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Abbreviations are as follows: 
iteration (I), short-read subsample size (Size), and subsampling rate (Rate);
the short-read polishing preparation time (Tp),
the memory required for short-read polishing preparation (Mp),
the short-read polishing time (Ts),
the memory required for short-read polishing (Ms),
the final plastid genome assembly length (Length), and
the percent identity of a pairwise alignment with one from the previous step (Pident).

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