Introduction

The excessive application of glyphosate and continuous use of the broad-spectrum herbicide negatively affect plant growth and damage soil health in agricultural systems. Plants ingest glyphosate primarily by blocking 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), a vital catalyst in the shikimate pathway to produce aromatic amino acids. The inhibitory effect causes disruption of protein synthesis, a decrease in chlorophyll, and deterioration of photosynthesis, resulting in slow plant growth and a change in leaf coloration, as well as decreased plant mass1,2,3,4,5,6,7 . The formation of excessive reactive oxygen species (ROS) under glyphosate stress triggers oxidative damage, which activates antioxidant defense by upregulating peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD)4. The application of glyphosate in soil causes three main detrimental effects, including modification of microbial communities, decreased beneficial microorganisms, and disturbances in nutrient cycles, particularly affecting nitrogen and phosphorus movements. The absorption process of essential micronutrients, including iron, manganese, and zinc, becomes restricted when glyphosate binds to these nutrients, making them difficult for plants to obtain. Glyphosate residues can create additional phytotoxicity because they remain in the soil, migrate to groundwater, and accumulate in plant tissues. This disruption collectively results in compromised plant health, reduced agricultural production, and lasting damage to soil fertility8.

Zeolite (ZL) is a naturally occurring aluminosilicate mineral with a porous structure and a strong cation exchange capacity, making it a superior amendment for enhancing soil quality and promoting plant growth9. It retains essential nutrients, including ammonium (NH₄⁺), potassium (K⁺), calcium (Ca2⁺), and magnesium (Mg2⁺), and prevents soil leaching, ensuring plants receive a consistent supply of nutrients10. Zeolite also improves soil structure, aeration, and water-holding capacity, which are crucial for root development and overall plant vigor, especially under drought or nutrient-deficient conditions11. The buffering capacity of zeolite changes soil pH and maintains optimal conditions for nutrient acquisition. Utilizing zeolite leads to increased plant biomass output, while also enhancing root growth and improving the physiological functioning of the plants12.

Biochar (BC) is a carbon-rich, porous material produced through the pyrolysis of organic biomass under limited oxygen conditions13. It is widely recognized for enhancing soil fertility, improving water retention, reducing greenhouse gas emissions, and immobilizing soil contaminants, making it a promising tool for sustainable agriculture14. Tea is a major agricultural product that grows in tropical and subtropical areas worldwide. The annual production of tea worldwide exceeded 5.98 million metric tons in 2017, resulting in significant waste generation from tea production15. The nutrient content of tea waste includes nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and polyphenols, which enhance soil quality and support plant development. Tea waste’s organic matter enhances microbial activity, soil structure, and nutrient availability16. Solving waste materials into biochar represents a sustainable method to minimize solid waste accumulation. The research evaluates how the transformation of tea waste into biochar helps manage waste while investigating its environmental benefits as a sustainable soil amendment for reducing stress and improving crop yield under glyphosate stress.

Glyphosate stress causes detrimental effects on maize plant growth because it disrupts the shikimic acid pathway through which plants synthesize aromatic amino acids17. The disruption in the shikimic acid pathway results in reduced protein production, stunted growth, chlorosis, and lower biomass accumulation18. Prolonged exposure to glyphosate stress causes damage to root development, blocking nutrient absorption and photosynthetic capacity, which results in reduced crop yield19. The current research investigates how tea waste biochar (TWBC) and ZL mitigate glyphosate stress and improve maize growth. This research addresses a critical knowledge gap by investigating the individual and synergistic effects of TWBC and ZL on maize performance under stress induced by glyphosate. The novelty of the study lies in demonstrating TWBC and ZL as an integrated management approach that not only mitigates the toxic effects of glyphosate but also improves maize resilience, nutrient uptake, and productivity.

