ABSTRACT

In this study, the effects of fulvic acid (FA) were investigated on the concentrations of photosynthetic pigments, malondialdehyde (MDA) and root and stem anatomy in Triticum aestivum L. under chromium stress. Plants were grown under-controlled growth chamber conditions and then exposed to 0.10, 0.20, 0.30 or 0.50 mM chromium solution (Cr⁶⁺) and 1.5 mg/L of FA solution alone or in combination with the Cr stress for 21 days. Results indicate that the chlorophyll a, chlorophyll b, total chlorophyll and carotenoid contents were lower in the chromium-treated group than in the FA + Cr treated group, depending on the amount of chromium stress applied. The decrease levels in the ratio of the photosynthetic pigments in Cr treated groups were as follows (%): Chlorophyll a 55, chlorophyll b 72.83, total chlorophyll 44.65, total carotenoid 45.09. These levels in FA + Cr treated groups were as follows, respectively: 28.82, 53.70, 31.21 and 31.35. On the other hand, the chlorophyll a/b ratio and MDA contents were higher in the chromium-treated group in comparison to the FA + Cr treated group. The increase levels in Cr treated groups in the ratio of the chlorophyll a/b and MDA contents were as follows (%): Chlorophyll a/b 40.17, MDA 45.95. The ameliorating effect of FA was determined as 5.40% in MDA and 4.78% in chlorophyll a/b ratio. The cross-sections of plant roots exposed to Cr stress presented some anatomical changes. The stem of Cr-treated plants showed an increase in the thickness of sclerenchyma, phloem and xylem and the diameter of parenchyma cells. Significant reduction in the diameter of vessel elements in the stem were observed as a result of Cr exposure. In conclusion, FA could play an important role in reducing chromium stress in wheat plants.

摘要

在这项研究中，研究了富里酸 (FA) 对铬胁迫下普通小麦中光合色素、丙二醛 (MDA) 浓度以及根和茎解剖结构的影响。植物在受控生长室条件下生长，然后暴露于 0.10、0.20、0.30 或 0.50 mM 铬溶液 (Cr ⁶⁺ ) 和 1.5 mg/L FA 溶液，单独或与 Cr 胁迫相结合，持续 21 天。结果表明，叶绿素a、叶绿素b，铬处理组的总叶绿素和类胡萝卜素含量低于 FA + Cr 处理组，这取决于施加的铬应力的量。Cr处理组光合色素比例的降低水平如下（%）：叶绿素a 55，叶绿素b 72.83，总叶绿素44.65，总类胡萝卜素45.09。FA + Cr 处理组中的这些水平分别如下：28.82、53.70、31.21 和 31.35。另一方面，与 FA + Cr 处理组相比，铬处理组的叶绿素a/b比和 MDA 含量更高。Cr处理组叶绿素a/b比值和MDA含量增加水平如下（%）：a/b 40.17，MDA 45.95。FA 的改善作用被确定为在 MDA 中为 5.40%，在叶绿素a/b比率中为4.78% 。暴露于Cr胁迫下的植物根部的横截面呈现出一些解剖学变化。Cr处理植物的茎表现出厚壁组织、韧皮部和木质部的厚度和薄壁组织细胞的直径增加。由于铬暴露，观察到茎中血管元素的直径显着减小。总之，FA 可以在减少小麦植株铬胁迫方面发挥重要作用。