Herbicide resistance is an increasing issue in many weed species, including rigid ryegrass (Lolium rigidum Gaudin); a major weed of winter cropping systems in southern Australia. Recently, this weed has also been found in summer crops in the south eastern region of Australia. Effective control of this herbicide resistant weed across south eastern Australia requires alternative management strategies. These strategies can be informed from analyses on the interaction of germinable seeds with their regional environment and by identifying the differences between populations of varying herbicide resistance levels. In this study, we explore how various environmental factors differentially affect the seed germination and seedling emergence of three L. rigidum populations, including one glyphosate-resistant population (GR), one glyphosate-susceptible population (GS) and one population of unknown resistance status (CC04). Germination was greater than 90% for all populations at each temperature regime except 15/5 C. Populations germinated at a lower rate under 15/5 C, ranging from 74 to 87%. Salt stress had a similar effect on the germination of all populations, with 0% germination occurring at 250 mM salt stress. Population GS had greater tolerance to osmotic stress with 65% germination at −0.4 MPa compared to 47% and 43% germination for CC04 and GR, respectively; however, germination was inhibited at −0.8 and −1.6 MPa for all populations. All populations had lower germination when placed in complete darkness as opposed to alternating light/dark. Germination in darkness was lower for CC04 (69%) than GR (83%) and GS (83%). Seedling emergence declined with increasing burial depth but retained 37% emergence at 8 cm when averaged over the populations. These results indicate that L. rigidum Gaud. can survive under a range of environmental variables and the extent of survival differs based on population, however, there was no difference based on herbicide resistance status.

中文翻译：

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澳大利亚东南部硬质黑麦草（黑麦草）种群的种子萌发生态

除草剂抗性在许多杂草物种中是一个日益严重的问题，包括硬质黑麦草（黑麦草高丁）；澳大利亚南部冬季种植系统的主要杂草。最近，在澳大利亚东南部地区的夏季作物中也发现了这种杂草。在澳大利亚东南部有效控制这种抗除草剂杂草需要替代管理策略。这些策略可以通过分析可发芽种子与其区域环境的相互作用以及通过确定不同除草剂抗性水平的种群之间的差异来获得信息。在这项研究中，我们探讨了各种环境因素如何不同地影响三种植物的种子萌发和出苗。刚体乳杆菌群体，包括一个草甘膦抗性群体（GR）、一个草甘膦易感群体（GS）和一个抗性状态未知群体（CC04）。除 15/5 摄氏度外，在每个温度条件下，所有种群的发芽率均大于 90%。在 15/5 摄氏度下，种群的发芽率较低，介于 74% 至 87% 之间。盐胁迫对所有种群的萌发有类似的影响，0% 的萌发发生在 250 mM 盐胁迫下。群体 GS 对渗透胁迫的耐受性更高，在 -0.4 MPa 下发芽率为 65%，而 CCO4 和 GR 的发芽率分别为 47% 和 43%；然而，所有种群的发芽在 -0.8 和 -1.6 MPa 时受到抑制。当放置在完全黑暗的环境中时，所有种群的发芽率都低于明暗交替。CC04 (69%) 在黑暗中的发芽率低于 GR (83%) 和 GS (83%)。幼苗出苗率随着埋深的增加而下降，但在种群平均时在 8 厘米处保留了 37% 的出苗率。这些结果表明刚体乳杆菌高德。可以在一系列环境变量下生存，并且生存程度因种群而异，但是，除草剂抗性状态没有差异。