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Abstract Salinity stress significantly hinders plant growth by disrupting osmotic balance and inhibiting nutrient uptake, leading to reduced biomass and stunted development. Using saponin (SAP) and boron (B) can effectively overcome this issue. Boron decreases salinity stress by stabilizing cell walls and membranes, regulating ion balance, activating antioxidant enzymes, and enhancing water uptake. SAP are bioactive compounds that have the potential to alleviate salinity stress by improving nutrient uptake, modulating plant hormone levels, promoting root growth, and stimulating antioxidant activity. That’s why the current study was planned to use a combination of SAP and boron as amendments to mitigate salinity stress in sweet potatoes. Four levels of SAP (0%, 0.1%, 0.15%, and 0.20%) and B (control, 5, 10, and 20 mg/L B) were applied in 4 replications following a completely randomized design. Results illustrated that 0.15% SAP with 20 mg/L B caused significant enhancement in sweet potato vine length (13.12%), vine weight (12.86%), root weight (8.31%), over control under salinity stress. A significant improvement in sweet potato chlorophyll a (9.84%), chlorophyll b (20.20%), total chlorophyll (13.94%), photosynthetic rate (17.69%), transpiration rate (16.03%), and stomatal conductance (17.59%) contrast to control under salinity stress prove the effectiveness of 0.15% SAP + 20 mg/L B treatment. In conclusion, 0.15% SAP + 20 mg/L B is recommended to mitigate salinity stress in sweet potatoes.

Abstract Chromium (Cr) stress significantly hinders crop production by disrupting nutrient uptake, impairing plant growth, and contaminating soil, posing a substantial threat to agricultural sustainability. The use of deashed biochar (DAB) and strigolactone can be an effective solution to mitigate this issue. Deashed biochar enhances crop production by improving soil structure, water retention, and nutrient availability while mitigating the bioavailability of toxic substances. Strigolactone boosts plant growth by stimulating root growth, branching, shoot formation, and overall plant physiology. Nevertheless, the scientific rationale behind their collective use as an amendment to counter Cr stress remains to be substantiated. Therefore, in this study, a blend of DAB and strigolactone was employed as additives in radish cultivation, both in the absence of Cr stress and under the influence of 200Cr stress. Four treatments, i.e., 0, 20µM Strigolactone, DAB, and 20µM Strigolactone + DAB, were applied in four replications following a completely randomized design. Results demonstrate that 20µM Strigolactone + DAB produced significant improvement in radish shoot length (27.29%), root length (45.60%), plant fresh weight (33.25%), and plant dry weight (78.91%), compared to the control under Cr stress. Significant enrichment in radish chlorophyll a (20.41%), chlorophyll b (58.53%), and total chlorophyll (31.54%) over the control under Cr stress, prove the efficacy of 20µM Strigolactone + DAB treatment. In conclusion, 20µM Strigolactone + DAB is the recommended amendment for mitigating Cr stress in radish. Farmers should consider using Strigolactone + DAB amendments to combat Cr stress and enhance radish growth, contributing to a more resilient agricultural ecosystem.

