Effect of growth regulators and microfertilizers on yield of Echinacea purpurea L. depending on weather conditions

In the Western Ciscaucasia, frequent droughts lead to a decrease in the yield of Echinacea purpurea L., which is a base for immunostimulating preparations. It is possible to mitigate the effect of sharp fluctuations in weather conditions by using growth regulators and microfertilizers, the exogenous application of which allows mobilizing the potential capabilities of the plant organism aimed at increasing its bioproductivity. The purpose of the research was to study the effect of foliar application the growth regulator Zircon and silicon-containing microfertilizer Siliplant on the yield of Echinacea biomass depending on the weather conditions. The weather conditions during the research years differed. Thus, in 2011- 2014, the average daily air temperatures and the amount of precipitation from May to July were almost at the level of the average annual values. And starting from 2015 there has been a significant increase in temperatures and a decrease in moisture availability. Foliar treatment of Echinacea purpurea with Zircon and Siliplant under drought ensured an increase in the biomass yield by 15-20% compared to the control, under stable weather conditions - by 11-18%. Their combined application increased the yield of the green weight by 24-31%, under stable weather conditions -by 18-24%. The high efficiency of the preparations was manifested in the growth of the root system under drought conditions, where the increase in yield was 40-43% at their combined application. The content of hydroxycinnamic acids in the raw material increased by 4-6% regardless of weather conditions and by 910% in the variant Siliplant + Zircon application. Losses of biomass yield under hydrothermal stress amounted to 1-10%, of roots - 4-5%, while in the control the values were 15-25 and 18%, respectively. The biggest preservation of the yield was noted in the Siliplant + Zircon variant, where there was even a small increase in biomass yield - by 4-9%, in roots -by 4%.