Background and aims

Drought and heavy metals (HMs) stress significantly impact maize (Zea mays L.), which is crucial for global food security. The aim of this study was to evaluate the effectiveness of sodium nitroprusside (SNP) and melatonin (MT) in alleviating the detrimental effects of drought and HMs’ stress on the growth and development of maize.

Methods

Maize plants were exposed to lead (Pb) and cadmium (Cd) under well-watered (WW), mild water stress (MWS), moderate water stress (MoWS), and severe water stress (SWS) conditions. The impact of these treatments on plant biomass, photosynthetic efficiency, antioxidant defense mechanisms, and water usage efficiency (WUE) was assessed.

Results

Drought stress dramatically reduced plant biomass; under SWS compared to WW, fresh and dry weight decreased by up to 24% and 28%, respectively. Under MWS, fresh biomass was improved by 15% in the MT group and 13% in the SNP group, respectively. Dry weight was promoted by 17% in MT and 15% in SNP respectively. Statistical analysis revealed significant differences in biomass and photosynthetic efficiency (p < 0.05). MT and SNP boosted photosynthetic efficiency, triggered antioxidant defense mechanisms, and increased WUE by 20% under MWS and 43% under SWS. Under extreme water stress, MT and SNP reduced nutrient absorption losses, especially for potassium.

Conclusions

The results suggest that MT and SNP increase biomass production, photosynthetic efficiency, antioxidant activity, and nutrient absorption in maize, thereby enhancing resilience to drought and HM stress.

中文翻译：

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使用褪黑素和硝普钠缓解玉米干旱和重金属胁迫

 背景和目标

干旱和重金属 （HMs） 胁迫对玉米 （Zea mays L.） 产生重大影响，而玉米对全球粮食安全至关重要。本研究的目的是评估硝普钠 （SNP） 和褪黑激素 （MT） 在减轻干旱和 HMs 胁迫对玉米生长发育的不利影响方面的有效性。

 方法

玉米植株在浇水充足 （WW）、轻度水分胁迫 （MWS）、中度水分胁迫 （MoWS） 和重度水分胁迫 （SWS） 条件下暴露于铅 （Pb） 和镉 （Cd）。评估了这些处理对植物生物量、光合效率、抗氧化防御机制和水利用效率 （WUE） 的影响。

 结果

干旱胁迫大大降低了植物生物量;与 WW 相比，在 SWS 下，鲜重和干重分别下降了 24% 和 28%。在 MWS 下，MT 组和 SNP 组的新鲜生物量分别提高了 15% 和 13%。MT 和 SNP 的干重分别提高了 17% 和 15%。统计分析显示生物量和光合效率存在显著差异 （p < 0.05）。MT 和 SNP 提高了光合效率，触发了抗氧化防御机制，在 MWS 下使 WUE 增加了 20%，在 SWS 下增加了 43%。在极端水分胁迫下，MT 和 SNP 减少了养分吸收损失，尤其是钾的吸收损失。

 结论

结果表明，MT 和 SNP 提高了玉米的生物量产量、光合效率、抗氧化活性和养分吸收，从而增强了对干旱和 HM 胁迫的恢复力。