Abstract Soil salinity, the second most prominent cause of land degradation after soil erosion, has posed a persistent challenge to agriculture. Currently, approximately 1 billion hectares of Earth's land surface, equivalent to 7%, are affected by salinity. While biochar has proven effective in mitigating salinity stress, the specific role of deashed biochar in salinity mitigation has not been thoroughly explored. Therefore, this study was conducted to investigate the impact of four levels of deashed biochar (0%, 0.4%, 0.8%, and 1.2%) on the growth and physiological attributes of Fenugreek under both non-saline conditions (2.54 dS/m EC) and salinity stress conditions (5.46 dS/m EC). The results revealed a notable enhancement in various parameters under salinity stress. Compared to the control, the application of 1.20% deashed biochar led to a significant increase in shoot fresh weight (30.82%), root fresh weight (13.06%), shoot dry weight (17.43%), root dry weight (33.44%), shoot length (23.09%), and root length (52.39%) under salinity stress. Furthermore, improvements in internal CO2 concentration (9.91%), stomatal conductance (15.49%), photosynthetic rate (25.50%), and transpiration rate (10.46%) were observed, validating the efficacy of 1.20% deashed biochar in alleviating salinity stress. The study also demonstrated a significant decrease in the activities of oxidative stress markers such as peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), electrolyte leakage, and malondialdehyde (MDA). Simultaneously, there was an increase in the concentrations of essential nutrients, namely nitrogen (N), phosphorus (P), and potassium (K), in both shoot and root tissues. These findings collectively suggest that deashed biochar, particularly at a concentration of 1.20%, is recommended for achieving enhanced crop production under conditions of salinity stress.

Drought stress is one of the major abiotic factors that cause a significant decline in the crop's productivity. It can disturb photosynthesis by inducing oxidative stress by producing reactive oxygen species. Recently, the use of quantum has gained the attention of scientists due to its potential positive impacts on plants under stress conditions. That's why a current study was conducted to explore the impact of Zn-quantum dot biochar (QDB) on rapeseed growth under drought stress. There were four levels of QDB, i.e., control (no QDB), 0.2 %, 0.4 %, and 0.8 %, applied on a w/w basis in soil under normal irrigation and drought stress. Results showed that 0.8 %QDB performed significantly better in improving seedling's emergence, plant height, number of branches/plants, number of pods/plants, pod length, seed weight/plant, 1000 seeds weight, and total biomass of rapeseed under normal irrigation and drought stress. At 0.2 %, 0.4 %, and 0.8 % QDB levels, the photosynthetic rate was 9.19 %, 11.78 %, and 13.46 % higher than the control under drought stress. Compared to the control, the transpiration rate increased by 61.40 % with 0.2 % QDB, 123.46 % with 0.4 % QDB, and 199.71 % with 0.8 % QDB. The percentage increase in stomatal conductance ranged from 44 % for 0.2 % QDB to 129 % for 0.8 % QDB under drought stress. In conclusion, 0.8 %QDB can potentially reduce drought stress and improve the leaf water contents and nutrient uptake in rapeseed.

Abstract Salinity stress is one of the major hurdles in agriculture which adversely affects crop production. It can cause osmotic imbalance, ion toxicity that disrupts essential nutrient balance, impaired nutrient uptake, stunted growth, increased oxidative stress, altered metabolism, and diminished crop yield and quality. However, foliar application of osmoprotectant is becoming popular to resolve this issue in crops. These osmoprotectants regulate the cellular osmotic balance and protect plants from the detrimental effects of high salt concentrations. Furthermore, the role of arbuscular mycorrhizae (AMF) is also established in this regard. These AMF effectively reduce the salinity negative effects by improving the essential nutrient balance via the promotion of root growth. That’s why keeping in mind the effectiveness of osmoprotectants current study was conducted on cotton. Total of six levels of γ-Aminobutyric acid (GABA = 0 mM, 0. 5 mM, and 1 mM) and ectoine (ECT = 0 mM, 0.25 mM, and 0.5 mM) were applied as treatments in 3 replications. Results showed that 0.5 mM γ-Aminobutyric acid and ectoine performed significantly best for the improvement in cotton growth attributes. It also caused significant enhancement in K and Ca contents of the leaf, stem, bur, and seeds compared to the control. Furthermore, 0.5 mM γ-Aminobutyric acid and ectoine also caused a significant decline in Cl and Na contents of leaf, stem, bur, and seeds of cotton compared to control under salinity stress. A significant enhancement in chlorophyll contents, gas exchange attributes, and decline in electrolyte leakage validated the effectiveness of 0.5 mM γ-Aminobutyric acid and ectoine over control. In conclusion, 0.5 mM γ-Aminobutyric acid and ectoine have the potential to mitigate the salinity stress in cotton.

