Humic acid is natural biological organic, which has a high effect on plant growth and quality. However, the mechanisms of the promoting effect of humic acid on the volatile composition were rarely reported. In this study, the effects of soil application of humic acid on the chemical composition and nutrients uptake of were investigated. Treatments comprised 0, 50, 75 and 100 g m. Essential oil was extracted by hydrodistillation and analyzed using GC-MS and GC-FID. Essential oil content was enhanced by increase of the humic acid level and its content ranged from 0.8% (control) to 2.0% (75 g m). Thirty-two volatile compounds were identified and these compounds were considerably affected by humic acid. The highest percentage of thymol (74.15%), carvacrol (6.20%), -cymene (4.24%), borneol (3.42%),-caryophyllene (1.70%) and -sabinene hydrate (1.35%) as major compounds were observed in under 100 g m humic acid. There was a linear relationship ( = 97%) between humic acid levels and thymol as a major compound. The oils were dominated by oxygenated monoterpenes followed by monoterpene hydrocarbons and sesquiterpene hydrocarbons. Based on the path coefficient analysis, the highest direct effects on essential oil content were observed in monoterpene esters (3.465) and oxygenated sesquiterpenes (3.146). The humic acid application also enhanced the uptake of N, P, K, Mg and Fe in garden thyme. The highest N (2.42%), P (0.75%), K (2.63%), Mg (0.23%) and Fe (1436.58 ppm) were observed in medium supplemented with 100 g m humic acid. In all, the utilization of humic acid could positively change nutrients uptake, essential oil content and its major constituents in .

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Primula heterochroma is indigenous to Caspian coast forests in the north of Iran. Total phenols, total flavnoids, total carotenoids and antioxidant capacity of 50 P. heterochroma accessions were investigated. The highest total phenol (1272.31 mg GA equivalent/100 g fresh weight) and total flavonoids (615 mg catechin/100 g fresh weight) were observed in G5 accession from Saravan. The highest antioxidant activity was observed in G14 accession (73.03 %) from Kacha, followed by G2 accession (69.75 %) and G5 accession (66.84 %) from Saravan. The results of HPLC analysis showed that quercetin-3-glucoside was the major phenolic compound widely found in these accessions followed by chlorogenic acid. There was a linear relationship between the antioxidant capacities and the total phenols and total flavonoid. Inversely, there was no statistically significant correlation between total carotenoid and antioxidant activity. Based on the path coefficient analysis, the maximum direct effect on antioxidant was observed in total phenols (0.908). In addition, the cluster analysis based on Euclidean distance with Unweighted pair-group method using arithmetic average (UPGMA) method separated the accessions into four main groups. Our results supported that Iranian wild primrose accessions possess valuable antioxidant properties for therapeutic and potential medicinal use.

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