Materials and methods

Experimental site

In 2024, a pot experiment was carried out at the Pesticide Quality Control Laboratory (PQCL) (30°09′17.3″N 71°26′35.0″E), situated in Multan, Punjab, Pakistan. To evaluate the soil’s physicochemical properties, soil samples were collected and then air-dried before being sieved through a 2-mm mesh. The soil characteristics were determined as follows (Table 1):

Table 1 Characteristics of experimental soil.
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Preparation and characterization of biochar

Initially, tea waste was collected from tea stalls in the local area (30°11′31.4″N 71°28′41.6″E). After sun drying, pyrolysis was performed at 525 ± 5 °C for 94 min. The BC characterization was conducted according to standard protocols for assessing its properties. The tea waste biochar exhibited a pH of 8.13 and electrical conductivity (EC) of 3.48 dS/m. The volatile matter content was 17.5% (%), ash content 21.2% (%), and fixed carbon 61.3% (%), indicating a stable and carbon-rich composition. The biochar had a Brunauer–Emmett–Teller (BET) surface area of 142 m2/g and a total pore volume of 0.27 cm3/g. The cation exchange capacity (CEC) was measured at 38.4 cmol/kg. Elemental analysis revealed 1.60% nitrogen, 0.10% phosphorus, 0.3% potassium, 0.6% calcium, 0.10% magnesium, 0.30% sulfur, 182 mg/kg iron, and 35 mg/kg zinc. Fourier-transform infrared spectroscopy (FTIR) analysis was conducted to examine the functional groups present in the biochar by using Thermo Scientific Nicolet 6700.

Zeolite

For the present study, a natural zeolite was obtained from the local mining resources market in Pakistan (Khyber Pakhtunkhwa). The characteristics include: CEC ~ 92.1 cmol kg⁻1, Si/Al ratio 3–5, water-holding capacity (30% by weight), porosity ~ 34%, bulk density 1.15 g/cm3, and specific gravity ~ 2.25 g/cm3.

Treatment plan and glyphosate contamination

The treatments included five levels of tea waste biochar (TWBC) (0%, 0.15%, 0.30%, 0.60%, and 1.20% TWBC), applied with two levels of zeolite (ZL) (0% and 5% ZL). Total number of treatments were 10 [T1 (control = 0%TWBC + 0%ZL), T2 (0.15%TWBC + 0%ZL), T3 (0.30%TWBC + 0%ZL), T4 (0.60%TWBC + 0%ZL), T5 (1.20%TWBC + 0%ZL), T6 (0%TWBC + 5%ZL), T7 (0.15%TWBC + 5%ZL), T8 (0.30%TWBC + 5%ZL), T9 (0.60%TWBC + 5%ZL) and T10 (1.20%TWBC + 5%ZL) applied following completely randomized design (CRD) with three replications. However, a 2.5 mg/L glyphosate concentration was maintained in the irrigation water to induce glyphosate stress20. The plants were irrigated with this water to maintain the 65% field capacity (FC) throughout the experiment.

Fertilizer

To address the maize nutritional requirements, 119 kg per acre of nitrogen (N), 69 kg per acre of phosphorus (P), and 50 kg per acre of potassium (K) were applied, utilizing urea as the nitrogen source and single superphosphate for phosphorus, at the recommended rates.

Irrigation

The irrigation of each pot is measured and adjusted using a moisture gauge (ADVANCED™; 4-in-1 Soil Meter; China). The researcher checked the soil moisture level daily to verify the desired threshold, which was 65% of the field capacity, as indicated by the instrument reading scale.

Collecting, sterilization, and sowing of seeds

The maize seeds used in this study were procured from a licensed seed vendor authorized by the Government of Punjab, Pakistan. Stringent quality control procedures were implemented to ensure seed viability, with damaged or weak seeds deliberately excluded during the selection process. An extensive surface sterilization process took place before sowing the selected seeds. The seeds required three ethanol rinses at 95% concentration following treatment with 5% sodium hypochlorite solution. The seeds received an additional three rinses of sterilized deionized water to remove any remaining sterilizing agents after their exposure to the 5% sodium hypochlorite solution. Each pot contains 5 kg of soil and initially received 10 seeds for sowing. The thinning procedure followed seed germination to maintain two seedlings per pot21.

Data collection

The data was collected 65 days after harvesting. After harvesting, the fresh and dry weights of the shoots and roots were measured using a digital balance. Samples were oven-dried for 72 h at 65 °C to calculate the dry weights of the shoots and roots.

Estimation of chlorophyll (SPAD)

SPAD (SPAD-502 Portable Chlorophyll Meter) was used to measure leaf chlorophyll content in the portable leaf chlorophyll meter.

