Bromus diandrus Roth and Lolium rigidum Gaudin are important weeds of cereal-based cropping systems of Australian agriculture. Adaptation to environmental stresses, protracted seed germination and herbicide resistance have made these weeds serious threats to crop production.

Studies were undertaken to determine the impact of moisture stress during reproductive development on the extent of seed dormancy and the expression of genes involved with gibberellic acid and abscisic acid synthesis.

A pot study was undertaken at two locations, with two populations each of B. diandrus and L. rigidum. Water stress was applied from either the GS31 or GS60 stage until seed maturation, along with a well-watered treatment. Seeds of stressed vs well-watered treatments were assessed for seed dormancy and the expression of ABA1 and GA20ox genes using quantitative polymerase chain reaction.

The seeds from GS31 treatment, where plants experienced the longest water stress, were most dormant in both weed species. Water stress treatments altered the expression of the GA20ox gene, which was correlated with the level of dormancy in seeds of B. diandrus and L. rigidum.

This investigation has provided clear evidence of the impact of water stress on seed dormancy and on expression of genes involved in regulating seed dormancy in these weed species.

As spring rainfall in the Australian agricultural landscape is highly variable, weeds are likely to experience variable levels of water stress during reproductive development, which in turn is likely to influence seed dormancy, weed seedling emergence and effectiveness of pre-sowing weed management next season.

雀麦和黑麦草是澳大利亚农业谷物种植系统中的重要杂草。对环境胁迫的适应、种子发芽时间延长和除草剂抗性使这些杂草对作物生产构成严重威胁。

进行了研究以确定生殖发育过程中水分胁迫对种子休眠程度以及与赤霉酸和脱落酸合成有关的基因表达的影响。

在两个地点进行了盆栽研究，分别有两个种群：B.diandrus和L.rigidum。从 GS31 或 GS​​60 阶段直至种子成熟均施加水分胁迫，并进行充分浇水处理。使用定量聚合酶链反应评估胁迫处理与浇水良好处理的种子的种子休眠以及ABA1和GA20ox基因的表达。

GS31 处理后的种子在两种杂草中都处于最休眠状态，其中植物经历了最长的水分胁迫。水分胁迫处理改变了GA20ox基因的表达，这与B.diandrus和L.rigidum种子的休眠水平相关。

这项研究提供了明确的证据，证明水分胁迫对种子休眠以及参与调节这些杂草种子休眠的基因表达的影响。

由于澳大利亚农业景观的春季降雨量变化很大，杂草在生殖发育过程中可能会经历不同程度的水分胁迫，这反过来又可能影响下一季播种前杂草管理的种子休眠、杂草幼苗的出苗和有效性。