Abstract Lead (Pb) toxicity is a significant environmental issue, especially in areas with a past of industrial activities and mining. The existence of Pb in the soil can have negative impacts on plant growth and development, and it can also pose a risk to human health through the food chain. Acidified carbon has shown promise as an effective management technology for mitigating Pb toxicity. This study provides important insights into the potential of acidified biochar as a low-cost and eco-friendly method for managing Pb-contaminated soils. The current study explores the effectiveness of acidified biochar (AB) in alleviating Pb stress in mint. The study involved two levels of Pb (0 = control and 200 mg/kg Pb) and four levels of AB as treatments (0, 0.45, 0.90, and 1.20%). Results indicate that 1.20% AB was the most effective treatment, significantly decreasing root and shoot Pb concentration while enhancing shoot and root fresh and dry weight, shoot and root length, and shoot and root N, P, and K concentration. Moreover, a significant decrease in MDA (0.45AB, 0.90AB, and 1.20AB caused a decline in MDA content by 14.3%, 27.8%, and 40.2%, respectively) and an increase in ascorbic acid (0.45AB, 0.90AB, and 1.20AB led to an increase in ascorbic acid content of 1.9%, 24.8%, and 28.4%, respectively) validated the effectiveness of 1.20% AB compared to the control. Adding 0.45AB, 0.90AB, and 1.20AB led to an increase in soluble sugar content of 15.6%, 27.5%, and 32.1%, respectively, compared to the treatment without AB. Further investigations at the field level are suggested to confirm the efficacy of 1.20% AB as the best treatment against Pb toxicity in saline soil conditions.

Drought stress is one of the serious threats to crop production. It causes significant deterioration of crop growth and yield by inducing oxidative stress. The biochar and arbuscular mycorrhizae fungi (AMF) can be an effective technique to overcome drought stress. Activated carbon biochar (BC) has the potential to improve soil water holding capacity while AMF inoculation can increase root surface area for better uptake of water. However, their combined application as an amendment against drought still needs scientific justification. That's why the current study was conducted using a combination of AMF and BC on spinach under no drought stress and drought stress. The treatments included i.e., 0, 0.25%, and 0.50%AMF-BC. The experiment was replicated thre times using completely randomized design (CRD). Results showed that 0.5%AMF-BC increase spinach shoot fresh weight (20.34%), shoot dry weight (21.23%), shoot length (3.37%), root fresh weight (16.10%), root dry weight (14.51%), and root length (38.03%) over control under drought stress. The 0.50%AMF-BC increased chlorophyll a (15.33%), chlorophyll b (30.17%), total chlorophyll (18.85%), photosynthetic rate (35.59%), transpiration rate (26.53%), stomatal conductance (13.97%) and internal CO2 concentration (37.15%) compared to control under drought stress. The improvement in N, P, and K concentration in root and shoot verified the efficacious functioning of 0.50%AMF-BC compared to control under drought stress. In conclusion, 0.50%AMF-BC is recommended for the mitigation of drought stress in spinach.

The use of inorganic fertilizers has become increasingly necessary due to the depletion of soil fertility. Inadequate nutrient levels in both plants and soil can be remedied with the application of fertilizers. However, to achieve optimal results, it is recommended to supplement inorganic fertilizers with organic alternatives such as biochar. Despite its benefits, the high pH of activated carbon presents a significant challenge to its use in alkaline soil. Recent studies have shown that acidified carbon can be used instead of alkaline activated carbon. Moreover, the use of biofertilizers is crucial for maintaining soil quality. The purpose of the current study was to investigate the effects of using biofertilizers, inorganic nitrogen fertilizer, and acidified carbon fertilizer in combination on fenugreek growth and chlorophyll concentrations. A pot experiment was conducted using calcium ammonium nitrate (CAN) and three levels of acidified carbon (BC) at 0, 0.75, and 1.50%, with and without the addition of biofertilizer (BF). The results revealed that 1.50CANBC + BF was the most effective supplement for improving soil characteristics such as pH, EC, and overall organic matter. The application of 0.75CANBC + BF was found to be a successful treatment for promoting fenugreek growth and enhancing nitrogen absorption. To achieve better fenugreek quality by reducing electrolyte leakage and MDA, and increasing chlorophyll levels, gardeners are advised to use 1.50CANBC + BF. However, to establish 1.50CANBC + BF as the optimal method for fenugreek growth in poor fertility and high pH soils, further experimental studies in various agro-climatic conditions are necessary.

