Abstract

Accumulation of non-essential heavy metals like chromium (Cr) is among major abiotic stresses, which adversely affect crop growth. Hexavalent chromium [Cr(VI)] is the most dangerous form negatively affecting the growth and productivity of crops. This study evaluated the role of black cumin extracts (BCE) in improving growth and productivity of maize genotypes under different concentrations of Cr(VI). Two maize genotypes (“Neelum” and “P1543”) were grown under 0, 4, 8 and 12 mg Cr(VI) kg⁻¹ concentrations. The BCE was applied as foliar spray at three concentrations (0, 10 and 20%) at 25 and 45 days after sowing. Increasing Cr(VI) concentration significantly (p < 0.05) reduced seed germination, root and allometric traits, gas exchange attributes and relative water contents of tested genotypes. Hybrid maize genotype better tolerated tested Cr(VI) concentrations than synthetic genotype with lower Cr accumulation and better allometric and gas exchange traits. Exogenous application of 20% BCE proved effective in lowering the adverse effects of Cr(VI) toxicity on maize genotypes. It is concluded that 20% BCE could be used to improve maize performance through better allometric and gas exchange traits under different Cr(VI) concentrations. Nonetheless, actual mechanisms involved in improved Cr(VI)-tolerance of maize with BCE application must be explored.

Novelty statement Black cumin has been widely used to reduce Cr toxicity in animals. However, the role of black cumin in reducing Cr toxicity in plants has never been studied. The present study was conducted to infer the role of different concentrations of black cumin extract in improving the growth of synthetic and hybrid maize genotypes under different levels of Cr stress. It is concluded that black cumin extract could be used to lower Cr toxicity in maize grown under Cr-contaminated soils.

摘要

非必需重金属如铬 (Cr) 的积累是主要的非生物胁迫之一，会对作物生长产生不利影响。六价铬 [Cr(VI)] 是对作物生长和生产力产生负面影响的最危险形式。本研究评估了黑孜然提取物 (BCE) 在不同 Cr(VI) 浓度下改善玉米基因型生长和生产力的作用。两种玉米基因型（“Neelum”和“P1543”）在 0、4、8 和 12 mg Cr(VI) kg ^-1浓度下生长。在播种后 25 天和 45 天，以三种浓度（0、10 和 20%）叶面喷洒 BCE。显着增加 Cr(VI) 浓度 ( p < 0.05) 降低种子发芽、根和异速生长性状、气体交换属性和测试基因型的相对含水量。与合成基因型相比，杂交玉米基因型对测试的 Cr(VI) 浓度具有更好的耐受性，具有较低的 Cr 积累和更好的异速生长和气体交换性状。外源施用 20% BCE 证明可有效降低 Cr(VI) 毒性对玉米基因型的不利影响。得出的结论是，在不同 Cr(VI) 浓度下，20% BCE 可用于通过更好的异速生长和气体交换性状来提高玉米性能。尽管如此，必须探索通过 BCE 应用提高玉米对 Cr(VI) 耐受性的实际机制。

新颖性声明黑孜然已被广泛用于降低动物的铬毒性。然而，从未研究过黑孜然在降低植物铬毒性方面的作用。本研究旨在推断不同浓度的黑孜然提取物在不同 Cr 胁迫水平下促进合成和杂交玉米基因型生长的作用。结论是，黑孜然提取物可用于降低在铬污染土壤下种植的玉米的铬毒性。