I did a lab biology project on seed germination and the results weren't as expected. pH 5 worked better than pH 6 or 7 which seemed weird because surely it would be too acidic. I've been trying to find an explanation as to why I got these results and I think, possibly, it's to do with the buffer solutions I used. What could be in the buffer solution which might give these results.

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Thanks in advance for any help!