Introduction

Naturally, plants are subjected to many adverse environmental circumstances like abiotic and biotic stresses. Trace element stress is of great interest which has remarkable harmful effects on crop growth and productivity (Gill 2014). The increased agricultural dependence on sewage wastewater irrigation, chemical fertilizers and rapid development of industry have increased amount of toxic metals in agricultural soils resulting in detrimental effects on soil–plant environment system (Gadallah and Sayed 2014; Jali et al. 2016).

Cadmium is a poisonous metal and is regarded with a major environmental concern to the agricultural system. The divalent cation (Cd2+) is almost exclusively present in fertilized soils and accompanied with inorganic and organic complexes. Many studies have now found that the free Cd2+ ion or Cd complexes by inorganic ligands is the predominant Cd species exist in the soil solution of most soils. Furthermore, Cd is constantly, cumulated in soil, throughout anthropogenic and natural resources, for example, weathered cadmium-rich rocks, smelting, mining, the application of sewage sludge or excessive use of phosphate fertilizers, and metal contaminated water for crop irrigation (Alloway 2013; Hooda 2010; Kabta-Pendias 2011).

Cd is absorbed rapidly via plant roots and accumulates in plants to concentrations that could potentially cause animal toxicity. Cadmium uptake by plants is affected by array of variables—plant cultivar, pH of soil, salinity, mineralogy and organic matter content, cation interchange ability and concentrations of other nutrients, especially N, P and Zn (Burzynski et al. 2005; Clemens et al. 2013; Migocka et al. 2011; Plaza et al. 2015; Verbruggen et al. 2013). Cadmium solubility is greatest in acidic soil. The toxicity of Cd due to its high solubility and mobility within the ecosystem (Groppa et al. 2012; Jali et al. 2016) affects plant growth, induces necrosis and chlorophyll degradation and changes nutrient absorption, protein metabolism, carbon fixation and membrane functioning (Abdallah et al. 2015; Ahmad et al. 2015; Jali et al. 2016; Khan et al. 2013; Shah et al. 2017; Singh and Prasad 2014). Furthermore, cadmium enhances the activeness of antioxidant enzymes (Peng et al. 2017) and has high affinity towards the sulfhydryl groups of enzymes (Mendoza-Cozatl et al. 2005). Ultimately, cadmium prompts oxidative stress through its elevated affinity for carboxyl, SH and amine groups of the proteins (DalCorso et al. 2008).

Hydrogen peroxide is a paramount cellular molecule, performs numerous functions in metabolism, development and constancy of aerobes (Bienert et al. 2006). It’s generation increased is due to various stress conditions (Neill et al. 2002). Hydrogen peroxide acts as an essential reactive oxygen species in signal transmission paths which activates plant defences against different imposed ecological stresses (Xu et al. 2011). In plants, H2O2 is the mostly stable ROS and can regulate vital metabolic pathways, as defence, development as well as, acclimation (Ślesak et al. 2007) and guard cell signaling (Song et al. 2014).

H2O2 is relatively stable molecule, more diffusible through membranes, considered as a long distance signal component (Vranová et al. 2002), can trigger Ca2+ influxes, protein alterations and gene expression (Bienert et al. 2006).

During the last decades, the acclimatory role of this component in plant has progressively become an interested fact. External H2O2 applications concurrently stimulated multi-tolerance mechanism towards cold, heat, drought and salinity stresses in Zea mays seedlings (Gong et al. 2001). AzevedoNeto et al. (2005) and Uchida et al. (2002) explained that addition of H2O2 to nutrient solution inducts acclimatization to salt stress in maize and rice seedlings. Also, Ismail et al. (2015) reported that H2O2 have regulatory impacts on plant growth, evolution and nutritional value of fruits. Hossain et al. (2015) indicated that H2O2 pretreatment improves abiotic oxidative stress acclimation. On Brassica napus, the hydrogen peroxide pretreatment mitigates cadmium stimulated oxidative stress damage (Hasanuzzaman et al. 2017). Khan et al.(2017) established that the seedlings of Brassica subjected to water-deficient condition that were supplied with H2O2 and Ca2+ recovered from chlorosis, overcoming water loss in plant, and the plants were able to grow normally. The exogenous H2O2 application has been accompanied by an increasing in its endogenous production (Terzi et al. 2014).