Antioxidants

The activity of superoxide dismutase (SOD) was measured by assessing the inhibition of NBT decrease at a wavelength of 560 nm22. Peroxidase (POD) activity was measured at 420 nm with the standard protocol of23. By monitoring the decomposition of hydrogen peroxide (H2O2), catalase (CAT) activity was measured. The H2O2 decomposition was measured through the decrease in the absorbance at 240 nm24. Ascorbate peroxidase (APX) activity was measured through the ascorbate oxidation reaction in the presence of H2O2 at 290 nm using method25.

Gas exchange attributes

Data were collected on a clear, sunny day between 10:30 and 11:30 AM, coinciding with the optimal light intensity for photosynthetic activity26 using an infrared gas analyzer (CI-340 Photosynthesis System; CID, Inc., USA).

Total soluble proteins (TSP)

Total soluble protein content was determined using the biuret method described by27. The absorbance was measured at 545 nm using a UV spectrophotometer. A standard curve was prepared using bovine serum albumin to quantify the protein concentration.

Free proline

The estimation of free proline was carried out following an established protocol28. Proline was extracted using sulfosalicylic acid and then reacted with ninhydrin and glacial acetic acid. The mixture was subsequently treated with toluene and heated at 100 °C, after which the absorbance of the resulting toluene phase was recorded at 520 nm.

Leaves nutrient analysis

Nitrogen content in this study was assessed using a modified version of the micro-Kjeldahl method, originally described by29. Potassium levels were measured using a flame photometer. The yellow colorimetric method was applied for phosphorus determination, with absorbance recorded at 420 nm using a spectrophotometer, following the procedure outlined by30.

Glyphosate analysis

Dried leaf samples were ground into a fine powder using a stainless-steel grinder. For each sample, 1.0 g of powdered leaf material was weighed and transferred into a 50 mL centrifuge tube. Extraction was performed by adding 10 mL of acidified methanol (methanol:water: formic acid, 15:84:1, v/v/v). The mixture was vortexed for 10 min and sonicated for 30 min at room temperature. The extracts were then centrifuged at 10,000 rpm for 10 min, and the supernatant was collected for analysis. Quantification of glyphosate was performed using High-Performance Liquid Chromatography (HPLC). A C18 reversed-phase column was used for separation. The mobile phase consisted of a mixture of phosphate buffer (0.02 M, pH 2.5) and methanol (90:10, v/v), delivered at a flow rate of 1.0 mL/min. The injection volume was 20 µL. Calibration curves were constructed using glyphosate standard solutions in the range of 0.1–10 µg/mL, and the retention time was recorded for all standards and sample extracts.

Statistical analysis

Data analysis was conducted using standard statistical methods as described by31. OriginPro, Excel 365, and MS Office were employed for data processing and visualization. A two-factorial ANOVA was applied to compute the significance of the treatments. Paired comparison graphs were generated using the Fisher’s Least Significant Difference (LSD) test at a significance level of p ≤ 0.05. Additionally, OriginPro was used to construct Pearson correlation matrices, convex hull cluster diagrams, and hierarchical cluster plots32.

Results

The broad peak at ~ 3410 cm⁻1 corresponds to O–H stretching vibrations, indicating hydroxyl groups. The band near 3190 cm⁻1 is assigned to N–H stretching, associated with amine functionalities. A peak at 1615 cm⁻1 represents C=C stretching of aromatic structures, while the band around 1510 cm⁻1 corresponds to C=O stretching vibrations. The absorption band near 1410 cm⁻1 is attributed to C–O stretching, and the peaks at ~ 1230–1260 cm⁻1 represent P–O–C linkages. Additionally, P–OH bending vibrations were evident near 1070 cm⁻1 (Fig. 1; Table 2).

Fig. 1
Fig. 1
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FTIR for the characterization of tea waste biochar.

