Global climate change accelerates the challenges of agricultural drought spells, which are alarming for food security and can trigger food scarcity. Therefore, improving soil-water retention capability and crop drought resilience is becoming more important for sustainable agriculture. This study investigates the individual and combined effects of biochar and potassium on soil water retention, crop drought resilience, and related physio-biochemical mechanisms over a 50-day growth period in potted plants. Pine needle biochar (350 g/10 Kg of soil) was used during the soil preparation stage while potassium sulfate (100 mg/L) was applied as a foliar spray at the development (10 days) and vegetative stages (45 days) under three drought stress conditions: control (100% FC), mild (75% FC) and severe (40% FC). The results revealed that the combined application of biochar and potassium significantly increased morphological, physiological, and biochemical attributes of maize plants under drought stress, improving shoot fresh weight by 11%, 6%, and 5%, root fresh weight by 19%, 19%, and 23%, shoot length by 17%, 16%, and 19%, and root length by 21%, 30%, and 29% under control, mild, and severe drought stress conditions, respectively. Similarly, relative water contents (RWC) increased by 12%, 16%, and 20%, water potential (Psi) increased by 26%, 22%, and 24%, osmotic potential (Psi s) increased by 100%, 59%, and 30%, and turgor potential (Psi p) increased by 28%, 35%, and 51% under combined treatment compared to control, mild, and severe drought stress. Additionally, biochar application with potassium foliar spray also improved membrane stability and integrity, cell wall loosening, membrane lipid peroxidation, and protein denaturing by decreasing electrolytic leakage by 35%, 28%, and 43%, proline by 30%, 27%, and 22%, hydrogen peroxidase by 47%, 45%, and 41%, and malondialdehyde contents by 24%, 20%, and 28% through activation of enzymatic (CAT, POD, SOD) and non-enzymatic (TSS, AsA, GSH) antioxidants. Furthermore, nutrient uptake was enhanced, with N increasing by 47%, 19%, and 45%, P by 64%, 82%, and 52%, and K by 24%, 42%, and 35% in shoots compared to normal, mild, and severe drought stress. These improvements mitigated cell dehydration, reduced transpiration inefficiency and delayed senescence, and ultimately supporting plant growth under drought stress. In conclusion, integrating biochar with potassium application effectively improves soil-water retention, alleviates oxidative stress and enhances drought tolerance in maize plants. This strategy can play a crucial role in sustainable agriculture by mitigating the adverse effects of drought stress and improving food security in drought-prone regions.

Salinity stress (NaCl) and heavy metals contamination (CdCl2) are the serious environmental constraints for decreased crop production worldwide. However, the interaction between NaCl and CdCl2 regarding sodium (Na), cadmium (Cd), and chloride (Cl) accumulation in plants has not been completely established. Therefore, the interactive effects of NaCl andCdCl2 on plant growth, Na, Cd, and Cl accumulation in plants, and wheat yield were evaluated. Wheat seeds were cultivated in clay loam soil under greenhouse conditions. After two weeks of sowing, plants were subjected to NaCl at the rate of 0, 50, and 100 mM either alone or in combination with CdCl2: 0, 1, and 2 mM, respectively. The results revealed that increasing NaCl and CdCl2 levels reduced Na and Cd concentrations, whereas enhanced Cl concentrations. Furthermore, moderate levels of CdCl2 and NaCl stresses enhanced the antioxidative enzymatic activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in addition to proline accumulation in wheat leaves. By contrast, 100 mM NaCl in combination with 2 mM CdCl2 enhanced H2O2 accumulation by 105%, which thus decreased the membrane stability index (MSI) by 49% and wheat yield by 27% as compared to 2 mM CdCl2. The reduced Cd toxicity by NaCl or Na accumulation in plant tissues by CdCl2 involved competition between Na and Cd at binding sites, however, enhanced Cl phytotoxicity in plants resulted in the overproduction of H2O2 that was not quenched by antioxidative enzymes, thereby decreased MSI and wheat yield.

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.

