The Khyber Pakhtunkhwa agricultural research center provided the Zea mays L., Triticum aestivum L., and Abelmoschus esculentus (L.) Moench seeds for this study. The pot experiments were conducted in greenhouse of Bacha Khan University Charsadda. It has 126 pots and three replicates for each dose/application. The soil was collected from agricultural field of District Charsadda and subjected to below different As and Ser concentrations;

Set 1

Control (only distilled)

Set 2

As = 25, 50, 75 and 100ppm

Set 3

As × Ser = 50× 25, 50×50, 50× 75, 50× 100

Set 4

As × Ser = 100× 25), 100×50), 100× 75 and 100ppm× 100ppm.

The soil was air-dried for seven days before being gently hammered to break up large pebbles. The dust was completely mixed after the undesirable components like dried roots, grass, and stones were taken out.

Agronomic parameters

The plant was collected after 21 days, and agronomic aspects like root length and number, shoot length, and leaf numbers were measured and examined.

Investigating the biochemical components

Assessment of biological components

The parameters listed below were measured using a variety of techniques for the biochemical analysis.

Extraction         

Fresh leaves were crushed in a mortar with 10ml of distilled water and centrifuged for 10 minutes at 1000 rpm. The supernatant was collected in a new test tube, and the remaining liquid was discarded.

Examining the leaf's protein components

Bradford's Assay reagent was used to extract and measure soluble protein [24].

Extraction of soluble proteins

0.2 g of leaf tissue should be homogenised in 5 ml of phosphate buffer (0.1 m, pH. = 7) using a very cold pestle and mortar. Through cheesecloth or glass wool, filter the homogenised or extracted material. The extract was centrifuged at 4000 rpm for 10 minutes after cooling. The supernatant was transferred to a test tube, and the extract volume was raised to 5 ml using buffer. We diluted the extract by 0.2 mL by adding it to a 4.8 mL buffer (this extract will provide dilution).

Analysis of soluble proteins

There was 0.1 mL of susceptible extract in a check tube. After shaking the extract, 5 mL of Bradford assay were added. With 5 mL of Bradford assay reagent and 0.1 mL of buffer, create a blank reagent. Using a spectrophotometer, the optical density (O.D.) at 595 nm was calculated. The amount of readily soluble protein is determined by an extended curve.

Determination of carotenoids and chlorophyll

Chlorophyll and carotenoids were extracted and quantified using the Maclachlan and Zalik [25] method. A fresh crushed leaf is dissolved in 3 ml of 80% acetone with a tiny quantity of acid-cleared sand, centrifuged for five minutes at 1000 rpm, and then dried. After that, the item is cleaned three times with one milliliter of acetone. Up to 7 mL of the supernatants are mixed with acetone. After that, this data's visual densities at 663nm, 645nm, 480nm, and 510nm were measured.

Equations

Proline's assessment of Leaves

The leaf proline contents were determined using the Bates et al. [26] method. After being homogenised with % sulphate salicylic acid and filtered through filter paper, 2 ml of extract was combined with 2 ml of glacial acetic acid and 2 ml of ninhydrin acid in a test tube for 1 hour at 100°C. An ice bath was used to end the procedure. After adding 4 ml of toluene and extracting the chromophore for 15 to 20 seconds, the tube was kept in place until all phases had separated. The chromophore that contained toluene was then transferred to a brand-new test tube. At 520 nm, the absorbance was measured. At 520 nm, the absorbance was measured.

Statistical analysis

The one-way ANOVA was performed Least Significant Difference (LSD) at a 5% level using the SPSS 16 (version 16), and graphs were drawn on Origin Pro 10.5v.

Effect of As on roots length of selected crops under the treatment of Ser foliar spray

The effect of As on length of root Abelmoschus esculentus L., Triticum aestivum L., and Zea mays L. under Ser treatments is shown in Table 1. The maximum root length (14.75±1.060) of Triticum aestivum L. was detected at a treatment of 75ppm (As)/50ppm (Ser), while the minimum (10.00±2.82) root length was observed at a treatment of 100 ppm (As)r). In trials conducted in pots, Zea mays L., the greatest root length (17.00±2.82) at treatment was 50 ppm(As)/100 ppm (Ser). Zea mays L. had a minimum (11.60±4.38) root length at treatment of 75ppm (As)/100ppm (Ser). In a similar manner, Abelmoschus esculentus L. data indicated that the maximum length of root was (7.00±0.70) at treatment 75 ppm (As)/100 ppm (Ser), and the minimum root length was 3.00±1.41 at treatment 50 ppm (As). These results suggested that the influence of individual dose of As was maximum, whereas the adverse effect reduced after the foliar spray of Ser.

