I have read the manuscript by Ciocca et al. with interest as it spans two very different areas of research. The approach is original and provides interesting results (at least at this stage) in improved root growth.
A clear weakness of the paper for me, which I believe should be addressed before publication, is the fact that no mechanistic insight is given. The conclusions provide a hand-wavy discussion, but it is not supported by experimental evidence. Establishing a clear electron transfer mechanism is really a must to bring this area forward as others will be able to work with the information to provide enhanced materials in the future. I understand that this requires significant additional work, but for a ‘first’ in the area this really needed, in particular in complex systems, such as plants.
I have a few other comments below, but all of these are fairly minor in comparison:
1. Other hybrid systems, for example conjugated polymers with bacteria in the context of increasing their activity should be discussed in the introduction.
2. How was the P3HT sample made? Characterization data, i.e. energy levels and GPC data should be presented as a minimum for the material.
3. Where the NPs characterised following autoclave? Where their properties comparable to the as made NPs?
4. Another minor point: The authors state that “(ii) in contrast, intense red spots, measuring less than 1 µm in diameter, were observed exclusively in the leaves of the plants grown in the P3HT-NPs supplemented medium. This indicates the presence of P3HT-NPs in the leaf”. I do not think that it can be said with confidence that the polymer is in the form of nanoparticles in the leaves. These could also be partially aggregated in the leaf, the measurement does not provide size information on the relevant scale.
5. Whenever working with polymers, microplastics will be a concern. How has the impact of this been assessed in future applications? Using carbon dots would appear to be a safer option. A discussion of this would be useful for the reader.
6. According to IUPAC “sulphate” should be spelled as “sulfate”.
7. Chemical formulae like CO2 should not be italicised.

The authors have done a good job in addressing my comments. Smaller minor issues remain (e.g. GPC), but these should not hold back the manuscript from publication.