Background Oxidative stress mediated by reactive oxygen species (ROS) is a common denominator in arsenic toxicity. Arsenic stress in soil affects the water absorption, decrease stomatal conductance, reduction in osmotic, and leaf water potential, which restrict water uptake and osmotic stress in plants. Arsenic-induced osmotic stress triggers the overproduction of ROS, which causes a number of germination, physiological, biochemical, and antioxidant alterations. Antioxidants with potential to reduce ROS levels ameliorate the arsenic-induced lesions. Plant growth promoting rhizobacteria (PGPR) increase the total soluble sugars and proline, which scavenging OH radicals thereby prevent the oxidative damages cause by ROS. The main objective of this study was to evaluate the potential role of Arsenic resistant PGPR in growth of maize by mitigating arsenic stress. Methodology Arsenic tolerant PGPR strain MD3 (Pseudochrobactrum asaccharolyticum) was used to dismiss the 'As' induced oxidative stress in maize grown at concentrations of 50 and 100 mg/kg. Previously isolated arsenic tolerant bacterial strain MD3 Pseudochrobactrum asaccharolyticum was used for this experiment. Further, growth promoting potential of MD3 was done by germination and physio-biochemical analysis of maize seeds. Experimental units were arranged in Completely Randomized Design (CRD). A total of 6 sets of treatments viz., control, arsenic treated (50 & 100 mg/kg), bacterial inoculated (MD3), and arsenic stress plus bacterial inoculated with three replicates were used for Petri plates and pot experiments. After treating with this MD3 strain, seeds of corn were grown in pots filled with or without 50 mg/kg and 100 mg/kg sodium arsenate. Results The plants under arsenic stress (100 mg/kg) decreased the osmotic potential (0.8 MPa) as compared to control indicated the osmotic stress, which caused the reduction in growth, physiological parameters, proline accumulation, alteration in antioxidant enzymes (Superoxide dismutase-SOD, catalase-CAT, peroxidase-POD), increased MDA content, and H2O2 in maize plants. As-tolerant Pseudochrobactrum asaccharolyticum improved the plant growth by reducing the oxidation stress and antioxidant enzymes by proline accumulation. PCA analysis revealed that all six treatments scattered differently across the PC1 and PC2, having 85.51% and 9.72% data variance, respectively. This indicating the efficiency of As-tolerant strains. The heatmap supported the As-tolerant strains were positively correlated with growth parameters and physiological activities of the maize plants. Conclusion This study concluded that Pseudochrobactrum asaccharolyticum reduced the 'As' toxicity in maize plant through the augmentation of the antioxidant defense system. Thus, MD3 (Pseudochrobactrum asaccharolyticum) strain can be considered as bio-fertilizer.

Globally from abiotic stresses, salt stress is the major stress that limits crop production. One of them is wheat that has been utilized by more than 1/3 of the world population as staple food due to its nutritive value. Biochar is an activated carbon that can ameliorate the negative impacts on plants under saline conditions. The present study was conducted to examine the ameliorative impact of Biochar application to Triticum aestivum L. plant grown under salinity stress and evaluated on the basis of various growth, yield, physiological, biochemical attributes. Preliminary experiment was done to select the Triticum aestivum L. varieties with 90% germination rate for further experiment. The selected varieties, FSD08 and PUNJAB-11 of wheat were treated with two levels of sodium chloride (0 mM and 120 mM). Two varieties of wheat included FSD08 and PUNJAB-11 were treated with two levels of sodium chloride (0 mM and 120 mM). To address the impact of salt stress two levels of biochar 0% and 5% was used as exogenous application. A three way completely randomized experimentation was done in 24 pots of two wheat varieties with three replicates. The results demonstrated that salt stress affected growth, physiological attributes, yield and inorganic mineral ions (Ca2+ and K+) in roots and shoots parameters of wheat negatively while biochar overall improved the performance of plant. SOD, CAT, APX and POD activities enhanced during salt stress as the plant self-defense mechanism against salinity to minimize the damaging effect. Salt stress also significantly increased the membrane permeability, and levels of H2O2, MDA, Cl and Na ions. Biochar treatment nullified negative impacts of NaCl and improved the plant growth and yield significantly. Hence, biochar amendment can be suggested as suitable supplement for sustainable crop production under salinization.