Effect of As on root number of selected crops under Ser foliar spray

A limited length of time during the vegetative stage was used to evaluate plant samples from the planned experiment under As stress Table 2. After twenty-one days of pot research, the highest root number (14.50±2.12) was discovered, but Triticum aestivum L. had the lowest root number (8.02±0.94) at the same treatment level of 100 ppm (As). According to the Zea mays L. data, the maximum root number was recorded at 14.501±2.02 under the treatment of 100 ppm(As)/100 ppm(Ser), while the lowest root number was 10.503.53 measured under the treatment of 100 ppm(As). Similar to this, the Abelmoschus esculentus L. plant results indicated a maximum root number of 22.00±5.65 at treatment 100 ppm (As)/100 ppm (Ser), and a minimum root number (5.00±1.41) after 21 days at treatment 50 ppm (As) (Table 2). The findings showed that Ser lessened As negative effects.

Influence of As on Shoot Length of selected crops under the Ser treatment

After 21 days of germination, the shoot maximum length (6.00±0.00) of Triticum aestivum L. was detected in treatment at 50 ppm (As)/100 ppm(Ser), while the minimum shoot length was 3.50±0.70 after treatment at 75 ppm (As) (Table 3). In pots investigation for Zea mays L., the maximum shoot length (7.65±1.20) of Zea mays L. was observed in 100 ppm(As)/100 ppm(Ser), whereas the shoot smallest length was 4.25±0.07 at treatment 50ppm (As). Similarly, the maximum shoot length (5.85±0.35) of Abelmoschus esculentus L. was observed at treatment 75ppm (As)/100 ppm (Ser) and the smallest shoot length was 3.65±0.35 at treatment 100ppm (As) (Table 3). These results showed that the Ser reduced adverse effect of As on the shoot length of selected crops. 

Effects of As stress on leaf number on selected crops in the field in respect to Serine

Abelmoschus esculentus L., Zea mays L., and Triticum aestivum L. were among the crops assessed for leaf number under As stress in Table 4. For the majority of the treatments, the maximum leaf number of Triticum aestivum L. (5.00±1.00) was noted for 50ppm(As)/100ppm(Ser) and control treatment. The 4.00±0.00 leaf no was absorbed for the remaining treatments. This showed that the influence of As relatively weak on leaf no of Triticum aestivum L. Zea mays L. exhibited its maximum leaf number (5.00±0.00) after 21 days of germination in all treatments with the exception of control, 75, and 100ppm (As). Abelmoschus esculentus L. similarly revealed 3.00±0.00 number of leaves at 21 days for all treatments examined, with the exception of control, 50 and 100 ppm (As). This demonstrated that Zea mays L. and Triticum aestivum L. were less substantially impacted by As than Abelmoschus esculentus L. (Table 4).

As influence on the Chl. “a”, “b” and total Chl. contents (mg/g) of Zea mays L. growing under the Ser applications

The Photosynthetic pigments of Zea mays L. were shown in Figure 1. Chl. "a" contents maximum for the treatments at 50ppm (As)/50ppm (Ser) and at their lowest for the treatments at 100 ppm (As). Similar to this, the maximum Chl. "b" and total Chl. contents were observed for treatments with 50-ppm (As) / 50-ppm (Ser) and minimum for 100-ppm (As). The outcomes demonstrate that Chlorophyll "b" was greater than Chlorophyll "a" in all treatments, whereas Chl. "a," "b," and total Chl. content (mg/g) of Zea mays L. were relatively variable compared to the control treatment. This demonstrated that Ser mitigated the negative effects of As because Chlorophyll "b," in particular, was produced at the highest dosage of Ser.