Abstract An important source of the destructive greenhouse gas, nitrous oxide (N2O) comes from the use of ammonium based nitrogen (N) fertilizers that release N2O in the incomplete conversion (nitrification) of NH4 + to NO3ˉ1. Biochar has been shown to decrease nitrification rates and N2O emission. However, there is little information from semi-arid environments such as in Pakistan where conditions favor N2O emissions. Therefore, the object was to conduct field experiment to determine the impact of biochar rates in the presence or absence of urea amended soils on yield-scaled N2O emissions, and wheat yield and N use efficiency (NUE). The experiment on wheat (Triticum aestivum L.), had a randomized complete block design with four replications and the treatments: control, sole urea (150 kg N ha−1), 5 Mg biochar ha−1 (B5), 10 Mg biochar ha−1 (B10), urea + B5 or urea + B10. In urea amended soils with B5 or B10 treatments, biochar reduced total N2O emissions by 27 and 35%, respectively, over the sole urea treatment. Urea + B5 or + B10 treatments had 34 and 46% lower levels, respectively, of yield scaled N2O over the sole urea treatment. The B5 and B10 treatments had 24–38%, 9–13%, 12–27% and 35–43%, respectively greater wheat above-ground biomass, grain yield, total N uptake, and NUE, over sole urea. The biochar treatments increased the retention of NH4 + which likely was an important mechanism for reducing N2O by limiting nitrification. These results indicate that amending soils with biochar has potential to mitigate N2O emissions in a semi-arid and at the same time increase wheat productivity.

Fourier transform infrared spectroscopy (FTIR) spectroscopy detects functional groups such as vibrational bands like N-H, O-H, C-H, C = O (ester, amine, ketone, aldehyde), C = C, C = N (vibrational modes of a tetrapyrrole ring) and simply C = N. The FTIR of these bands is fundamental to the investigation of the effect of biochar (BC) treatment on structural changes in the chlorophyll molecules of both plants that were tested. For this, dried leaf of Spinacia oleracia (spinach) and Trigonella corniculata (fenugreek) were selected for FTIR spectral study of chlorophyll associated functional groups. The study's primary goal was to investigate the silent features of infrared (IR) spectra of dried leave samples. The data obtained from the current study also shows that leaf chlorophyll can mask or suppress other molecules' FITR bands, including proteins. In addition, the C = O bands with Mg and the C9 ketonic group of chlorophyll are observed as peaks at1600 (0%BC), 1650 (3%BC) and 1640, or near to1700 (5%BC) in spinach samples. In fenugreek, additional effects are observed in the FTIR spectra of chlorophyll at the major groups of C = C, C = O and C9 of the ketonic groups, and the vibrational bands are more evident at C-H and N-H of the tetrapyrrole ring. It is concluded that C-N bands are more visible in 5% BC treated spinach and fenugreek than in all other treatments. These types of spectra are useful in detecting changes or visibility of functional groups, which are very helpful in supporting biochemical data such as an increase in protein can be detected by more visibility of C-N bands in FTIR spectra.