Table 2 FTIR peak positions, intensities, and functional groups.
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Under 0% ZL, adding 0.15%TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC treatments caused a significant increase in plant height (15.99%, 40.57%, 20.52%, and 36.78%), root length (17.95%, 40.56%, 24.24%, and 34.97%), and chlorophyll SPAD (23.54%, 48.86%, 30.36%, and 43.51%) and showed a decrease in proline (17.39%, 35.85%, 20.67%, and 29.34%) compared to control (0%TWBC). Treatments 0.15%TWBC, 0.30%TWBC, 0.60%TWBC, and 1.20%TWBC showed an increase in plant height (15.91%, 30.74%, 44.91%, and 38.64%), root length (12.73%, 27.93%, 49.69%, and 35.52%), chlorophyll SPAD (17.58%, 35.30%, 51.34%, and 40.79%) but decrease in proline (13.37%, 30.00%, 51.16%, and 35.42%) over control (0% TWBC) under 5% ZL (Fig. 2).

Fig. 2
Fig. 2Fig. 2
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Effect of tea waste biochar (TBC) and Zeolite (ZL) on plant height, root length, chlorophyll (SPAD), and proline in maize. Mean values (± SD) are based on three independent replicates. Variations among treatments were statistically verified using Fisher’s LSD at a 5% probability level, where non-matching letters denote significant differences.

Adding 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC treatments resulted increase in shoot fresh weight (16.93%, 37.37%, 20.91%, and 33.30%), shoot dry weight (8.49%, 30.66%, 12.83%, and 27.36%), root fresh weight (19.32%, 42.15%, 24.48%, and 38.53%), and root dry weight (10.05%, 31.25%, 15.76%, and 28.80%) over the control (0% TWBC) under 0%ZL. Treatment with 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC under 5% ZL exhibit an increase in shoot fresh weight (11.45%, 29.20%, 44.21%, and 33.46%), shoot dry weight (11.26%, 36.49%, 58.47%, and 40.99%), root fresh weight (13.96%, 31.67%, 52.55%, and 39.94%), and root dry weight (12.50%, 39.29%, 62.50%, and 45.41%) compared to control (0% TWBC) (Fig. 3).

Fig. 3
Fig. 3Fig. 3
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Effect of tea waste biochar (TBC) and Zeolite (ZL) on shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight in maize. Mean values (± SD) are based on three independent replicates. Variations among treatments were statistically verified using Fisher’s LSD at a 5% probability level, where non-matching letters denote significant differences.

Treatments 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC showed a rise in total soluble sugar (TSP) (12.07%, 32.18%, 16.67%, and 27.59%), free amino acid (FAA) (26.83%, 2.44%, 43.90%, and 7.32%) and caused a decrease in peroxidase (POD) (17.14%, 50.00%, 24.24%, and 41.38%), and ascorbate peroxidase (APX) (15.49%, 67.35%, 24.24%, and 46.43%) over control (0% TWBC) under 0% ZL. Treatment with 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC under 5% ZL exhibits an increase in TSP (12.83%, 29.95%, 44.39%, and 34.22%), FAA (41.30%, 2.17%, 17.39%, and 4.35%), and demonstrates a decrease in POD (19.35%, 44.16%, 76.19%, and 54.17%), and APX (27.87%, 77.27%, 99.41%, and 95.26%) than control (0% TWBC) (Fig. 4).

Fig. 4
Fig. 4Fig. 4
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Effect of tea waste biochar (TBC) and Zeolite (ZL) on total soluble sugar (TSP), free amino acid (FAA), peroxidase (POD), and ascorbate peroxidase (APX) in maize. Mean values (± SD) are based on three independent replicates. Variations among treatments were statistically verified using Fisher’s LSD at a 5% probability level, where non-matching letters denote significant differences.

Treatments 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC under 0% ZL exhibit a decrease in CAT (8.67%, 41.74%, 13.19%, and 26.36%), SOD (10.00%, 37.50%, 15.24%, and 27.37%), and glyphosate residue (9.47%, 40.54%, 16.85%, and 31.65%) in leaf and caused increase in glyphosate residue in soil (2.00%, 29.00%, 8.00%, and 20.00%) from the control (0% TWBC). Treatment with 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC under 5% ZL exhibits a decrease in CAT (17.04%, 43.64%, 66.32%, and 58.00%), SOD (17.00%, 40.96%, 60.27%, and 51.95%), and glyphosate residue in leaf (21.43%, 52.24%, 88.89%, and 64.52%) and caused increase in glyphosate residue in soil (22.83%, 46.74%, 69.57%, and 56.52%) from control (0% TWBC) (Fig. 5).

