Effect of Harvest Time on Growth and Bioactive Compounds in Salvia miltiorrhiza

Danshen (Salvia miltiorrhiza) is a perennial medicinal plant belonging to the Lamiaceae family. It is adapted to a wide range of soil pH with the potential to serve as an alternative crop in the United States. To enhance its cultivation and economic viability, it is crucial to develop production practices that maximize bioactive compound yields for danshen. The objective of this study was to investigate the effects of different harvest times on plant growth and subsequent yields of bioactive components of danshen. Three harvest times were selected (60, 120, or 180 days after transplanting [DAT]). In general, plants harvested at 180 DAT had higher plant growth index (PGI), shoot number, shoot weight, root number, maximum root length, maximum root diameter, and root weight compared to plants harvested at 60 or 120 DAT. However, plants harvested at 60 or 120 DAT had higher SPAD (Soil Plant Analysis Development) values. Plants harvested at 120 or 180 DAT had a higher content of tanshinone I, tanshinone IIA, cryptotanshinone, and salvianolic acid B compared to those harvested at 60 DAT. This study provides insights for optimizing the time of harvest of danshen to maximize plant growth and bioactive compound production.