ABSTRACT

The utilisation of plant allelopathy is an important tool in a diversified weed management strategy. Allelochemicals are released by some plants, such as sunn hemp (Crotalaria juncea L.), to inhibit the growth of neighbouring plants. This species was tested for use as an allelopathic plant for weed control in cropping systems. The allelopathic properties of sunn hemp were tested under field conditions at different timings of 4, 8, 12 and 16 weeks after planting (WAP). The results showed that sunn hemp at 8, 12 and 16 WAP significantly decreased the total number of weeds compared with the control weedy check. The similar trend of decreasing weed number was observed in grass and broadleaf weeds, as well as sedge. The allelopathic activity of sunn hemp was further investigated in the soil planted with sunn hemp and water extracts on tested plants. Phytotoxicity of the soil, planted with sunn hemp at different timings, did not significantly decrease germination, shoot length, root length and dry weight of tested plants. However, the water extracts caused significantly decreased germination and plant growth, especially the shoot extracts exhibited the inhibitory effects more than the root extracts. Interestingly, the extracts from sunn hemp at 4 WAP had higher inhibitory effects than the extracts from other stages. These results suggest that sunn hemp growth stage is an important consideration for maximising biological weed control in cropping systems.

摘要

植物化感作用的利用是多样化杂草管理策略的重要工具。一些植物释放化感物质，例如晒麻（Crotalaria junceaL.)，抑制邻近植物的生长。该物种被测试用作化感植物以控制种植系统中的杂草。在种植后 4、8、12 和 16 周（WAP）的不同时间，在田间条件下测试了晒麻的化感特性。结果表明，与对照杂草检查相比，8、12 和 16 WAP 的 sunn 大麻显着减少了杂草总数。在草和阔叶杂草以及莎草中观察到类似的杂草数量减少趋势。在种植有晒麻和水提取物的土壤中进一步研究了晒麻的化感活性。在不同时间种植晒麻的土壤的植物毒性不会显着降低受试植物的发芽、芽长、根长和干重。然而，水提物显着降低了植物的发芽和生长，特别是芽提取物比根提取物表现出更多的抑制作用。有趣的是，4 WAP 的晒麻提取物比其他阶段的提取物具有更高的抑制作用。这些结果表明，晒麻生长阶段是最大限度地提高种植系统中生物杂草控制的重要考虑因素。