Mango fruit quality plays a significant role in fruit storage. It also directly affects the economic value of fruit in the national and international markets. However, deterioration of soil health due to low organic matter is a major hurdle for mango growers. Scientists suggest incorporation of organic matter. However, high temperature and low precipitation lead to oxidation of organic residues in soil. On the other hand, biochar is gaining the attention of growers due to its resistance against decomposition. It can improve soil physicochemical attributes. Limited literature is available regarding biochar effects on the quality attributes of mango. Therefore, the current study was planned to investigate the effects of acidified biochar on mango quality and yield attributes in alkaline soil. Five levels of biochar, i.e., 0, 5, 10, 20 and 40 Mg/ha, were applied in a randomized complete block design (RCBD). Results showed that 20 and 40 Mg/ha acidified biochar significantly enhanced fruit retention, sugar contents, ash contents and TSS of mango compared to control. A significant increase in mango fruit weight and yield per plant validated the efficacious role of 40 Mg/ha acidified biochar over control. Furthermore, the maximum significant decrease in fruit juice acidity signified the imperative functioning of 40 Mg/ha acidified biochar in alkaline soil. In conclusion, 40 Mg/ha acidified biochar application can improve mango quality and yield attributes in alkaline soil. More investigations on different soil types, climatic zones and mango varieties are recommended to declare 40 Mg/ha acidified biochar as the best treatment for improvement in the quality and yield of mango fruit in alkaline soils.

Pea (Pisum sativum L.) leaf chlorophyll and pigments syntheses are retarded under nutritional stress. Biochar has the potential to regulate soil nutrient supplies and optimize plant nutrient uptakes. We examine the role of Pongamia pinnata L. waste leaf biochar (PLB) in improving vegetative growth and leaf chlorophyll and accessory pigments of pea exposed to nutritional stress. Three PLB application rates (0, 1, and 2%) crossed with half (HF), and full NPK fertilizer (FF) recommended doses were applied to sandy soil field-pots (arranged in a completely randomized design). There were significant or maximum increases in plant vegetative or physiological traits, including the fresh or dry, above- and below-ground biomass weights, and photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and anthocyanin) in response to a 2%PLB + FF application (p = 0.002). Trait values also responded to 2%PLB + HF, which signified the nutrient regulatory character of PLB (p = 0.038). The PLB-driven reduction in nutritional stress resulted in diminished lycopene (antioxidant) content (p = 0.041). Therefore, we suggest that the soil application of 2%PLB + FF has the greatest impact on pea vegetative growth and leaf chlorophyll, carotenoids, anthocyanin, and lycopene contents in Pisum sativum L. Further research is recommended to investigate the relationship of PLB with soil nutrient availabilities and plant nutrient concentrations.

Cadmium (Cd) has no defined biological role and may enter the food chain from polluted soils. Biochar has been proposed as an organic amendment to minimize the toxic effects of Cd for plants grown on contaminated soils. In this study, biometric and biochemical attributes of fenugreek (Trigonella corniculata) grown on artificially cadmium (Cd) contaminated soil (0, 25, 50, 75 and 100 mg Cd/kg soil) at three levels of cotton-sticks derived biochar (CSB; 0, 3 and 5 %) were studied. Data show significant decline in the growth, photosynthetic pigments (chlorophyll a, b and total, carotenoids, anthocyanin and lycopene), and physiological attributes (sub-stomatal CO2 concentrations, photosynthetic and transpiration rate) in the presence of high Cd concentrations (50 and 100 mg Cd/kg soil). However, the decline was reduced in the presence of CSB. A steady amplification in lipid peroxidation (assessed via Malondialdihyde (MDA)) and ascorbic-acid assembly was noted with increasing Cd. The concentration of Cd in the root and shoot also decreased with increasing CSB application rates from 3 % - 5 %. Overall, the greater production of protein, amino acids and sugar contents in response to higher application rates of CSB seems to be due to alleviation in Cd toxicity. Thus, cotton-sticks can be safely utilized in the form of biochar as amendment with additional benefit of reducing Cd bioavailability and toxicity to crop plants.