Production protocols for the cultivation of high‐yielding and high‐quality Salvia miltiorrhiza Bunge are needed because of the expanding markets for high‐value Danshen. A 2‐yr pot experiment was conducted to investigate the effect of nitrogen (N) levels and ratios of ammonium nitrogen (NH4+–N) to nitrate nitrogen (NO3−–N) on root development and contents of bioactive components of S. miltiorrhiza Bunge in a soil culture system. The S. miltiorrhiza Bunge seedlings were provided with three N levels (0, 3, and 6 g N plant−1) at the same NH4+:NO3− ratio (0:100) and five NH4+:NO3− ratios (0:100, 25:75, 50:50, 75:25 and 100:0) at the same N level (3 g N plant−1). The plant dry matter (DM), the apparent property of roots, and the contents of cryptotanshinone, tanshinone IIA, total tanshinones, danshensu, and salvianolic B in roots were examined. Plant growth and all the contents of the bioactive components responded negatively to increasing N availability, suggesting that S. miltiorrhiza Bunge is not a nitrophile. The best apparent property of roots and the highest DM were consistently observed when the NH4+:NO3− ratio was 75:25. However, the NH4+:NO3− ratios required for the highest content and yield of bioactive compounds varied among the different compounds. Therefore, in the commercial cultivation of S. miltiorrhiza Bunge, the NH4+:NO3− ratio should be chosen according to the target compound, considering the DM and apparent property of roots and the contents of the desired compounds. Further studies are needed to elucidate the mechanisms in terms of photosynthesis, the activities of key enzymes, and the biosynthetic pathway of the bioactive compounds.

Potassium ions (K+) are important for plant growth and crop yield. However, the effects of K+ deficiency on the biomass of coconut seedlings and the mechanism by which K+ deficiency regulates plant growth remain largely unknown. Therefore, in this study, we compared the physiological, transcriptome, and metabolite profiles of coconut seedling leaves under K+-deficient and K+-sufficient conditions using pot hydroponic experiments, RNA-sequencing, and metabolomics technologies. K+ deficiency stress significantly reduced the plant height, biomass, and soil and plant analyzer development value, as well as K content, soluble protein, crude fat, and soluble sugar contents of coconut seedlings. Under K+ deficiency, the leaf malondialdehyde content of coconut seedlings were significantly increased, whereas the proline (Pro) content was significantly reduced. Superoxide dismutase, peroxidase, and catalase activities were significantly reduced. The contents of endogenous hormones such as auxin, gibberellin, and zeatin were significantly decreased, whereas abscisic acid content was significantly increased. RNA-sequencing revealed that compared to the control, there were 1003 differentially expressed genes (DEGs) in the leaves of coconut seedlings under K+ deficiency. Gene Ontology analysis revealed that these DEGs were mainly related to “integral component of membrane,” “plasma membrane,” “nucleus”, “transcription factor activity,” “sequence-specific DNA binding,” and “protein kinase activity.” Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the DEGs were mainly involved in “MAPK signaling pathway-plant,” “plant hormone signal transduction,” “starch and sucrose metabolism,” “plant-pathogen interaction,” “ABC transporters,” and “glycerophospholipid metabolism.” Metabolomic analysis showed that metabolites related to fatty acids, lipidol, amines, organic acids, amino acids, and flavonoids were generally down-regulated in coconut seedlings under K+ deficiency, whereas metabolites related to phenolic acids, nucleic acids, sugars, and alkaloids were mostly up-regulated. Therefore, coconut seedlings respond to K+ deficiency stress by regulating signal transduction pathways, primary and secondary metabolism, and plant-pathogen interaction. These results confirm the importance of K+ for coconut production, and provide a more in-depth understanding of the response of coconut seedlings to K+ deficiency and a basis for improving K+ utilization efficiency in coconut trees.

To Growth and accumulation of five main bioactive components in the roots of Salvia miltiorrhiza at different growth stages and using different culture systems. We analyzed growth parameters and the accumulation of selected bioactive components in Salvia miltiorrhiza that was grown in quartz sand-pot (hydroponic culture), soil-pot, and field culture systems at 3 growth stages (flower, root swelling, and mature). The highest bioactive compound concentrations (danshensu (DSS), 0.618 mg·g -1 ; salvianolic acid B (SAB), 52.5 mg·g -1 ; cryptotanshinone (CTS), 0.617 mg·g -1 ; tanshinoneⅡA (TSⅡA), 1.11 mg·g -1 ; and total tanshinone (TTS), 2.5 mg·g -1 , at the mature stage) were present in the roots of plants grown in the hydroponic culture system. These concentrations were significantly higher than those of plants grown in the field system. The highest values for root parameters ( longest root length (LRL), 46.72 cm; largest root diameter (LRD), 14.68 mm; and the number of roots per plant (RN), 9.56), plant biomass (shoot dry weight (SDW), 18.9 g·plant -1 ; root dry weight (RDW), 19.6 g·plant -1 , at the mature stage), and yield (DSS, 8.36 mg·plant -1 ; SAB, 657 mg·plant -1 ; CTS, 7.95 mg·plant -1 ; TSⅡA, 15.2 mg·plant -1 ; and TTS, 30.7 mg·plant -1 , at the mature stage) were obtained from plants grown in the field system. Plants grown in the field culture system had significantly greater plant biomass and higher yields of bioactive compounds than plants grown in the quartz sand-pot (hydroponic culture) and soil-pot systems. Greenhouse hydroponic culture provides sufficient bioactive compound accumulation in the roots, but does not stimulate plant growth and root production. Therefore, the field system could greatly improve plant growth and root production in S. miltiorrhiza.

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