Hairy fleabane [Conyza bonariensis(L.) Cronquist] is a problematic weed in Australian no-till cropping systems. Consequently, a study was conducted to examine the effect of temperature, light, salt stress, osmotic stress, burial depth, and sorghum crop residue on germination and emergence in two populations (C and W: collected from chick pea [Cicer arietinumL.] and wheat [Triticum aestivumL.] fields, respectively) ofC. bonariensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C); however, the C population had optimum (and similar) germination over the range of 20/10 and 30/20 C, while the W population showed maximum germination at 25/15 C. A negative relationship was observed between osmotic potential and germination, with 31% and 14% germination of the C and W populations at -0.6 MPa, respectively. These observations suggest that population C was more tolerant to higher osmotic potentials than population W. Seeds of both populations germinated when exposed to a wide range of sodium chloride levels (NaCl, 0 to 200 mM); however, beyond 200 mM NaCl, no germination was observed in either population. Maximum germination of the C (70%) and W (41%) populations was observed on the soil surface with no emergence from a burial depth of 1 cm. The application of sorghum residue at an amount of 6,000 kg ha(-1)reduced emergence of the C and W populations by 55% and 58%, respectively, compared with the no-residue treatment. Knowledge gained from this study suggests that the following strategies could be used for more efficacious management ofC. bonariensis: (1) a shallow-tillage operation to bury weed seeds in conventional tillage systems, and (2) retention of sorghum residue on the soil surface in no-till systems.

中文翻译：

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毛蚤（Conyza bonariensis）的萌发生态及其对杂草管理的影响

毛蚤 [Conyza bonariensis (L.) Cronquist] 是澳大利亚免耕种植系统中的一种有问题的杂草。因此，进行了一项研究，以检查温度、光照、盐胁迫、渗透胁迫、埋藏深度和高粱作物残留对两个种群（C 和 W：从鹰嘴豆[Cicer arietinumL.] 和小麦 [Triticum aestivumL.] 田，分别为 C. 博纳瑞斯。两个种群都能够在大范围的昼/夜交替温度（15/5 至 35/25 C）下发芽；然而，C 种群在 20/10 和 30/20 C 范围内具有最佳（和相似）发芽，而 W 种群在 25/15 C 显示出最大发芽。在渗透势和发芽之间观察到负相关，其中C 和 W 种群在 -0 时的发芽率为 31% 和 14%。分别为 6 兆帕。这些观察结果表明，种群 C 比种群 W 更能耐受更高的渗透势。当暴露于大范围的氯化钠水平（NaCl，0 到 200 mM）时，两个种群的种子都会发芽；然而，超过 200 mM NaCl，在任何一个种群中都没有观察到发芽。在土壤表面观察到 C (70%) 和 W (41%) 种群的最大发芽率，在 1 cm 的埋藏深度没有出现。与无残留处理相比，施用 6,000 kg ha (-1) 的高粱残留物使 C 和 W 种群的出现分别减少了 55% 和 58%。从这项研究中获得的知识表明，以下策略可用于更有效地管理 C. 博纳瑞斯：