Considerable scientists confirmed the detrimental impacts of Cd on the outgrowth of plants, however; publications’ concerning the ameliorating effects of H2O2 in cadmium-stressed plants is scarce. In addition, responses of plants to H2O2 foliar application and Cd stress are not still recognizable. Our study was performed with the assumption that H2O2 application able to modulate the adverse influence of cadmium stress on pea growth. Therefore, we investigated effects of foliar H2O2 spraying on improving cadmium stress tolerance of Pisum sativum and whatever the protecting effect was associated with some metabolic regulation in the shoots and roots tissues.

Materials and methods

Growth conditions and treatments

Seeds of Pisum sativum L. (cultivar Master B) were achieved from the Agricultural Research Center, Giza, Egypt. Plants was cultivated in plastic pots holding 4 kg of clean and air dry soil (clay/sand 2:1) in the experimental greenhouse in normal field conditions of humidity, temperature, light, and day/night pattern at Botany and Microbiology Department, Faculty of Science, Assiut University (Egypt). Extract of this soil records an electrical conductivity (EC) and pH as 0.876 mS cm−1 and 7.83, respectively. Three plants in each pot were allowed to grow for 5 weeks; water content of the soil kept at field capacity. Plants irrigated twice with 500 cm3 full strength nutrient solution (Down and Hellmers 1975). The stock nutrient solution composited (mM) of: KNO3 100; Ca (NO3)2 100; MgSO4·7H2O 100; NH4H2PO4 100; KCl 50; H3BO3 25; MnSO4·H2O; ZnSO4·7H2O2; CuSO4·5H2O 0.5; H2MoO4 0.5 and Fe·EDTA 20 mM.

Various treatments applied for pot experiments were classified to control (C), Cd stress (Cd) and, Cd stress combined with H2O2 (Cd + H2O2). Five-week-old plants were irrigated with (900 ml/pot) 0.00, 0.125, 0.250, 0.500 and 1 mM CdCl2·2.5 H2O. Soil was irrigated 5 times at 3 day intervals with these solutions. Cadmium solution was applied without nutrient solution. After 2 weeks of Cd supplying one set of the plants (0.0, 0.125, 0.250, 0.500 and 1 mM CdCl2·2.5 H2O) was foliar sprayed with distilled water, the second set was foliar sprayed with 1 m M H2O2 solution, and the third set was foliar sprayed with 2 m M H2O2 solution. Foliar applications were done three times at 3 day intervals. H2O2 solutions were prepared from stock solution (1 M/100 ml distilled water). All treatments took place at the same time (at the end of the day). The concentration of Cd and H2O2 were chosen from the preliminary results. Randomly, five replicates were allocated to each treatment combination at each application. Seven days following preceding foliar (three times at 3 days intervals) H2O2 applications, the plants were analyzed.

Determination of soil electric conductivity (EC) and pH value

Electric conductivity (EC) of the soil was measured employing conductivity meter (model 4310 JEN WAY), as stated by the methods from Jackson (1967). Soil water extracts (1:5) was prepared by shaking 40 g of dry soil with 200 ml distilled water for 2 h, then filtrated to obtain a clear filtrate. Soil reaction of the filtrate was measured using electric pH-meter (model pH-206, Lutron).

Determination of photosynthetic pigments

Chlorophylls (a and b) and carotenoids were extricated from fresh leaves (0.25 g in 10 ml 95% ethyl alcohol) and absorbance readings measured spectrophotometrically (Unico UV-21 00, Unico, USA). The absorption was measured at 645 nm (Chl a), 663 nm (Chl b) and 470 nm (carotenoids). Chlorophylls and carotenoids concentrations (as mg g−1 FW) were estimated using equations as cited by Wellburn (1994).

Hydrogen peroxide (H2O2) determination

H2O2 content was determined by crushing 0.5 g fresh tissues of plants with 5 ml of trichloroacetic acid (TCA 0.1%) and centrifuged at 12,000×g for 15 min at 4 °C. To 0.5 ml of the supernatant, 0.5 ml of 10 mM potassium phosphate buffer (pH = 7.0) and 1 ml of 1 M KI were added. Absorbance was measured at 390 nm (Unico UV-21 00, Unico, USA). Concentration of H2O2 estimated as μmol g−1 FW (Velikova et al. 2000).

