon assimilation. Numerous water deficit mitigation strategies have been investigated, such as the use of bioregulators to minimize the damage caused. This study aimed at assessing the effects of brassinosteroids on the physiological aspects of a & ccedil;a & iacute; seedlings in inducing drought tolerance. The experiment was conducted using two water conditions (well-watered and water-deficit plants) and three brassinosteroid concentrations (0, 0.05 and 0.10 mu M of 24-epibrassinolide-EBL), with six repetitions. At 120 days, seedlings were transplanted to pots and watered, leaving the soil near field capacity for 56 days. Next, a group of plants were well-watered, and another submitted to water deficit for 18 days. Water deficit reduced gas exchange and photosynthetic efficiency with a lower decrease at EBL concentrations of 0.05 and 0.10 mu M, while larger declines were observed in plants without EBL. Relative water content and leaf succulence were maintained in water-deficit plants, while proline content rose, mainly with 0.10 mu M of EBL. Applying EBL also improved water use efficiency and maintained the leaf chlorophyll and stem dry matter of stressed plants. It was concluded that leaf brassinosteroid application alleviate of harmful effects of water deficit in young a & ccedil;a & iacute; plants, promoting proline accumulation, which increases water use efficiency, and maintaining photosynthetic pigments and water status, contributing to improving drought tolerance in a & ccedil;a & iacute;.

Soil salinization has emerged as a major factor negatively affecting soil quality and plant productivity. Proline, functioning as an osmotic regulator, has been proposed as an effective strategy for enhancing plant tolerance to salt stress. This study aimed to investigate the effects of exogenous proline on salt tolerance in soybeans. A hydroponic experiment was conducted with different salt treatments (without NaCl, -NaCl; with 100 mM NaCl, +NaCl) and with or without 150 mM proline (+Pro, -Pro). The results showed that proline application alleviated salt stress-induced reductions in plant growth, photosynthetic parameters, and chlorophyll content while aiding recovery from leaf chlorosis. Proline treatment improved ion homeostasis by reducing Na+ levels and increasing K+ and Ca2+ contents in the leaves. Salt stress increased malondialdehyde (MDA) and reactive oxygen species (ROS) levels, along with leaf peroxidase (POD) and catalase (CAT) activities, while decreasing superoxide dismutase (SOD) activity. Moreover, salt stress obviously enhanced proline accumulation, accompanied by increases in glutamate (Glu), glutamate-1-semialdehyde (GSA), and pyrroline-5-carboxylate (P5C) content, as well as the activities of pyrroline-5-carboxylate synthase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) in the glutamate pathway, while reducing proline dehydrogenase (ProDH) activity. Exogenous proline treatment further elevated proline content and increased key substances and enzyme activities in both the glutamate (Glu and P5C content, P5CS and P5CR activity) and ornithine (Orn content and OAT activity) pathways while also reducing ProDH activity. Collectively, our results revealed that exogenous proline contributed to an attenuation of salt stress in soybeans by regulating both the glutamate and ornithine pathways to stimulate endogenous proline accumulation, mediate Na+/K+ homeostasis, and inhibit oxidative damage.

Introduction The heavy metal elements cadmium (Cd) and zinc (Zn) often coexist in nature, making the environmental media more prone to compound pollution. However, research on the toxic effect of the Cd-Zn combination is still lacking, and the underlying toxic mechanisms remain unclear.Methods Therefore, in this experiment, we established four treatment groups with different ratios of Cd-Zn compound stress for the broad bean, Vicia faba L., and aphids, Megoura crassicauda, to explore the growth and physiological adaptation mechanisms under different levels of mixed heavy metal stress.Results By measuring the germination rate, seedling height, and chlorophyll content of broad beans, we found that Cd-Zn-mixed stress has a synergistic inhibitory effect on the growth and development of broad beans. Cd and Zn can be transferred through the food chain, while broad beans can resist complex stress by regulating the content of total soluble sugars and photosynthetic pigments in the body, as well as accumulating proline. In addition, in the first generation of adult aphids, treatment with Cd (12.5 mg/kg) + Zn (100 mg/kg) significantly affected the expression of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) genes and influenced the carbohydrate content and trehalase activity in the aphids.Discussion The number of offspring produced by the second-generation aphids was significantly reduced under mixed heavy metal treatment, but it was not caused by changes in the vitellogenin (Vg) content. These related results provide new avenues for further exploration of plant responses to mixed heavy metal stress, pest control, and management of heavy metal pollution.

