# Straw Mulching Differentially Shapes the Structure and Function of Below‐Ground Bacterial Communities in Potato Depending on eDNA Source and Cultivar

## TL;DR

Straw mulching changes soil bacteria in potato plants, affecting different parts of the plant and depending on the potato variety.

## Contribution

The study reveals cultivar-specific and sample-type-dependent effects of straw mulching on bacterial communities and tuber quality in potato.

## Key findings

- Straw mulching increased bacterial richness and altered community structure in potato-associated samples.
- Copiotrophic genera like Pseudomonas were enriched in mulched rhizosphere, root, and tuber peel.
- Straw mulching's impact on bacterial communities and tuber quality was found to be cultivar-dependent.

## Abstract

Potato is the world's third most important food crop, yet its production relies heavily on pesticides, creating a need for sustainable alternatives. We assessed how straw mulching, a practice known to improve soil fertility, enrich microbial activity, and suppress diseases, affects below‐ground bacterial community structure and functional potential across different potato‐associated sample types. A field experiment was conducted in northern Sweden using two potato cultivars under mulched and control soil conditions. Samples from the rhizosphere, root, soil, and tuber peel were analyzed using 16S ribosomal RNA (rRNA) gene sequencing (Illumina platform) to assess bacterial diversity and community composition. Straw mulching significantly increased bacterial richness and altered community structure across sample types and cultivars. Copiotrophic genera, which thrive in nutrient‐rich environments, included Rhodanobacter, Mucilaginibacter, Flavobacterium, and Pseudomonas, and were enriched in rhizosphere, root, and tuber peel. Oligotrophs such as Bryobacter and Candidatus Solibacter dominated the soil and are known to contribute to organic matter turnover and plant growth. Notably, in the peel of one cultivar (King Edward), the abundance of Pseudomonas increased 5–7‐fold, correlating with elevated starch and ascorbic acid contents of the tubers. In conclusion, the effect of straw mulching on soil bacterial communities and tuber quality appears to be diverse and cultivar dependent. Long‐term and large‐scale studies are needed to evaluate cumulative impacts on soil health, yield, and resilience.