Effect of irrigation regimes and nitrogen sources on biomass production, water and nitrogen use efficiency and nutrients uptake in coneflower (Echinacea purpurea L.)

Abstract

Water is considered as one of the limited and important resources for agricultural production in arid and semi-arid regions such as Iran. Coneflower has been introduced to Iran in the recent decades. In Iran, coneflower is cultivated in dried and semi-dried regions and used as a medicinal plant in the pharmaceutical industry and as a decorative plant as well. This research was aimed to evaluate the effect of chemical and biological nitrogen on biomass production, water and nitrogen use efficiency and nutrients uptake in coneflower under different irrigation regimes. Field experiment was conducted as split plots in randomized complete blocks with three replications during 2015–2016 in Lordegan, Iran. The experimental treatments included irrigation after 25%, 50% and 75% soil water depletion as the main factor, and non-nitrogen levels (control), nitroxin (contains Azotobacter and Azosperillium bacteria), 40 kg N ha−1 nitrogen, combination of nitroxin and nitrogen and 80 kg N ha−1 were considered as the sub-factor. The use of different levels of nitrogen increased the concentration of nitrogen, phosphorus, nitrate and biological yield in different irrigation levels. The highest nitrogen use efficiency was obtained in the first and second years at irrigation levels following 50% of available water depletion. Moreover, use of 40 kg N ha−1 in the first year and the nitroxin and 40 kg N ha−1 use in the second year resulted in the highest nitrogen use efficiency. The highest water use efficiency in the first year was obtained from irrigation after 25% and 50% of available water depletion and in the second year from irrigation after 50% of soil water depletion. The highest water use efficiency was obtained from use of 80 kg N ha−1 in irrigation after 25% of soil water depletion and use of 80 kg ha−1 N and nitroxin and nitrogen combination in irrigation after 50% of soil water depletion. In general, the results showed that the highest bioyield with less nitrate, higher water and nitrogen use efficiency were obtained using nitrogen and nitroxin combination at irrigation levels after 50% of soil water depletion.