Lead (Pb) contamination in rhizosphere soil inhibits seed germination and impairs ATP generation, causes lipid peroxidation, damages DNA molecules, and increases reactive oxygen species (ROS) formation, leading to decreased chlorophyll synthesis and plant growth. Using PGPR in combination with organic amendments has emerged as an eco-friendly and sustainable biological approach to reducing heavy metal toxicity in vegetables. In view, lead-tolerant Bacillus sp. strain N18 was evaluated along with compost to ameliorate lead toxicity in tomatoes under lead-contaminated soil conditions. The test soil was spiked with different concentrations of Pb (0, 400 and 600 mg kg- 1) and placed for 72 h for equilibrium before filling the plastic jars. Five 20-day-old tomato plants were transplanted in each jar and harvested after 40 days of transplantation. Results showed that plant height and root length were significantly improved by 11 and 49% over the control, while SPAD value was enhanced by 31% due to the combined use of Bacillus sp. strain N18 and compost under 600 mg kg- 1 of lead. The lead in root and shoot decreased by 6 and 13% compared with the un-inoculated control under 600 mg kg- 1 of Pb. The combination of Bacillus sp. strain N18 and compost also improved the enzymatic and non-enzymatic antioxidant systems by decreasing the proline contents, superoxide dismutase (SOD) activity, peroxidase (POD) activity, catalase (CAT) activity and peroxidase (POX) activity. It is concluded that the combined use of lead-tolerant Bacillus sp. strain N18 and compost effectively ameliorated the lead toxicity in tomatoes grown under Pb-contaminated soil conditions. The integrated use of Bacillus sp. N18 and compost showed the potential for improving tomato growth and physiology under Pb-contaminated soils and decreasing the Pd uptake in tomato plants by stabilizing it in the root zone. This approach can be explored as a good strategy for growing vegetables, especially tomatoes, in Pb-contaminated peri-urban areas.

Purpose: Biochar is a carbon rich material that showed positive outcomes on plant growth and productivity enduring abiotic stresses. The objective of the present investigation is thus to determine the potential of biochar to mitigate the detrimental impacts of salinity in Lepidium sativum. Method: Salinity stress was induced by NaC1 at different concentrations ranging from 0 to 5000 mg/L. Biochar was applied in two concentrations: 0.5 and 1%. For biochar preparation, dry rice straw was heated at 400 OC at certain pyrolysis conditions. Results: The study established that salt medium significantly reduced seed germination and amylase activity, with the highest decrease of 63 and 50.6%, respectively, at 5000 mg/L. The relative permeability of the cell membrane was associated with substantial increases in lipid peroxidation and hydrogen peroxide. The free radicle scavengers' total phenolic, flavonoid, and proline levels were also induced. The use of prepared biochar at 0.5 and 1% reduced the damaging effects of salt stress by enhancing the activity of the alpha-amylase enzyme, resulting in a significant rise in germination (95% at 5000 mg/L by 0.5% of biochar). In contrast, the application of 0.5% biochar at 5000 mg/L significantly decreased MDA and hydrogen peroxide concentrations to 24.4 mg/g f wt and 1.39 mM/g d wt, respectively, compared to 48.21 and 1.77 in the control. Positive relationships between the multiple data revealed the largest augmentation of germination, dry weight, and antioxidant chemicals in stressed seedlings with 0.5% biochar. Biochar alleviated the hazardous effects of NaCl on L. sativum by decreasing free radicle formation and lipid peroxidation, thereby enhancing germination and early growth. Conclusion: The positive impact of biochar on salt stressed seedlings may underline its potential to have opposing NaCl consequences on development and sustain growth.

Abiotic constraints, such as salinity, significantly damage crop yields worldwide. Cotton, though moderately salttolerant, suffers from reduced growth and yield under saline-sodic soil conditions. Effective integrated mitigation strategies are crucial to address this challenge. Our study, conducted in Lodhran, Punjab, Pakistan, investigated six treatments using an integrated strategy such as gypsum, compost and exogenous proline combining effect in improving cotton productivity under salinity stress. We assessed plant growth, agronomic traits, physio-chemical parameters, cotton yield, and soil characteristics. Our experimental results showed that the combined application of amendments such as T5: gypsum + proline and T6: compost + proline gave better results as compared to individual treatments (T2, T3 & T4) over the control (T1). A significant improvement was observed in plant length and dry weights of shoot and root by 64 %, 81 % and 47 %, respectively under the effect of T5, also increased cotton yield up to 2 folds (888 kg) over control (324 kg ha-1 ). Likewise, significant improvement in the plant physio-chemical parameters was recorded such as high activities of antioxidant enzymes and the maximum accumulation of malondialdehyde (MDA) content by 60 -71 %, as well as reduction in the oxidative burst by 55 -65 % after the integrated treatments (T5 & T6) as compared to salt-stressed plants (control). Likewise, contents of nutrients are improved in plants viz., N: 70; P: 61 %; K: 33 % and Mg: 86 % under the positive effect of gypsum + proline over control. Results of soil analysis showed that the soil was moderately saline-sodic. Furthermore, soil analysis revealed that there was a significant improvement in NPK, S and Mg content in the soil after treated salt-stressed soil with gypsum and compost (T2, T3, T5 and T6) while a significant reduction was observed in Ca (17 %) and Na content (28 %), as well as EC (dSm- 1 ) was decreased by 38 % and SAR (mmol/ L)1/2 by 27 % under the effect of gypsum + proline over the control treatment. The outcomes of the current study reveal that the reclamation potential of gypsum and compost applied individually or together with exogenous proline improved plant growth, yield and plant defense system under salinity stress.