Determination of malondialdehyde (MDA)

A lipid peroxidation level was assessed by determination of malondialdehyde (MadhavaRao and Sresty 2000). 0.2 g fresh tissues sample of plants was crushed in 5 ml 0.1% TCA and centrifuged at 10,000×g for 5 min. 4 ml of 20% TCA containing 0.5% thiobarbituric acid (TBA) was added to 1 ml of the supernatant aliquot. Mix was incubated at 95 °C for 15 min and immediately cooled. The non-specific absorbance of the supernatant at 600 nm was deducted from the maximal absorbance at 532 nm utilizing spectrophotometer (Unico UV-21 00, Unico, USA). The concentration (μmol g−1 FW) of malonydialdhyde was recorded using (ϵ = 155 mM−1 cm−1).

Determination of ascorbic acid content

Ascorbic acid concentration (μmol g−1 FW) assayed as designated by Mukherjee and Choudhuri (1983) through mingling 2 mol l−1 Folin-Ciocalteu reagent and 10% TCA with 20% of fresh tissue homogenate. After 10 min of centrifugation, the blue colour established in the supernatant was measured at 760 nm (Unico UV-21 00, Unico, USA). Ascorbic acid concentration was determined from a standard curve using different concentrations of ascorbic acid.

Determination of soluble carbohydrates and nitrogen metabolites

Contents of soluble sugars, total free amino acids and soluble proteins were recorded spectrophotometrically in hot water plant extract of both root and shoot tissues.

Content of soluble sugars was measured using phenol-sulfuric acid procedure of Dubois et al. (1956). One ml of 5% (v/v) phenol followed by 5 ml of sulfuric acid was appended, respectively, to a known volume of plant sample. The previous mixture was stirred and cooled in room temperature for 15 min. Absorbance was registered at 490 nm. Calibration curve using glucose was constructed.

Amino acids and soluble protein contents were determined utilizing the ninhydrin reagent (Lee and Takahashi 1966) and folin–phenol reagent (Lowry et al. 1951) procedures. Calibration curves using glycine and bovine serum albumin as standard was, respectively, constructed.

Proline content determination

Proline extracted from plant fresh tissue samples, its concentration was recorded following the methods of Bates et al. (1973). Fresh tissue samples were powdered in 3% sulphosalicylic acid; centrifuged at 3000×g for 20 min. The supernatant reacted with glacial acetic acid, ninhydrin reagent, boiled for 1 h and cooled. The developed colour was detached in toluene stratum and the absorbance estimated at 520 nm spectrophotometrically (Unico UV-21 00, Unico, USA). Proline was stated as μmol g−1 FW.

Statistics

Analysis of variance (ANOVA) with post hoc Duncan (1955) Multiple Comparison test was performed applying SPSS of Windows (Ver. 13.0, SPSS Inc., USA). Significance concerning the means among control and treatments were estimated using probability level p < 0.05. The values of H2O2 treatment were compared with those of Cd at each Cd level.

The relative role of each factor on the entire influence of treatment combination was calculated from the coefficient of determination (η2).

$$\eta^{ 2} = \frac{\text{Sum of squares due to the factor}}{{{\text{Total sum of squares due to the treatment}}\,{\text{combination}}}}$$

Experimental results

Growth

Results in Table 1 indicated that increased cadmium concentrations lowered shoots and roots biomass. Pods and seeds dry weights decreased progressively with rising cadmium concentrations. Number of seeds showed significant decrease with increasing Cd concentrations. The H2O2 foliar spray increased the yield characteristics in the Cd-stressful plants. Effectively it increases dry weight of shoots, roots, seeds and pods.

Table 1 Effects of hydrogen peroxide (H2O2 mM) on shoots, roots and seeds dry weight (g) and number of seeds of Pisum sativum L. plants grown under different concentrations of cadmium (Cd)
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Photosynthetic pigments

Content of chlorophylls (a and b) was declined gradually with rising cadmium concentrations (Table 2). Cadmium at the concentrations 0.500 and 1 mM diminished considerably the content of the carotenoids in comparison with control.

Table 2 Effects of hydrogen peroxide (H2O2 mM) in chlorophylls (Chl a and b) and carotenoids amounts (mg g−1 FW) of Pisum sativum L. plants grown under different concentrations of cadmium (Cd)
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However, the H2O2 foliar treatment could decrease the negative influence of imposed Cd on photosynthetic pigments. Supplementation with H2O2 increased Chlorophylls a, b and carotenoids content at Cd-stressed plants over cadmium concentration range from 0.250 to 1 mM Cd but decreased its contents in Cd-unstressed (0 mM) and low stressed plants (0.125 mM Cd).

