Context or problem

Weed composition and diversity responses to fertilization, and the effects of weed-crop competition on crop yield are not well understood, despite the importance for designing weed management strategies in sustainable crop production.

Objective or research question

The aim of the study was to determine weed community shifts and weed-oilseed rape competition as influenced by different fertilizations.

Methods

Field investigations were conducted at the two final growing seasons of oilseed rape, after six years of different fertilization regimes, including NPK fertilization, with 180 kg N ha^-1, 60 kg P₂O₅ ha^-1 and 62 kg K ha^-1; NP fertilization, no K; NK, no P; PK, no N; and control, no fertilization. Oilseed rape yield, oilseed rape and weed species biomass and nutrient uptake, as well as weed species density and diversity were examined each growing season.

Results

Different fertilization regimes led to distinct patterns in weed community composition. NPK fertilization enhanced oilseed rape yield and growth, resulting in the lowest weed density due to intensified crop-weed competition particularly for light. Intensified crop-weed competition under high fertilization favored the dominance of a few species. In contrast, nutrient omission treatments (i.e., NP, NK, PK and control) increased the abundance of some weed species that were otherwise less competitive. The weed species Beckmannia syzigachne dominated all treatments but clearly benefited from N omission, showing the highest biomass and density under PK and control treatments. It was suppressed under NP and NPK treatments in terms of absolute biomass, but represented a greater proportion of total weed biomass than other species, indicating a higher competitive ability. A further evaluation of the relative importance of different weed species in weed-crop competition revealed that the dominant weed species Beckmannia syzigachne was the most detrimental in terms of density, biomass and nutrient uptake. In contrast, the impacts of some other species (e.g., Mazus japonicus and Ixeris polycephala) was negligible in this study.

Conclusions

Overall, the results highlighted that NPK balanced fertilization increased oilseed rape yield with improved nutrient uptake. However, the yield gain achieved did not coincide with a diverse weed community, which calls for more attention to be paid on biodiversity besides high crop yield. Suppression of targeted weed species that are competitive and dominant might be suggested to maintain weed diversity and mitigate yield loss.

中文翻译：

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六年的不同施肥制度改变了杂草群落并与冬季油菜竞争

上下文或问题

尽管在可持续作物生产中设计杂草管理策略很重要，但杂草组成和多样性对施肥的反应，以及杂草与作物竞争对作物产量的影响尚不清楚。

目标或研究问题

该研究的目的是确定受不同施肥影响的杂草群落变化和杂草-油菜竞争。

方法

在油菜的最后两个生长季节进行了田间调查，经过六年的不同施肥方案，包括 NPK 施肥，施肥量为 180 kg N ha ^-1、60 kg P ₂ O ₅ ha ^-1和 62 kg K ha ^-1 ; NP施肥，无K；NK，没有P；PK，没有N；和对照，不施肥。在每个生长季节检查油菜产量、油菜和杂草物种的生物量和养分吸收，以及杂草物种密度和多样性。

结果

不同的施肥制度导致杂草群落组成的不同模式。NPK 施肥提高了油菜的产量和生长，由于作物与杂草的竞争加剧，特别是对光的竞争，导致杂草密度最低。高施肥条件下作物与杂草竞争加剧，有利于少数物种占据优势地位。相比之下，营养素缺失处理（即 NP、NK、PK 和对照）增加了一些竞争力较弱的杂草物种的丰度。杂草品种Beckmannia syzigachne主导所有处理，但明显受益于 N 遗漏，在 PK 和对照处理下显示出最高的生物量和密度。就绝对生物量而言，它在 NP 和 NPK 处理下受到抑制，但占杂草总生物量的比例高于其他物种，表明具有更高的竞争能力。对不同杂草物种在杂草作物竞争中的相对重要性的进一步评估表明，优势杂草物种Beckmannia syzigachne在密度、生物量和养分吸收方面是最有害的。相比之下，在这项研究中，一些其他物种（例如Mazus japonicus和Ixeris polycephala）的影响可以忽略不计。

结论

总体而言，结果强调 NPK 平衡施肥提高了油菜产量，同时改善了养分吸收。然而，实现的增产与多样化的杂草群落并不一致，这需要在作物高产之外更多地关注生物多样性。可能建议抑制具有竞争力和优势的目标杂草物种，以保持杂草多样性并减轻产量损失。