Data_Sheet_1_Winter cover crop suppression methods influence on sunflower growth and rhizosphere communities.docx

Sunflower (Helianthus annuus L.), a vital crop for global vegetable oil production, encounters sustainability challenges in its cultivation. This study assesses the effects of incorporating a winter cover crop (CC), Avena sativa (L.), on the subsequent growth of sunflower crops and the vitality of their rhizosphere microbial communities over a two-year period. It examines the impact of two methods for suppressing winter CC—chemical suppression using glyphosate and mechanical suppression via rolling—both with and without the addition of phosphorus (P) starter fertilizer. These approaches are evaluated in comparison to the regional best management practices for sunflower cultivation, which involve a preparatory chemical fallow period and the subsequent application of starter P fertilizer. The methodology utilized Illumina sequencing for the analysis of rhizosphere bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) amplicons. Findings indicate a significant improvement (9–37%) in sunflower growth parameters (plant height, stem diameter, head diameter, and head dry weight) when cultivated after glyphosate-suppressed winter CC compared to the chemical fallows. Conversely, rolling of winter CC generally negatively affected sunflower growth. Rhizosphere bacterial communities following chemical suppression of winter CC showed greater Pielou’s evenness, indicating a uniform distribution of species. In general, this treatment had more detrimental effects on beneficial sunflower rhizosphere bacteria such as Hymenobacter and Pseudarthrobacter than rolling of the winter CC, suggesting that the overall effect on sunflower growth may be mitigated by the redundancy within the bacterial community. As for fungal diversity, measured by the Chao-1 index, it increased in sunflowers planted after winter CC and receiving P fertilization, underscoring nutrient management’s role in microbial community structure. Significant positive correlations between fungal diversity and sunflower growth parameters at the reproductive stage were observed (r = 0.41–0.72; p

向日葵（Helianthus annuus L.），作为全球食用油生产的重要作物，其种植过程中面临着可持续发展的挑战。本研究评估了在两年期间，将越冬覆盖作物（CC）燕麦（Avena sativa L.）的引入对后续向日葵作物生长及其根际微生物群落活力的影响。研究探讨了两种抑制越冬CC的方法——使用草甘膦进行化学抑制和通过碾压进行机械抑制，并考察了在添加磷（P）基肥与否的条件下，这两种方法与当地最佳向日葵种植管理实践（包括预备化学休闲期和随后的基肥P应用）的比较。该研究采用Illumina测序技术，对根际细菌16S rRNA基因和真菌内转录间隔区（ITS）扩增子进行分析。结果显示，与化学休闲相比，在草甘膦抑制的越冬CC之后种植的向日葵在生长参数（植株高度、茎直径、头直径和头干重）方面有显著提升（9–37%）。相反，越冬CC的碾压通常对向日葵生长产生负面影响。经过化学抑制的越冬CC后的根际细菌群落显示出更高的Pielou均匀度，表明物种分布均匀。总体而言，这种处理对有益于向日葵的根际细菌，如Hymenobacter和Pseudarthrobacter，比碾压越冬CC有更大的负面影响，这表明细菌群落中的冗余可能减轻对向日葵生长的整体影响。至于真菌多样性，通过Chao-1指数衡量，在冬季CC后种植并接受磷肥的向日葵中有所增加，凸显了养分管理在微生物群落结构中的作用。在生殖阶段，观察到真菌多样性与向日葵生长参数之间存在显著的正相关（r=0.41–0.72；p<0.05）。