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Abstract
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Water deficit stress is one of the most dramatic environmental agents, reduces the growth and efficiency of
cultivated plants. Brassinostroids are ubiquitous steroidal compounds playing vital roles in the processes of
growth and development, pharmaceutically important metabolite production, stress responses and adaptation in
plants. Therefore, in the current study the impact of foliar application of 24-epibresinolide (0, 100 mg L−1)
under different water deficit stress [(100 % field capacity (FC), 60 % FC, and 30 % FC)] was assessed on field
grown sage plants at two different locations of East Azarbaijan (Ahar and Kaleybar) in a factorial experiment
arranged in randomized complete block design (RCBD). The results of combined ANOVA showed that triple
interaction of locations, 24-epibrassinolide treatment and water deficit stress on total dry matter, chlorophyll b
and proline contents were statistically significant. Water deficit had adverse effects on plant height, leaf relative
water content (RWC), dry matter accumulation, and photosynthetic pigments in both cultivated sites, but
spraying with 24-epibrassinolide led to an increase in these traits under water scarcity. The highest H2O2 content
was found in plants subjected to water stress of 30 % FC without 24-epibrassinolide treatment cultivated in Ahar
(a cold semi-arid) region compared to Kaleybar (a cold semi-humid) site. Mean comparison showed that brassinolide
treatment and deficit irrigation of 60 % FC significantly increased (by 33 % and 42.5 %) the essential oil
percentage of plants as compared to the respective control, respectively. Essential oil content was positively
correlated with dry matter accumulation (r0.05 = 0.41) and proline (r0.01 = 0.66) content under the employed
treatments. Based on the GC–MS analysis, about 28 volatile constituents were detected in the essential oil, which
were mainly consisted of α-Terpinolene, α-Thujone, cis-Sabinene hydrate, γ-Terpinene, α-Thujene, Camphor,
and β-Thujone.
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