The potential of oilseed rape to suppress weed growth while maintaining optimal yield and quality is not well understood under field conditions in Australia. This study, conducted in Condobolin and Wagga Wagga, New South Wales (NSW), during 2015 and 2016, examined a diverse range of commercial oilseed rape cultivars for their inherent ability to suppress weeds and maintain yields when in competition with natural weed infestations, with and without pre‐emergent herbicide treatment. Cultivar differences were observed in oilseed rape canopy architecture and yield; however, early‐season biomass, light interception, leaf area index and visual vigour ratings exhibited both year and location interactions. Cultivars with the highest biomass, light interception, leaf area indices and visual vigour were typically also the most weed‐suppressive, in particular GT‐50 and Hyola 600RR. Although crop and weed biomass accumulation differed significantly among cultivars for both location and year, weed biomass was inversely related to cultivar biomass in both years and locations. Hybrid Hyola and GT‐50 cultivars exhibited up to 50% less weed biomass while maintaining consistently high levels of dry crop biomass. In addition, pre‐emergent herbicide applications reduced weed infestation and contributed to higher crop yield in both locations and years. Given the consistent aboveground competitive ability of certain oilseed rape cultivars, our study demonstrated that diverse cultivar‐dependent competitive traits such as early growth vigour, biomass production, absorption of photosynthetically active radiation and production and retention of crop residue significantly impacted weed establishment and total weed biomass. Our findings suggest that cultivar selection offers potential as a tool for maintaining suitable grain yield in the presence of weeds while potentially delaying the development of herbicide resistance through efficacious weed suppression.

中文翻译：

---

新南威尔士州南部部分商业油菜油菜品种的早期活力，杂草抑制和产量评估

在澳大利亚的田间条件下，油籽油菜在抑制杂草生长的同时保持最佳产量和质量的潜力尚不为人所知。这项研究于2015年至2016年在新南威尔士州（CW）的Condobolin和Wagga Wagga进行，研究了各种商品油菜油菜品种在与天然杂草侵染竞争时具有抑制杂草和维持产量的固有能力，且未经芽前除草剂处理。在油菜油菜冠层结构和产量上观察到了品种差异。然而，早期的生物量，光的截留率，叶面积指数和视觉活力等级表现出年度和位置的相互作用。具有最高生物量，光拦截，叶面积指数和视觉活力的品种通常也是抑制杂草最多的品种，特别是GT-50和Hyola 600RR。尽管不同地点和年份的作物和杂草生物量积累差异显着，但杂草生物量在年份和地点均与品种生物量成反比。Hyola和GT-50杂交品种的杂草生物量减少了多达50％，同时始终保持高水平的干燥作物生物量。此外，芽前除草剂的使用减少了杂草的侵染，并促进了地点和年份的作物增产。鉴于某些油籽油菜品种具有一致的地上竞争能力，我们的研究表明，依赖于不同品种的竞争性状，例如早期生长活力，生物量生产，光合活性辐射的吸收以及作物残渣的产生和保留显着影响了杂草的形成和杂草的总生物量。我们的发现表明，在杂草存在的情况下，选择品种可以提供维持合适的谷物产量的潜力，同时通过有效抑制杂草来延缓除草剂抗性的发展。