Effect of As on Chl. "a" and "b" and Total Chl. of Abelmoschus esculentus L. grown in Ser applications

Figure 2 displays the effect of As on photosynthetic pigments of Abelmoschus esculentus L. under the Ser foliar spar. The maximum chlorophyll "a" as observed in treatments of 50ppm (As)/100ppm (Ser), while the lowest was shown with treatments of 25ppm (As). In treatment of 100ppm (As)/100ppm (Ser) had the maximum content of chlorophyll "b" was observed.  The maximum total chlorophyll content was reported for 100ppm (As)/100ppm (Ser) treatment and minim total chlorophyll pigment observed at treatment 25ppm(As). These results reveal that Chlorophyll "a" and Chlorophyll "b" responded differently to treatments, but overall Chlorophyll content (mg/g) and Chlorophyll "a" and "b" content (mg/g) of Zea mays L. were increased in various treatments when compared to control treatment.

Effect of As on photosynthetic pigments of Triticum aestivum L. growing under the Ser treatments

Figure 3 shows the influence of As on photosynthetic pigments of Triticum aestivum L. under the Ser foliar spray. The minimal quantity of chlorophyll "a" and “b” observed for the treatment 75 and 100ppm of As, while the greatest content was detected for treatment at 100ppm (As)/100 ppm (Ser). Similarly, the maximum content of total chlorophyll content was observed (Ser) at 100ppm (As)/100 ppm (Ser). According to the findings, higher Chlorophyll "a" than Chlorophyll "b" was formed. This showed that Ser, in particular Chlorophyll "a," prevented As from having a negative impact on Triticum aestivum L. at levels above their limit. These results suggested that Chl “a”, “b”, and Total Chl. contents of Triticum aestivum L. were greater in As+Ser usages as compared to the control and individual doses of As (Figure 3).

Effect of As on protein contents under Ser treatments of selected crops

Results indicated that Zea mays L. treatments at 50-ppm (As) / 100-ppm (Ser) had the highest protein content, followed by treatments at 50-ppm (As) / 50-ppm (Ser) of Abelmoschus esculentus L., and Triticum aestivum L., flowing by treatment 25-ppm (As) / 50-ppm (Ser). The lowest contents of protein were detected for Zea mays L. at treatment 75-ppm (As) / 50-ppm (Ser); Abelmoschus esculentus L., and Triticum aestivum L. at treatment 50-ppm (As), respectively (Figure 4). These results demonstrated that when exposed to produced Ser had a favorable impact on protein content.

Effects of As on proline (g/g) concentration under Ser foliar spray on selected crops

The results indicated that Abelmoschus esculentus L., Zea mays L. and Triticum aestivum L. had the greatest proline contents for treatment, each at 100 ppm (As). The lowest proline concentration Triticum aestivum L. was found in control, which flowed by Zea mays L. at treatment 50-ppm (As) / 100-ppm (Ser) and Abelmoschus esculentus L.at treatment 50-ppm (As)/100 ppm (Ser), respectively (Figure 5). These findings indicate that Ser functions under induced As as an upbeat proline content improver.

Effect of As on carotenoid ( g/g) concentration of selected crops under Ser to Arsenite foliar spray.

The findings revealed that Zea mays L. flowered by Triticum aestivum L. in treatment 75-ppm (As) / 100-ppm had the highest carotenoid content (Ser), followed by Zea mays L. and Triticum aestivum L at treatment 75-ppm (As) / 100-ppm (Ser), respectively (Figure 6). Abelmoschus esculentus L. had the lowest carotenoids content at treatment 50-ppm (As) compared to Zea mays L. and Triticum aestivum L. 

Soil analysis for heavy metals

Data suggest that the heavy metals are affected by the addition of Ser and As (Table 5). Higher Mn value observed for treatment As × Ser (100-ppm × 100-ppm) and minimum for control. The higher quantity of Pb and Cr observed for As × Ser (50-ppm × 25-ppm) and As × Ser (100-ppm × 25-ppm), respectively. Similarly, the maximum quantity of Zn was reported for As × Ser (50-ppm × 75-ppm), As × Ser (100-ppm × 25-ppm) for Zn, As (75-ppm) of Ni and Cd. The higher quantity of As was reported for As (100-ppm), whereas low As documented for control treatments (Table 5).

Figures & Tables

Discussion

In various investigations, the effects of serine treatments on the growth and biochemical makeup of Zea mays L. (maize), Triticum aestivum L. (wheat), and Abelmoschus esculentus L. (okra) under the impacts of arsenic effects have been examined. This research provides insight into serine's capacity to mitigate arsenic's harmful effects on plants. The serine affectedly enhanced growth indices in maize plants under arsenic stress. Compared to plants exposed to arsenic without serine addition, treated plants had longer roots and shoots, greater biomass accumulation, and more chlorophyll [27]. These findings suggest that serine stimulates maize plant development in arsenic-toxic environments. Similar to this, Nahar et al.  [28] examined into the effects of serine on arsenic-exposed plant seedlings. In this study, wheat plants treated with serine showed noticeably better growth characteristics, including plant height, leaf area, and wet weight.