Fig. 5
Fig. 5Fig. 5
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Effect of tea waste biochar (TBC) and Zeolite (ZL) on catalase (CAT), superoxide dismutase (SOD), glyphosate residue in soil, and glyphosate residue in leaf in maize. Mean values (± SD) are based on three independent replicates. Variations among treatments were statistically verified using Fisher’s LSD at a 5% probability level, where non-matching letters denote significant differences.

Adding 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC treatment increased leaf N (5.01%, 18.00%, 8.35%, and 14.29%), leaf P (8.41%, 22.43%, 11.21%, and 18.69%), and leaf K (4.26%, 13.68%, 6.84%, and 11.55%) over the control (0% TWBC) under 0% ZL. Treatment with 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC under 5% ZL exhibits an increase in leaf N (8.56%, 18.03%, 23.50%, and 20.40%), leaf P (11.82%, 22.73%, 29.09%, and 25.45%), and leaf K (7.35%, 14.09%, 17.24%, and 15.59%) than the control (0% TWBC) (Fig. 6).

Fig. 6
Fig. 6Fig. 6
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Effect of tea waste biochar (TBC) and Zeolite (ZL) on leaf N, leaf P, and leaf K in maize. Mean values (± SD) are based on three independent replicates. Variations among treatments were statistically verified using Fisher’s LSD at a 5% probability level, where non-matching letters denote significant differences.

Applying 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC treatments caused an increase in photosynthetic rate (6.17%, 18.02%, 9.14%, and 14.81%), stomatal conductance (7.41%, 21.30%, 9.26%, and 16.67%), transpiration rate (15.79%, 0%, 23.68%, and 0.26%), and crude protein (6.33%, 25.33%, 10.67%, and 20.00%) over control (0% TWBC) under 0% ZL. Under 5% ZL treatment 0.15% TWBC, 0.30% TWBC, 0.60% TWBC, and 1.20% TWBC demonstrate an increase in photosynthetic rate (7.35%, 15.64%, 20.14%, and 17.54%), stomatal conductance (8.93%, 20.54%, 26.79%, and 23.22%), transpiration rate (21.95%, 0%, 17.89%, and 12.20%), and crude protein (9.32%, 24.12%, 31.19%, and 27.33%) over control (0% TWBC) (Fig. 7).

Fig. 7
Fig. 7Fig. 7
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Effect of tea waste biochar (TBC) and Zeolite (ZL) on photosynthetic rate, stomatal conductance, transpiration rate, and crude protein in maize. Mean values (± SD) are based on three independent replicates. Variations among treatments were statistically verified using Fisher’s LSD at a 5% probability level, where non-matching letters denote significant differences.

In PCA, the control group clustered on the negative side of PC1 and near the center of PC2, indicating a distinct biochemical and physiological profile. The 0.15% TWBC treatment shifted toward the center and slightly positive PC2 values, while 0.30% TWBC occupied the positive PC1 and negative PC2 region, showing greater influence on plant traits. The 0.60% TWBC treatment shifted further into the upper-right quadrant (positive PC1 and PC2), reflecting enhanced trait divergence. The 1.20% TWBC group extended along PC1 but overlapped partially with the 0.30% treatment, maintaining a unique though less pronounced effect profile (Fig. 8A).

Fig. 8
Fig. 8
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Cluster plot convex hull for different levels of tea waste biochar (TWBC) (A), zeolite (ZL) levels (B), and hierarchical cluster plot (C) for studied attributes.

For zeolite, the 0% ZL group clustered compactly in the negative PC1 region with limited variability (PC1: − 7.6585 to + 2.4423; PC2: − 2.3133 to + 1.7532). In contrast, the 5% ZL group displayed a broader and more dispersed convex hull (PC1: − 5.7645 to + 8.0592; PC2: − 1.1314 to + 2.5873), highlighting greater variability and physiological response to treatment (Fig. 8B).

