The biochemical properties of Rosmarinus officinalis L. affected by irrigation water amount and quality.

Water deficiency, especially in the arid and semi-arid areas, necessitates the proper water use and recycling. The objective was to investigate the effects of deficit irrigation as well as treated wastewater on the biochemical properties of Rosmarinus officinalis L., grown in the arid area of Iranshahr, Iran. A split-split plot design on the basis of a complete randomized block design with three replicates was conducted in 2017. Irrigation water treatments of (I1 = 100% of field capacity, FC), 75% of FC (I2), and 50% of FC (I3) as main plots, reduced (S1), and partial irrigation (S2), as sub-plots, and well water (Q1), treated wastewater (Q2), and the combination of Q1 and Q2 (Q3, 50% + 50%), as sub-sub plots, were tested. Plant biochemical properties including proline (Pr), soluble sugars (SS), and essential oil volume (V) and yield (Y) as well as water use efficiency (WUE) were determined. The I2, treatment, compared with I1, increased Pr, SS, V, Y and WUE by 34.4, 31.9, 52.6, 34.3, and 48.1%, respectively. The S2 treatment also increased plant biochemical properties more than 45% related to S1, and Q2 significantly enhanced the measured parameters compared with Q1 and Q3. Treated wastewater improved the essential oil yield of the plant in water deficit conditions. Accordingly, under deficit water conditions, treatment I2S2, and in the case of unfavorable water sources and deficit water conditions, treatment I2Q2 are recommendable to alleviate water stress and improve the biochemical properties of Rosmarinus officinalis L. in the arid areas.