Soluble sugars

Cadmium stress enhanced soluble sugars content in shoots but reduced the contents in roots (Table 3). Treatment with H2O2 reduced the contents of soluble sugars in roots of Cd-stressed and unstressed plants. Shoots showed similar response at Cd concentration of 0.250 and 0.500 mM Cd and opposite response was found in unstressed (0 Cd) and highly stressed (1 mM Cd) plants. On the other hand H2O2 foliar application increased soluble sugars content in shoots, especially at higher Cd concentrations (0.5 and 1.00 mM).

Table 3 Effects of H2O2 (mM) on soluble metabolites amounts (mg g−1 DW) in both shoots and roots of Pisum sativum L. plants grown under different concentrations of cadmium (Cd)
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Soluble proteins and total free amino acids

Soluble proteins amounts in roots and shoots decreased progressively during increasing cadmium concentration (Table 3). Total free amino acids content showed a similar response in roots but opposite trend was found in shoots where shoots of Cd-stressed plant had higher total amino acids contents than plants without Cd. Foliar spraying with H2O2 increased soluble proteins content in shoots of Cd unstressed and stressed plants. In roots, the same response was noticed at higher Cd concentrations (0.500 and 1 mM Cd), however, in Cd free plants or those received low Cd concentrations (0–0.250 mM Cd) soluble proteins was lower than those not supplemented with H2O2.

In the existence or deficiency of Cd, amino acids contents in each of shoots or roots showed low concentrations in plant sprayed with H2O2 (Cd-unstressed and Cd stressed plants at 0.500 mM were exceptions).

Ascorbic acid, hydrogen peroxide and MDA

Data in Table 4 revealed cumulative amounts of ascorbic acid and as well as peroxidized lipids in roots and shoots of growing pea plants in response to Cd exposure. Lower concentration of Cd2+, decreased hydrogen peroxide content in shoots, whereas the higher Cd levels (0.500 and 1 mM cadmium) increased the content. In roots, hydrogen peroxide content increased gradually with increasing cadmium concentration.

Table 4 Effects of hydrogen peroxide (H2O2 mM) on proline, ascorbic acid, malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents (µmol g−1 FW) of both shoots and roots in Pisum sativum L. plants grown in different concentrations of cadmium (Cd)
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Foliar supplementation of H2O2 increased ascorbic acid content in the shoots. In roots low (1 mM) H2O2 concentration decreased ascorbic acid content but the concentration of 2 mM H2O2 induced slightly increase in ascorbic acid content in Cd-supplied plants. Two used H2O2 concentrations decreased malondialdehyde (M DA) content in roots and shoots of Cd-untreated as well as treated plants, except for shoot in Cd untreated plants. In shoots, MDA content was increased with elevation of Cd concentration (compared to control). H2O2 application (1 mM and 2 mM) decreased the concentration of MDA contents especially at high Cd concentration (compared to their controls at each H2O2 treatment). Furthermore, the content of MDA was suppressed in roots treated with H2O2 (1 mM and 2 mM) compared to their controls (at each Cd level).

Hydrogen peroxide content (Table 4) enhanced as a result of H2O2 treatment within roots of plants without Cd as well as in Cd applied plants. In shoots, its content increased at Cd concentrations 0, 0.125 and 0.250 m M Cd and down-regulated at higher Cd levels.

Proline

Proline content (Table 4) decreased gradually with increasing Cd concentration in both shoots and roots. The foliar supplementation with H2O2 increased proline contents in shoots of Cd treated plants over Cd concentration range from 0.250 to 1 mM. Opposite response was observed in roots at 0.125 and 0.25 mM Cd for both H2O2 concentrations used.

Role of Cd and H2O2 in plant stress and their interactions

Statistical analysis present in Table 5 indicated that the effects of cadmium (Cd), hydrogen peroxide, (H2O2) and the interaction (Cd × H2O2) were significant for most variables tested as indicated by F values. Further analysis of data through computation of the coefficient of determination (η2) that represented the proportional share of (Cd), (H2O2) and (Cd × H2O2) on the total influence of treatment combination (Table 5) signified to those: (1) Cadmium was predominant in affecting shoots and roots dry weights, fruit (pods) dry weight, shoot soluble proteins, Chl a and carotenoids. (2) Hydrogen peroxide had dominant effects on roots TAA, SP and SS and number of seeds. (3) The share of interaction (Cd × H2O2) was dominant in affecting shoots TAA and SS and shoots and roots proline, ascorbic acid, H2O2 and Chl b content. (4) Cd and Cd × H2O2 interaction had equal dominant share in affecting MAD contents in shoots and roots. (5) Cd, H2O2 and the interaction (Cd × H2O2) seem to play duality share in their subordinate influence.

