Background and aims

Weeds are a major biotic stressor impacting crop production. Improving the competitiveness of wheat (Triticum aestivum L.) could provide a useful tool in integrated weed management. While wheat typically exhibits conservative early growth, early vigour has been increased through long-term recurrent selection for greater early biomass and leaf area. However, the influence of integrating such vigour into breeding lines for improving competitive ability remains to be explored.

Methods

In replicated controlled environment experiments, the effect of breeding early shoot vigour on root development and below-ground competitiveness was carefully examined. Physical and chemical characteristics of wheat vigour lines were assessed and compared with commercial cultivars in hydroponics and field soil experiments. Measurements included early root growth, rhizosheath size and growth responses in the presence of annual ryegrass, a major weed in wheat production.

Results

The vigorous lines exhibited larger leaf widths, increased cell file number, increased total root length and larger rhizosheaths compared with commercial parents. Numerous secondary metabolites with known allelopathic effects on weeds were detected in the roots and the rhizosphere, and significant allelochemical level differences observed between distilled water and soil water extract-treated plants. Although the vigour lines were significantly more competitive than the commercial cultivars against ryegrass, they produced similar levels of phytotoxic secondary metabolites.

Conclusion

Competition below-ground was strongly suppressive of ryegrass for the more vigorous genotypes suggesting that breeding with shoot vigour had pleiotropic effects on key root traits for below-ground wheat competitiveness.

中文翻译：

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小麦早期芽活力的渗入可以改变根系，提高竞争力，并为综合杂草管理提供选择

背景和目标

杂草是影响作物生产的主要生物应激源。提高小麦（ Triticum aestivum L.）的竞争力可以为综合杂草治理提供有用的工具。虽然小麦通常表现出保守的早期生长，但通过长期循环选择以获得更大的早期生物量和叶面积，早期活力得到了提高。然而，将这种活力整合到育种系中对提高竞争能力的影响仍有待探索。

方法

在重复的受控环境实验中，仔细检查了培育早期枝条活力对根系发育和地下竞争力的影响。在水培和田间土壤实验中评估了小麦活力系的物理和化学特性，并与商业品种进行了比较。测量包括早期根部生长、根鞘大小以及一年生黑麦草（小麦生产中的主要杂草）存在下的生长反应。

结果

与商业亲本相比，活力品系表现出更大的叶宽、增加的细胞档案数量、增加的总根长度和更大的根鞘。在根和根际中检测到许多对杂草具有已知化感作用的次生代谢物，并且在蒸馏水和土壤水提取物处理的植物之间观察到显着的化感化学水平差异。尽管活力品系比商业品种对黑麦草的竞争力明显更强，但它们产生了相似水平的植物毒性次生代谢产物。

结论

地下竞争强烈抑制黑麦草的更旺盛的基因型，这表明具有芽活力的育种对地下小麦竞争力的关键根性状具有多效性影响。