Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] is a problematic weed in rice (Oryza sativa L.) fields. Overapplication of herbicides causes environmental pollution and the emergence of resistant weeds, and integrated weed management methods can reduce dependence on herbicides. The growth of E. crus-galli and rice seedlings was shown to be significantly inhibited by high concentrations of fulvic acid (FA, C14H12O8) under flooding conditions (HF, 0.80 g L−1) (P < 0.05). In contrast, seedling growth was promoted by the application of very low concentrations of FA (LF, 0.02 g L−1). The activities of glutathione S-transferase (GST) and antioxidant enzymes, including total superoxide dismutase (T-SOD), peroxidase (POD), and catalase (CAT), in E. crus-galli seedlings were enhanced by the LF treatment; while POD activity decreased and GST, T-SOD, and CAT activity was not significantly altered by the HF treatment. The metabolomic and transcriptomic analyses showed that FA regulated E. crus-galli seedling growth by affecting the synthesis of indole derivatives and flavonoid compounds. Compared with the blank control (CK, 0 g L−1), the levels of four indole derivatives were upregulated under the HF treatment, and the indole derivatives were slightly downregulated under the LF treatment. The flavonoids, including naringenin, naringenin chalcone, eriodictyol, kaempferol, and epigallocatechin, were downregulated under HF treatment, and the growth of E. crus-galli was reduced. In contrast, the metabolism and transcription of flavonoids were not significantly altered by the LF treatment. The addition of 0.80 g L−1 FA obviously inhibited the growth of newly sprouted E. crus-galli, whereas rice growth was significantly promoted 8 d after rice planting (P < 0.05). The application of FA, therefore, might be a potential integrated weed management method to control the damage caused by E. crus-galli in paddy fields.

中文翻译：

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黄腐酸对淹水条件下稗草（Echinochloa crus-galli）幼苗生长的影响

稗草 [稗草(L.) P. Beauv.] 是水稻中的一种有问题的杂草（水稻L.) 字段。除草剂的过度使用会导致环境污染和抗性杂草的出现，综合杂草管理方法可以减少对除草剂的依赖。的成长E. crus-galli高浓度黄腐酸（FA、C14H12○8) 在洪水条件下 (HF, 0.80 g L-1) (P < 0.05)。相反，通过施用极低浓度的 FA（LF，0.02 g L-1）。谷胱甘肽的活动小号-转移酶 (GST) 和抗氧化酶，包括总超氧化物歧化酶 (T-SOD)、过氧化物酶 (POD) 和过氧化氢酶 (CAT)，E. crus-galliLF处理增强了幼苗；而 POD 活性降低，而 GST、T-SOD 和 CAT 活性未因 HF 处理而显着改变。代谢组学和转录组学分析表明，FA 调节E. crus-galli通过影响吲哚衍生物和黄酮类化合物的合成来促进幼苗生长。与空白对照 (CK, 0 g L-1），四种吲哚衍生物的水平在HF处理下上调，而吲哚衍生物在LF处理下略有下调。黄酮类化合物，包括柚皮素、柚皮素查尔酮、圣草酚、山柰酚和表没食子儿茶素，在 HF 处理下被下调，并且E. crus-galli被减少了。相反，LF 处理没有显着改变黄酮类化合物的代谢和转录。添加 0.80 g L-1FA明显抑制新芽的生长E. crus-galli, 而水稻种植 8 d 后水稻生长显着促进（P < 0.05）。因此，FA 的应用可能是一种潜在的综合杂草管理方法，以控制由E. crus-galli在稻田里。