Effects of gibberellic acid and chemical and biological (Barvar-2) phosphorus on yield, yield components, and essential oil of Salvia officinalis L.

To investigate the effects of biological and chemical phosphorus fertilizers, and gibberellic acid (GA3) on yield and its components, and essential oil of Salvia officinalis L., a factorial experiment in a randomized complete block design with three replications was conducted in Ghara Chay region, Markazi province, Iran. Experimental treatments included triple super phosphate at three levels (100, 70, and 30 % of the recommended amount), phosphorus bio-fertilizer of Barvar-2 at two levels (application and no application), and GA3 at three levels (0, 100, and 200 ppm). The results showed that Barvar-2, GA3, and triple super phosphate affected yield and its components, and essential oil significantly. The Barvar-2 application increased the yield and essential oil percentage by 7.7 and 18.2% compared to the control, respectively. It also resulted in a slight increase of the major essential oil compounds. Also, the GA3 200 ppm application increased the percentage and essential oil yield by 23.5 and 40.5% compared to the control, respectively. The highest biological yield and essential oil yield were obtained 3751 and 15.52 kg.ha-1, respectivley with the simultaneous application of 100% of the recommended triple super phosphate, Barvar-2, and GA3 200 ppm. The highest α-thujone percentage (27.91%) as the most important essential oil compound was obtained with the simultaneous application of 100% of the recommended triple super phosphate, Barvar-2, and GA3 100 ppm. The combined application of GA3 and Barvar-2 reduced the use of phosphorus chemical fertilizer to achieve better vegetative characteristics, and high yield and essential oil percentage, so that in many traits the simultaneous application of 70% of the recommended triple super phosphate, Barvar-2, and GA3 did not differ significantly from the 100% of the recommended triple super phosphate application. Therefore, with the combined use of GA3 200 ppm and Barvar-2, the amount of phosphorus fertilizer consumption could be reduced by 30% without causing a significant reduction in yield and essential oil of S. officinalis.