Hierarchical clustering further clarified trait associations (Fig. 8C). Shoot fresh weight clustered with chlorophyll content at the highest similarity (0.063), while shoot and root dry weights formed another close cluster (0.106). CAT activity grouped with soil glyphosate residue (0.145), and leaf N with leaf K (0.178), reflecting nutrient interactions. Plant height clustered with photosynthetic rate (0.334), and stomatal conductance with crude protein (0.350), underscoring their functional relationships. In contrast, glyphosate residue in leaves clustered separately (0.310), proline appeared at a much lower similarity (1.139), and antioxidant enzymes (POD, SOD, APx) only joined at very high dissimilarity (> 10), indicating distinct stress-related behavior. The transpiration rate formed the most distant cluster (48.84), confirming its unique regulation compared with other traits (Fig. 8C).

Plant height showed strong positive correlations with root length (r = 0.988), shoot fresh weight (r = 0.993), root fresh weight (r = 0.992), shoot dry weight (r = 0.970), and root dry weight (r = 0.966), indicating that taller plants were associated with greater biomass accumulation in both aboveground and belowground parts. Similarly, all growth parameters were highly positively correlated with chlorophyll content (r ranging from 0.966 to 0.995), photosynthetic rate (r = 0.995), and crude protein content (r = 0.990), showing close associations between plant vigor and photosynthetic performance. Chlorophyll content was positively correlated with most growth parameters and photosynthetic rate (r = 0.991). Proline content showed strong negative correlations with plant height (r = − 0.988), shoot and root biomass (r ranging from − 0.959 to − 0.992), and chlorophyll (r = − 0.997), consistent with its typical association with stress-related growth decrease. Antioxidant enzymes such as POD, SOD, CAT, and APx showed strong and significant negative correlations with growth and physiological traits (r ranging from − 0.96 to − 0.997), but strong significant positive correlations among themselves (r > 0.978), reflecting their coordinated response pattern. Soil glyphosate residue exhibited a strong positive correlation with plant height (r = 0.884), biomass accumulation (r > 0.88), and photosynthesis (r = 0.879). In contrast, glyphosate residue in leaves showed strong negative correlations with all growth traits (r < − 0.96), photosynthesis (r = − 0.971), and chlorophyll content (r = − 0.972), suggesting that higher glyphosate accumulation in tissues was associated with reduced plant physiological performance. Leaf N, P, and K contents were positively correlated with growth traits (r > 0.95), chlorophyll (r > 0.97), and crude protein (r > 0.98) while negatively correlated with antioxidant enzyme activities (r < − 0.97), showing links between nutrient status, growth, and oxidative stress. Photosynthetic rate was strongly correlated with plant height (r = 0.995), chlorophyll (r = 0.991), crude protein (r = 0.994), and stomatal conductance (r = 0.994). Stomatal conductance was positively correlated with most growth parameters (r > 0.97). Transpiration rate showed moderate to weak correlations with growth parameters but a notably strong positive correlation with FAA (r = 0.939), suggesting a close association with nitrogen metabolism (Fig. 9).

Fig. 9
Fig. 9
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Pearson correlation analysis for the studied attributes.

Discussion

Soil residual glyphosate

Disturbance in the soil ecological balance, resulting in low crop productivity due to the persistence of glyphosate residues in the soil, has raised increasing concern. Besides its short half-life, it can become concentrated in the soil matrix due to continuous and over-application33. Glyphosate sorption in soils is largely controlled by interactions with Fe and Al oxides, clay minerals, and organic matter, with reported adsorption coefficients (Kd) ranging from 10 to 150 L kg⁻1 and organic carbon partition coefficients (Koc) between 300 and 2000, depending on soil type and environmental conditions. The presence of competing anions such as phosphate, nitrate, and sulfate further complicates this behavior, as they compete with glyphosate for binding sites and can markedly reduce its sorption, thereby enhancing its mobility34,35. Residual glyphosate can alter microbial community structure by selectively inhibiting sensitive taxa while favoring glyphosate-tolerant microorganisms, potentially reducing microbial diversity and enzymatic activity essential for nutrient cycling36. Moreover, concerns have been raised about the potential leaching of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) into groundwater, especially under sandy or low pH soils, posing risks to water quality and human health37.