Table 5 F and η2 estimates for the effects of hydrogen peroxide (H2O2), cadmium (Cd) and their interactions (H2O2 × Cd) on leaves pigments (Chl a, Chl b, and Carotenoids), fruits dry weight, number of seeds and contents of dry weight, malondialdehyde (MDA), hydrogen peroxide (H2O2), ascorbic acid, TAA, SP, proline and SS of both shoots and roots of Pisum sativum L. plants
Full size table

Discussion

Plants perform several mechanisms to compete against the adverse effects of pollution. These mechanisms may be enhanced by the addition of chemicals to plants (Gadallah 1995). Adaptation of Pisum sativum plants to toxic effect of Cd as expressed in various metabolic changes and growth improvement was enhanced by exogenously added H2O2. Generally, the H2O2 applied as foliar spray affected positively the growth and yield aspects in the cadmium suffered plants. This positive effect could be attributed to an increased in photosynthetic pigments.

Hydrogen peroxide treatment mitigates the injuries of the several abiotic stressors like cadmium stressor in rice (Bai et al. 2011; Hu et al. 2009). Guzel and Terzi (2013) reported that hydrogen peroxide increases water content, growth, mineral concentration, total sugar content, soluble protein and proline content compared to their relative (H2O2 free) sets in young maize plants.

In our work, H2O2 supplying increased photosynthetic pigments that permitted high photosynthetic activities and increased shoots dry matter content (Khandaker et al. 2012). In addition, the lower H2O2 accumulation induced by the H2O2 supplementation at higher Cd concentration is evidence that plants of Pisum sativum could regulate oxidative injuries generated by ROS in the photosynthetic apparatus and retain leaf gas exchange (Gondium et al. 2013). The prevented chlorophyll degradation due to H2O2 addition may be assigned to retain lower hydrogen peroxide content and higher leaf relative water content in leaves under abiotic stresses (Chakraborty et al. 2012; Gondium et al. 2013; Khan et al. 2017).

Though, accurate metabolism of the defensive action of H2O2 treatment at low doses against different stressors particularly Cd stress is still un-interpreted.

Generally, Pisum sativum plants supplemented with H2O2 had low contents of soluble sugars in their shoots and roots could be due to the enhancement of sugars utilization for the formation of new cells and tissues.

Data of present study indicated that cadmium-induced loss of soluble protein and stimulation of amino acids accumulation disappeared when the Pisum sativum plants were treated with H2O2 could be due to decrease oxidative stress of proteins by H2O2, retaining of the structure of proteins or/and an increased protein synthesis.

Supplementation of H2O2 increased proline contents in the tissues of cadmium stressed pea. Together, our data and results of Yang et al. (2009) showed that external H2O2 application caused a significant accumulation of proline in radicles and coleoptiles of maize seedlings. Proline accumulation recognized as a monitor of a biotic stress and regarded as essential protecting agent (Gadallah 1999). This increase in this amino acid content could be due to: (a) an increment in proline biosynthesis (Charest and Phan 1990), (b) a reduction in proline degradation, (c) the induction of a proline-producing enzyme and the inhibition of the catabolic enzyme proline oxidase (Nayyar 2003) and (d) a decrease in proline utilization.

These increment in proline content might possibly due to its several functions i.e. redox-regulation, osmo-regulation, protection against damage by ROS and metal chelation (Guzel and Terzi 2013). Hyat et al. (2013) reported that the foliar treatment of Cicer arietinum with proline caused the mitigation of the negative effects initiated by cadmium introduction. Accordingly, our data pointed to the inducement of ROS scavenging bio components e.g. proline in pea plants treated by hydrogen peroxide under cadmium stress.

Several studies showed that the addition of H2O2 at low doses might benefit plant resistance to heavy metal exposure (Bai et al. 2011; Gondim et al. 2010; Hu et al. 2009; Lin et al. 2004, 2012; Xu et al. 2011). The enhanced tolerance towards metallic stress might due to stimulated antioxidant defence mechanism following treatment by H2O2 in rice plants (Bai et al. 2011; Hu et al. 2009).

