| Abstrakt: |
Plant growth regulators are an appealing and fast-track method for overcoming the drastic effects of drought. Paclobutrazol (PBZ), a member of the triazole family, is a versatile chemical compound that acts as a growth regulator and retardant. This study assessed the effect of two concentrations of PBZ (30 and 60 mg L–1) on strawberry plants under two drought stress levels [40% and 80% field capacity (FC)] and 100% FC set as the control. The findings revealed that drought significantly affected strawberry plants, elevating the levels of reactive oxygen species (ROS) like hydrogen peroxide (H2O2), hydroxide ion (OH–), and superoxide ion (O2–), and reactive carbonyl species (RCS) like malondialdehyde (MDA), methylglyoxal (MG), 4-hydroxy-(E)-2-hexenal (HEE), acetone, propionaldehyde (PD), acetaldehyde (ACD), and formaldehyde (FMD), due to decreased antioxidant activities. The study also found that glutathione (GSH) is crucial in ROS and RCS scavenging. In addition, the presence of thiol groups (–SH compounds) in strawberry plants under moderate and severe drought stress was a noteworthy finding. Due to excess thiol production, drought stress significantly decreased MDA, MG, HEE, PD, ACD, FMD, and acetone levels. However, PBZ application decreased the total thiol content in strawberry leaves. Furthermore, PBZ improved plant growth and development by modulating the production of endogenous growth hormones such as abscisic acid, indole-3-acetic acid, ethylene, gibberellic acid, strigolactones, and brassinosteroids, while increasing cytokinin levels. These changes led to enhanced enzymatic and non-enzymatic antioxidant activities, reduced stomatal conductance, increased relative water content in leaves, improved chlorophyll content, elevated photosynthetic rate, and ultimately enhanced increased fruit yield. Moreover, drought stress enhanced metabolic activity (α-tocopherol, β-carotene, total phenolic content, anthocyanin, and proline) in strawberry plants, indicating that metabolites also function as stress scavengers/protectors. This study shed light on crucial physiological mechanisms underlying ROS- and RCS-induced oxidative stresses and their management in strawberry plants. [ABSTRACT FROM AUTHOR] |
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