Effects of organic amendments on nutrient and quality characteristics of Salvia fruticosa Mill at different plant growth stages

Salvia (Salvia fruticosa Mill) is used in traditional medicine and in food and pharmacological industries, and as organically grown plants are preferred it is important to understand how organic soil fertilisation regimes affect the nutritional status and quality of the plant. To address this, an experiment was conducted testing the direct (in the first year) and residual (in the second year) effects of different organic nutrient inputs; control (C: untreated plants), farmyard manure (FYM), chicken manure (CM), vermicompost (VC), and spent mushroom compost (SMC). In the first year, N concentrations in the salvia were increased by 15%-46% and 8%-16%, at beginning of flowering and at full flowering, respectively, indicating a direct effect of the organic amendments. In the second year, the residual effects of the organic amendments increased N concentrations by 8%-37% at beginning of flowering. The organic amendments also affected concentrations of P at full flowering and caused increases of 6%-23% in the first year and by 6%-18% in the second year. Soil organic matter increased by 13%-16% as direct effects of the organic amendments and by 14%-24% as residual effects. Antioxidant activity, total flavonoid and phenolic concentrations of the salvia increased with applications of organic amendments. Total phenolic concentration and antioxidant activity were positively correlated with N, Mn and Mg and negatively correlated with K, Ca and P in the plant leaves. VC and SMC were the most effective amendments for enhancing total flavonoid content, antioxidant activity and plant nutrient concentrations.