Sonchus oleraceus and Rapistrum rugosum are two rapidly emerging weeds of the northern grain region of Australia. To understand the ability of these weeds regarding their germination response to temperature and different soil moisture regimes, experiments were undertaken on the germination of these weeds at varying osmotic potential and temperature regimes. The experiment was conducted as a split-plot design with alternating day/night temperature regimes (15/5, 20/10, 25/15 and 30/20 degrees C) as a main plot and osmotic potential regimes (0.0, -0.1, -0.2, -0.4, -0.6, -0.8 and -1 MPa) as a subplot. At different temperature regimes, there was 65-91% germination of S. oleraceus in water (0 MPa). There was 0-4% germination at -0.8 MPa and no germination at -1.0 MPa. Osmotic potential values that can cause 50% reduction in germination of S. oleraceus based on a sigmoid regression model ranged from -0.38 to -0.48 MPa. There was 33-81% germination of R. rugosum in distilled water (0 MPa), 1-3% germination at -0.8 MPa and no germination at -1.0 MPa. Osmotic potential values that can cause 50% reduction in germination of R. rugosum based on a sigmoid model ranged from -0.26 to -0.54 MPa. Results of the study were related to the emergence pattern of weeds during field survey and soil moisture profiles estimated by the Australian Landscape Water Balance Model and explain the emergence of these weeds outside the normal seasonal window of prevalence as a response to changes in weather.

中文翻译：

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Sonchus oleraceus 和 Rapistrum rugosum 对不同温度和水分胁迫情况的萌发和萌发响应

Sonchus oleraceus 和 Rapistrum rugosum 是澳大利亚北部谷物区的两种快速出现的杂草。为了了解这些杂草对温度和不同土壤湿度状况的萌发响应能力，对这些杂草在不同渗透势和温度状况下的萌发进行了实验。实验作为裂区设计进行，以交替的日/夜温度范围（15/5、20/10、25/15 和 30/20 摄氏度）作为主区和渗透势范围（0.0、-0.1、 -0.2、-0.4、-0.6、-0.8 和 -1 MPa）作为子图。在不同的温度条件下，S. oleraceus 在水 (0 MPa) 中的发芽率为 65-91%。-0.8 MPa 时有 0-4% 的发芽，-1.0 MPa 时没有发芽。可能导致 S. 发芽率降低 50% 的渗透势值。基于 sigmoid 回归模型的 oleraceus 范围从 -0.38 到 -0.48 MPa。R. rugosum 在蒸馏水 (0 MPa) 中有 33-81% 的发芽率，-0.8 MPa 下有 1-3% 发芽率，-1.0 MPa 下没有发芽率。基于 sigmoid 模型，可导致 R. rugosum 发芽减少 50% 的渗透势值范围从 -0.26 到 -0.54 MPa。研究结果与田间调查期间杂草的出现模式和澳大利亚景观水平衡模型估计的土壤水分剖面有关，并解释了这些杂草在正常季节流行窗口之外的出现是对天气变化的反应。基于 sigmoid 模型，可导致 R. rugosum 发芽减少 50% 的渗透势值范围从 -0.26 到 -0.54 MPa。研究结果与田间调查期间杂草的出现模式和澳大利亚景观水平衡模型估计的土壤水分剖面有关，并解释了这些杂草在正常季节流行窗口之外的出现是对天气变化的反应。基于 sigmoid 模型，可导致 R. rugosum 发芽减少 50% 的渗透势值范围从 -0.26 到 -0.54 MPa。研究结果与田间调查期间杂草的出现模式和澳大利亚景观水平衡模型估计的土壤水分剖面有关，并解释了这些杂草在正常季节流行窗口之外的出现是对天气变化的反应。