These findings suggest that serine treatments can promote wheat plant development under the stress arsenic stress. Similarly, Mairuae et al. [29] investigated the impact of serine on okra plants grown under arsenic-toxic circumstances. This study demonstrated that serine treatment enhanced the growth of the okra plant, including increased plant height, roots, and biomass accumulation. this provide credence to the idea that serine augmentation might encourage okra plant development even in the presence of arsenic-induced stress. Serine treatment has been demonstrated to impact the biochemical constituents of plants subjected to arsenic poisoning in addition to growth metrics. The negative effect of As on photosynthetic pigments depending on the levels of As [5,30,31]. Similarly Rice (Oryza sativa L.) seedlings experience biochemical and molecular changes as a result of chromium stress [32].  Sharma et al. [33] reported that low doses of As (0.25 mg L¹) reduced the plant biomass, chlorophyll content, shoot and root elongation relative to control. The serine-treated maize plants had higher amounts of proline and soluble carbohydrates [34]. These substances have significant effects on osmotic control and stress tolerance, suggesting that plants treated with serine have enhanced physiological responses.

Different concentrations of proline applied to the leaves aid in minimising the detrimental effects of different stress [35]. A typical plant response to environmental stresses, such as low light levels and/or heavy metal stress, is proline buildup. Proline metabolism has been proposed to modulate cellular redox status and radical detoxification as additional functions of proline accumulation. [36]. In addition, the study found that plants treated with serine had higher levels of antioxidant enzymes such superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). A superior defence against oxidative stress brought on by arsenic poisoning is provided by serine supplementation, as evidenced by the increased enzymatic activity [37]. A comparable result was seen in wheat plants that had received serine treatment. In this work, arsenic-induced stress led to higher proline accumulation in wheat plants treated with serine. These findings imply that the antioxidant defence systems may stimulated by serine aid wheat reduce the negative effects of arsenic-induced oxidative stress. The effects of serine on okra plants were studied by Mokgalabone et al. [38]. They discovered elevated proline levels and increased antioxidant enzyme activity, which are comparable to those observed in maize and wheat research. These findings suggest that serine supplementation boosts okra’s ability to withstand stress brought on by arsenic by strengthening its antioxidant defences and osmotic control. There are several pathways that may account for serine’s favourable effects on plant development and the biochemical components of arsenic toxicity. Serine is involved in the production of crucial metabolites including glutathione (GSH) [39], which is crucial for the chelation and subsequent sequestration of arsenic. A precursor for the synthesis of other amino acids including glycine, cysteine, and methionine, which are necessary for the creation of antioxidant enzymes and other protective compounds, serine also plays the role of an amino acid. Although, serine treatments promoted Zea mays L., Triticum aestivum L., and Abelmoschus esculentus L. plant growth and biochemical composition under arsenic poisoning circumstances. The changes in biochemical composition, growth indices, and antioxidant defence systems all point to serine's potential as a stress-relieving compound in the presence of arsenic. However, further research is required to fully understand the underlying processes and to optimise the use of serine to improve crop resistance to arsenic.

A pot experiment was conducted to investigate the effect on plant growth and photosynthetic pigments. The experiment was designed with three replications of thirteen As and As+Ser treatments. Individual (As) treatment of As adversely affect the agronomic parameters of selected planets, whereas the influence of As reduced after the application of Ser. Similarly, the physiological analysis of selected crops such as Triticum aestivum L., Zea mays L. and Abelmoschus esculentus L. showed a minor negative influence after the Ser applications. Photosynthetic pigments, protein, and carotene content of the selected crops were reduced with treatment of As concentrations compared to As+Ser and control treatment. The proline formation was maximum at the higher dosage of As (particularly 100ppm (AS)) in Zea mays L., Triticum aestivum L., and Abelmoschus esculentus L. Low concentrations of heavy metals that are significant for the environment should receive further consideration. As a result, a variety of strategies must be combined with increasingly sensitive detection techniques.

Conflict of Interest

The authors declare no conflict of interest.

Author Contributions

All authors contributed equally to this study.