意大利苍耳的化感作用对乌拉尔甘草种子萌发和幼苗生长的影响

Effects of allelopathy of Xanthium italicum on seed germination and seedling growth of Glycyrrhiza uralensis

入侵植物意大利苍耳已经开始入侵乌拉尔甘草田,研究其化感物质对乌拉尔甘草的萌发和生长的影响,对意大利苍耳入侵乌拉尔甘草田的能力及后果评估具有重要的参考意义。故本试验采用培养皿法,分析了浓度分别为0、25、50、75、100 g·L^(-1)意大利苍耳的根、茎、叶和果实水浸提液处理下乌拉尔甘草的种子萌发和幼苗生长的差异。采用盆栽法分别模拟三种水平的意大利苍耳各部分器官的凋落物,以研究其对乌拉尔甘草的抗氧化酶系统的影响。结果表明:意大利苍耳的根、叶和果实水浸提液均对乌拉尔甘草的种子萌发存在不同程度的化感抑制作用,其中叶水浸提液抑制作用最强,浓度为25、50、75、100 g·L^(-1)的叶水浸提液处理下,与对照相比其种子萌发率分别降低了19.51%、43.9%、56.1%和69.51%。意大利苍耳的叶和果实水浸提液均能够显著抑制乌拉尔甘草幼苗生长,在浓度为100g·L^(-1)的意大利苍耳叶和果实水浸提液处理下,乌拉尔甘草幼苗的茎长分别是对照组的34.91%和30.18%,其幼苗鲜重分别是对照组的13.33%和27.62%,根和茎水浸提液在高浓度时(75 g·L^(-1)和100 g·L^(-1))显著抑制乌拉尔甘草幼苗的生长。意大利苍耳各器官对乌拉尔甘草的化感综合效应指数(SE)均小于0。意大利苍耳各器官粉末对乌拉尔甘草抗氧化酶活性表现为,随着土壤中意大利苍耳根和茎的粉末含量的增加,乌拉尔甘草的SOD、POD和CAT活性逐渐增加,而随着土壤中意大利苍耳叶和果实粉末的含量增加,3种酶的活性则表现出先升高再降低的趋势。研究结果证实,入侵植物意大利苍耳对乌拉尔甘草具有很强的化感抑制效应。

Xanthium italicum Moretti has been invading farmland of Glycyrrhiza uralensis Fisch, and the study of the effects of its allelochemicals on the germination and growth of G. uralensis has important experimental evidence forevaluating the invasibility and effect of X. italicum on the G. uralensis population in farmland. Therefore, we used petri dish method to analyze the differences of seed germination and seedling growth of G. uralensis treated with water extracts of roots, stems, leaves and fruits at concentrations of 0, 25, 50, 75 and 100 g·L^(-1), and we used the pot method to simulate the litter of each part of the organ of X. italicum in three levels to study the effect of X. italicum on the antioxidant enzyme system of G. uralensis. It was found that: The extracts of roots, leaves and fruits of X. italicum all have different intensities of allelopathic inhibitory effects on the seed germination of G. uralensis. Among them, the leaf aqueous extract has the strongest inhibitory effect, compared with the control, the seed germination rate of 25,50,75 g·L^(-1) and 100 g·L^(-1) leaf extracts treatments were reduced by 19.51%, 43.9%, 56.1% and 69.51%, respectively. While the leaves and fruits aqueous extracts can significantly inhibit the seedlings growth of G. uralensis at various concentration. Under the treatment of the aqueous extract of the leaves and fruits of the X. italicum at a concentration of 100 g·L^(-1), the stem length of the seedlings of G. uralensis were 34.91% and 30.18% of the control group, and the fresh weight of the seedlings was 13.33% and 27.62% of the control group, respectively. And root and stem aqueous extract significantly inhibited the growth of G. uralensis seedlings at high concentrations(75 g·L^(-1) and 100 g·L^(-1)). The SE values of each organ of X. italicum to G. uralensis were all less than 0. Allelopathic substances in various organs of X. italicum have effects on the antioxidant enzyme activities of G. uralensis, the increase of the powder content of the roots and stems of X. italicum in the soil promoted the SOD, POD and CAT activities of G. uralensis. When the content of the leaves and fruits powder in the soil increased, the three protective enzymes activity showed a trend of first increased and then decreased. The results of the study confirmed that the invasive plant X. italicum has a strong allelopathic inhibitory on G. uralensis.