Plants exposed to adverse environmental conditions develop molecular mechanisms of adaptation and/or defense, the osmoprotectors, which function as compatible solutes and contribute to tolerance via prevention systems and protection against cellular damage caused by these abiotic stresses. This study aimed to identify and characterize the osmoprotectors proline and trehalose in cowpea plants cv. Carijo under controlled conditions of water-deficit and heat stress based on the IPCC scenario of 4.8 degrees C increase in temperature, evaluating their structure and function through computational methods, as well as gene expression by RT-qPCR. The experimental assays were carried out in growth chambers under controlled conditions with different levels of soil water availability, phenological phases and temperature regimes. From the in silico analyses, ten TPS genes and one P5CR gene were identified in Vigna unguiculata, and these were named according to their chromosomal location. The VuP5CR and VuTPS genes play roles in hormone pathway signaling and in the response to light and biotic and abiotic stresses. The genes P5CR (proline) and alpha TPS6 (trehalose) were induced with increased temperature and lower water availability in the vegetative phase of cowpeas. In addition, P5CR also showed induction with 50% water availability at high temperatures. In the pod filling phase, the P5CR and alpha TPS6 genes were repressed with water availability of 75%, while only the P5CR gene was induced when water availability was reduced to 25% under heat stress. P5CR and TPS6 genes were induced in cowpea cv. Carijo in response to associated abiotic stresses (water-deficit and high temperatures), which suggests their participation in the mechanisms of adaptation of the species in adverse environmental conditions.

Nanotechnology is a vital domain for improving growth, productivity, and abiotic stress resistance of horticultural crops. In this study, semi-spherical shaped biogenic AgNPs with size ranging between 21 nm and 48 nm were synthesized using rambutan fruit extract and characterized using SEM and TEM, and beneficial effects of AgNPs on salt-treated marigold (Calendula officinalis L. cv. Orange King) plants were evaluated. Plants were grown in pots filled with sandy loam soil until reaching up to six leaves and then irrigated with water containing 100 mM NaCl. After a week of salt stress, foliar spray treatments with AgNPs were performed three times every 20 days. Results showed that shoot and root dry weights and total chlorophyll content of salt-stressed plants decreased more than 35 % compared to non-stressed plants, but oxidative biomarkers including electrolyte leakage (EL) and concentrations of malondialdehyde (MDA) and hydrogen peroxide (H2O2) substantially increased. Foliar spraying of AgNPs decreased EL and proline contents, increased leaf chlorophyll and protein contents, and alleviated the growth inhibition of salt-stressed plants. The amelioration of salt stress was accompanied by changes in the activities of antioxidant enzymes (SOD, APX, CAT, POD, PPO, and PAL) and reduction of MDA and H2O2 concentrations. Floral secondary metabolites including carotenoids, total flavonoids, total phenols, as well DPPH improved in response to application of AgNPs. Our data suggest that AgNPs were able to alleviate negative effects of salt stress on marigold plants through its ability to produce enzymatic and nonenzymatic antioxidants. Thus, foliar application of AgNPs could be a viable solution to improve its growth and edible flowers production when grown in salt affected soils.

Methyl jasmonate (MeJA) is a phytohormone involved in plant defense against stress. However, its application as pretreatment in soybean seeds is limited. Here, we investigated whether seed pretreatment with MeJA mitigated the negative effects of water restriction (WR) and mechanical wounding (MW) in soybean seedlings at the V1 vegetative stage. Seeds of Glycine max (Monsoy 6410 variety) were pretreated with water or 12.5 mu M MeJA for 14 h. The obtained seedlings were transferred to pots containing substrate (soil and sand) kept in a greenhouse and subjected to different growth conditions: control (no stress), WR (40% water retention), and MW. The experiment was conducted in a 2 x 3 factorial scheme (2 seed pretreatments x 3 growth conditions). The variables analyzed were ethylene levels, hydrogen peroxide, lipid peroxidation, antioxidant system enzymes, sugars, amino acids, proteins, proline, and growth (root and shoot length). WR negatively affected seedling growth, regardless of seed pretreatment, but proline levels increased with MeJA application. In seedlings subjected to MW, MeJA increased ethylene release, which was related to reduced damage. It suggests that pretreatment of soybean seeds with MeJA is a promising tool to mitigate the deleterious effects of biotic and abiotic stresses during seedling establishment, inducing distinct tolerance strategies.