Tea waste biochar (TWBC)

The carbon-rich product TWBC, which originates from tea production waste created through pyrolysis, shows substantial effectiveness in enhancing the stress-resilience of soil while boosting its physical and chemical characteristics38. The porous structure of TWBC helps roots receive adequate air and water, which creates a suitable soil environment for plant root development39. The high surface area and numerous functional groups, such as hydroxyl carboxyl and carbonyl in TWBC, make it an exceptional material for adsorbing agrochemical residue, including glyphosate40. The adsorption mechanism of glyphosate into the rhizosphere decreases its availability, preventing harmful effects upon plants’ metabolic processes. The addition of TWBC in the study positively affected photosynthetic activity while boosting chlorophyll levels and raising nutrient absorption, particularly nitrogen needed for chlorophyll production and amino acid generation41,42. TWBC reduces the accumulation of reactive oxygen species (ROS) and limits glyphosate-induced oxidative stress by reducing POD and CAT activities. The dual role of TWBC emerges as a stress mediator and growth promoter through enhancing physiological stability and improving access to available resources43. Several studies have reported adsorption capacities of biochars for glyphosate ranging from approximately 44 mg g⁻1 (for woody biochar) to as high as 123 mg g⁻1 (for steam-activated rice husk biochar under optimized conditions)44. However, the sorption efficiency can be influenced by the presence of competing anions such as phosphate, nitrate, and sulfate, which compete for the same active sites on the biochar surface and thus may reduce glyphosate binding45.

Zeolite (ZL)

The natural aluminosilicate mineral zeolite (ZL) shows crucial importance in sustaining soil fertility together with plant stress tolerance against glyphosate exposure through its high cation exchange capacity (CEC)9,46. ZL crystalline structure allows cation adsorption, including NH₄⁺ K⁺ and Ca2⁺ within the soil, which promotes both nutrient retention and reduces leaching losses47. The combination of a 5% ZL solution with TWBC applied to maize fields enhanced all growth parameters, including shoot development, root length, photosynthesis rates, and protein content. The ion-absorption qualities of zeolite regulate soil pH levels while creating barriers that hinder glyphosate migration through the soil system48. This behavior decreased glyphosate accumulation in plant tissues and enhanced glyphosate storage within the soil system. Zeolites have also demonstrated direct adsorption of glyphosate, with modified forms, such as Cu-exchanged zeolite 4A, showing maximum adsorption capacities of up to 112.7 mg g⁻1. Beyond glyphosate, natural zeolites richly adsorb nutrients—clinoptilolite-amended columns reduced leaching loss by 82% compared to control in loamy sand systems9,49. ZL promotes microbial activities and root-zone oxygenation while working in combination with TWBC to enhance soil fertility9. ZL-treated plants displayed lower enzyme activities of stress-responsive POD, SOD, and CAT as a sign of successful oxidative damage prevention. ZL promotes nutrient dynamics and creates beneficial rhizosphere conditions that benefit sustainable plant growth under stressful environments50.

Although the present findings clearly demonstrate the potential of TWBC and ZL in improving plant growth and reducing stress indicators, it is important to acknowledge certain limitations. The experiment was conducted under controlled pot conditions, which may not fully capture the complexity of field environments where soil heterogeneity, rainfall, microbial interactions, and long-term nutrient dynamics can influence outcomes. Therefore, further validation through multi-season field trials is required to confirm the consistency and scalability of these results. From a practical perspective, the combined application of TWBC and ZL appears promising for farmers, as tea waste biochar is a low-cost material that can be produced locally, while zeolite is increasingly available in agricultural markets. Together, these amendments not only enhance crop growth and stress resilience but also provide a cost-effective and environmentally friendly approach to sustainable soil management.

Conclusion

In conclusion, 0.6% of TWBC and 5% of ZL increases maize growth under glyphosate stress. Additionally, the 0.6% TWBC with 5% ZL treatment can regulate antioxidant levels, increase essential nutrient concentration, and reduce the negative effects of glyphosate on maize. Beyond enhancing plant growth and physiological resilience, these amendments contribute to improved soil quality, which are central to sustainable crop production. These results suggest that integrating such low-cost and eco-friendly amendments into conventional farming practices could provide farmers with practical tools to balance productivity and environmental safety. Growers should consider using 0.6% TWBC with 5% ZL treatment to alleviate glyphosate stress in maize plants. However, recommendations require field validation under diverse conditions and cost–benefit analysis to ensure practical adoption.