Amongst all undesirable effects stimulated by cadmium, malondialdehyde formation is the most detrimental as it can imply to cell membrane deterioration (Nazar et al. 2012). In this study malondialdehyde (MDA) significantly increased after treatment with Cd. Similar upward trend in MDA was indicated in cotton suffered from Cd toxicity (Khan et al. 2013). Conversely, H2O2 application induced downward regulation in MDA contents in shoots and roots in cadmium-treated Pisum sativum plants compared to their controls at each Cd level. The high content of malondialdehyde and increasing activity of antioxidant enzymes is an ideal detector in determining cadmium tolerance in Fragaria x ananassa plant (Muradoglu et al. 2015).

Endogenous hydrogen peroxide content raised in response to H2O2 treatment at roots of pea plants (without Cd as well as in Cd-exposed plants) and in shoots (in plants exposed to low Cd concentrations) that was in agreement with results of Xu et al. (2011). Terzi et al. (2014) found that endogenic hydrogen peroxide concentration lightly increased in hydrogen peroxide pretreated seedlings comparing to H2O2 free. This increase resulted from permeation of externally applied H2O2 to maize leaves. On the other hand, H2O2 application decreased H2O2 content at elevated Cd concentration (compared to their H2O2 sprayed controls at 1 mM and 2 mM) in pea shoot. Hasanuzzaman et al. (2017) and Hossain et al. (2015) noticed that hydrogen peroxide treatment mitigates Cd-induced oxidative stress via regulation of the antioxidant protective and glyoxalase mechanism in Brassica napus L. They concluded that the increment of both the enzymatic and non-enzymatic antioxidants benefit in decrement the oxidative injury as cleared by reduced amounts of MDA as well as H2O2.

Exogenous application of H2O2 improved the content of important reactive oxygen species scavenge components, GSH, AsA as well as the antioxidant enzyme activities that stimulated ROS scavenge pathway (Hasanuzzaman et al. 2017; Hossain et al. 2015). Supplementation with 2 mM H2O2 increased the contents of ascorbic acid in highly Cd-treated Pisum sativum plants that are related directly to hydrogen peroxide scavenge metabolism (Ashraf 2009; Blokhina et al. 2003; Gill and Tuteja 2010). Xu et al. (2011) noticed that hydrogen peroxide stimulated up-regulation of ascorbic acid and metabolism related to aluminum acclimation in Triticum aestivum L. plants. According to Noctor and Foyer (1998), the ascorbate able to react directly reactive oxygen species hence stimulate oxidative defense contra various stressful conditions. Furthermore, it was observed that the ascorbic acid and the alterations in ascorbate redox status are instantly related to stress acclimation in different plant species (Wang et al. 2010; Xu et al. 2011).

The present data indicated significant interactions between cadmium stress and H2O2 and their effects on the variables examined as indicated by F values. So as, in natural habitats the plants not only respond to the environmental factors as separate factors, however, also affected by their interactions. At certain cases e.g. shoots TAA, shoots SS, shoots and roots proline content, ascorbic acid, H2O2 and leaf chlorophyll b content, the relative impact of the interaction between the single factors was dominant but the role of separate factors was subsidiary or the minor one, though even significant.

Conclusions

Results illustrated that treatment with H2O2 enables Pisum sativum plant to endure the injurious effect of cadmium, causing improvement in growth, seeds and pods quality. The cadmium resistance prompted by H2O2 foliar treatment is due to decrease in endogenous MDA and H2O2 contents at higher Cd levels and enhancement of the non-enzymatic defense system (ascorbate), accumulation of proline especially in shoot and maintenance of chlorophyll content in Pisum sativum leaves. These characteristics promote oxidative protection against Cd stress and allow Pisum sativum plants to sustain increment of metabolic rates in cadmium stressful condition and ameliorate the growth. Finally, it can be concluded that H2O2 treatment in sub-lethal doses can exert an ameliorative effect and helped Pisum sativum plants to grow successfully in the areas subjected to cadmium pollution, such as in mining or smelting area.

Author contribution statement

SS and MG have a same contribution towards experiment design, attainment of data, analysis and performance data and prearranging of the manuscript. The ultimate manuscript was read and established via SS and MG.