The using of bio-stimulant in plants grown under stress conditions for enhancing nutrition efficiency and crop quality traits is an effective approach. One of the bio-stimulants, humus material, is defined as humic acid (HA). HA application as a promotion of plant growth to plants grown in the heavy metals-contaminated soils has promised hope in terms of effects on plants but the its limiting effect is the application dose. Therefore, the wheat seedlings were grown in hydroponic culture for 21 d and the various concentrations of humic acid (HA; 750 or 1500 mg L⁻¹) were treated alone or in combination with cadmium (Cd) stress (100 or 200 μM) for 7 d. The results showed that after Cd stress treatment, water content (RWC), osmotic potential (Ψ_Π) and chlorophyll fluorescence parameters decreased and proline content (Pro) increased for 7 d. In spite of activated peroxidase (POX) and ascorbate peroxidase (APX), stress induced the toxic levels of hydrogen peroxide (H₂O₂) accumulation. Cd stress triggered lipid peroxidation (TBARS content). HA application successfully eliminated the negative effects of stress on RWC, Ψ_Π and photosynthetic parameters. In the presence of HA under stress, the increased activation of superoxide dismutase (SOD), catalase (CAT) and NADPH-oxidase (NOX) enzymes and ascorbate, glutathione and GSH/GSSG ratio observed. Only 750 mg L⁻¹ HA under stress conditions induced the activities of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), and dehydroascorbate (DHA) content. After the combined application of HA and Cd stress, the low contents of H₂O₂ and TBARS maintained in wheat leaves. Hence, HA successfully eliminated the toxicity of Cd stress by modulating the water status, photosynthetic apparatus and antioxidant activity in wheat leaves.

在胁迫条件下生长的植物中使用生物刺激剂以提高营养效率和作物品质性状是一种有效的方法。一种生物刺激物，腐殖质，被定义为腐殖酸（HA）。在对重金属污染的土壤中生长的植物上，HA的应用促进了植物的生长，就对植物的影响而言，希望寄予希望，但其局限性是施用剂量。因此，将小麦幼苗在水培条件下生长21 d，然后分别处理各种浓度的腐殖酸（HA； 750或1500 mg L ^-1）或与镉（Cd）胁迫（100或200μM）联合处理。 7天 结果表明，镉胁迫处理后，水分（RWC），渗透势（_ΨΠ）和叶绿素荧光参数降低，脯氨酸含量（Pro）增加7 d。尽管激活了过氧化物酶（POX）和抗坏血酸过氧化物酶（APX），压力仍会导致过氧化氢（H ₂ O ₂）积累的毒性水平。镉胁迫引发脂质过氧化（TBARS含量）。HA应用成功地消除了应力对RWC，Ψ的负面影响_Π和光合参数。在存在HA的情况下，观察到超氧化物歧化酶（SOD），过氧化氢酶（CAT）和NADPH-氧化酶（NOX）酶以及抗坏血酸，谷胱甘肽和GSH / GSSG比率的增加。仅750 mg L ^-1HA在胁迫条件下诱导了单脱氢抗坏血酸还原酶（MDHAR）和脱氢抗坏血酸还原酶（DHAR）的活性，以及​​脱氢抗坏血酸（DHA）的含量。联合施用HA和Cd胁迫后，小麦叶片中的H ₂ O ₂和TBARS含量保持较低。因此，HA通过调节小麦叶片的水分状况，光合作用和抗氧化活性，成功地消除了Cd胁迫的毒性。