Koelreuteria integrifoliola, an important ornamental plant, has interference effect on the turf grass. However, the mechanisms of its allelopathy to plants has not been fully elucidated. Here, the allelopathic effects of leaf aqueous extract of K. integrifoliola on the growth, endogenous hormone contents and ultrastructure of Lolium perenne Lam seedlings were investigated. Leaf aqueous extract of K. integrifoliola at different concentrations (25.00, 50.00 and 100.00 mg mL⁻¹) significantly reduced the growth (in terms of dry weight), chlorophyll b, total chlorophyll and carotenoids contents of L. perenne. The results also showed the decline in indole acetic acid (IAA) and gibberellic acid (GA₃₎ contents, and the increase in abscisic acid (ABA) after extract treatment (50.00 and 100.00 mg mL⁻¹). In addition, the (IAA + GA₃)/ABA ratios in root and leaf decreased with the increase of extract concentrations. Upon exposure to extracts (50.00 and 100.00 mg mL⁻¹), L. perenne mesophyll cell showed structural abnormalities, mostly including chloroplast distribution, destruction of chloroplast membrane and thylakoid membrane, increment of plastoglobuli number, dissolution of mitochondrial membrane and disappearance of the internal ridge. Furthermore, the chloroplast number and chloroplast volume in L. perenne mesophyll cell showed a concentration-dependent decline exposed to extracts. Thus, the changes of endogenous hormones contents and their ratios, the ultrastructure changes of mesophyll cells caused by the K. integrifoliola leaf aqueous extracts are partly responsible for allelopathic inhibition of receptor plants.

Koelreuteria integrifoliola是重要的观赏植物，对草坪草有干扰作用。然而，其对植物的化感作用机制尚未完全阐明。在这里，研究了K. integrifoliola叶水提取物对黑麦草幼苗生长、内源激素含量和超微结构的化感作用。不同浓度（25.00、50.00 和100.00 mg mL ^-1）的K. integrifoliola叶水提取物显着降低了L. perenne的生长（以干重计）、叶绿素b、总叶绿素和类胡萝卜素含量。结果还显示吲哚乙酸 (IAA) 和赤霉酸 (GA) 的下降₃₎含量，以及提取物处理后脱落酸(ABA) 的增加(50.00 和100.00 mg mL ^-1 )。此外，根和叶中的(IAA + GA ₃ )/ABA比值随着提取物浓度的增加而降低。暴露于提取物（50.00 和 100.00 mg mL ^-1）后，多年生叶肉细胞显示结构异常，主要包括叶绿体分布、叶绿体膜和类囊体膜破坏、质体球数量增加、线粒体膜溶解和内部消失。岭。此外，L 中的叶绿体数量和叶绿体体积。多年生植物暴露于提取物的叶肉细胞表现出浓度依赖性下降。因此，内源性激素含量及其比例的变化，由K. integrifoliola叶水提物引起的叶肉细胞超微结构变化是对受体植物的化感抑制作用的部分原因。