Allelopathic Effect of Lotus and Arrowhead Weed on Wheat, Wild Oat and Milkthistle Germination

ABSTRACT: An experiment was conducted to investigate the allelopathic effects of lotus (Nelumbo nucifera Gaertn.) and arrowhead (Sagittaria sagittifolia (Brummitt & Powell): L.) on seed germination of wheat and two associated weeds, namely, wild oat (Avena fatua L.) and milk thistle (Silybum marianum (L.) Gaertn.). The experiment was laid out in a Completely Randomized Design during May, 2014. Dried biomasses of lotus and arrowhead leaves were soaked in distilled water for 48 hrs for extract preparation. The extracts were applied at a rate of 5 and 10% concentrations to the seeds of wheat, wild oat and milk thistle at 25 °C in 10 cm wide Petri plates. A control treatment where only distilled water was applied to the seeds, was included for comparison. Data were recorded on germination (%), shoot length (cm), shoot and root fresh weights (g). The results revealed that 10% lotus extract reduced germination of wild oat (0.00%) and milk thistle (13.3%) but comparatively enhanced that of wheat (20%). By contrast, arrowhead totally inhibited germination of wheat and wild oat as compared to milk thistle (16.66%). Similarly, 10% lotus extract favored shoot length and root weight of wheat and milk thistle, whereas 100% inhibited wild oat. By comparison, arrowhead completely inhibited shoot length and root weight of wheat and wild oat at 10% conc. and enhanced milkthistle (3.00 cm and 3 g). A higher lotus extract conc. affected wild oat more than wheat and milkthistle, while arrowhead weed affected almost all test species. In conclusion, these aquatic weeds can be used as mulch in wheat in nearby fields of the infested aquatic water bodies for wild oat control, weed biomass disposal and nutrient addition to the soil.

摘要：本实验旨在探究莲（Nelumbo nucifera Gaertn.）与慈姑（Sagittaria sagittifolia (Brummitt & Powell): L.）对小麦及两种伴生杂草——野燕麦（Avena fatua L.）、水飞蓟（Silybum marianum (L.) Gaertn.）种子萌发的化感作用。实验于2014年5月采用完全随机设计（Completely Randomized Design）布置实施。将莲与慈姑的干燥叶片生物质置于蒸馏水中浸泡48小时以制备浸提液。以5%、10%两种浓度梯度，在25℃环境下将浸提液施加于直径10cm的培养皿（Petri plates）内的小麦、野燕麦及水飞蓟种子上。设置仅施加蒸馏水的对照组以作对照比较。实验记录的观测指标包括种子萌发率（%）、苗长（cm）、地上部鲜重及根部鲜重（g）。结果表明，10%莲浸提液可使野燕麦萌发率降至0.00%、水飞蓟萌发率降至13.3%，却可相对提升小麦萌发率至20%。与之相对，慈姑浸提液可完全抑制小麦与野燕麦的种子萌发，而对水飞蓟的萌发抑制率为16.66%。类似地，10%莲浸提液可促进小麦与水飞蓟的苗长及根部鲜重，却以100%浓度抑制了野燕麦的生长。相较而言，慈姑浸提液在10%浓度下可完全抑制小麦与野燕麦的苗长及根部鲜重，却可提升水飞蓟的对应生长指标（苗长3.00cm，鲜重3g）。更高浓度的莲浸提液对野燕麦的影响强于小麦与水飞蓟，而慈姑浸提液则几乎对所有供试物种均产生显著影响。综上，这些水生杂草可作为覆盖物应用于受污染水生水体周边的小麦田，用于防控野燕麦、处置杂草生物质并向土壤补充养分。