Volume 9, Issue 35 (vol. 9, no. 35 2020)                   2020, 9(35): 395-410 | Back to browse issues page

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1- University of Zanjan
2- University of Zanjan , yousefi.alireza@znu.ac.ir
Abstract:   (2127 Views)
Drought stress is one of the imperative limiting factors to plant growth and yield in dry conditions. Abscisic acid (ABA) is one of the most important plant regulators that plays a key role in many physiological and morphological responses under drought conditions. This experiment was carried out to evaluate the interaction between drought stress and ABA on the activity of phenylalanine ammonia- lyase (PAL) and some antioxidant enzymes in dragonhead (Dracocephalum moldavica). This research was conducted as split plot based on complete random block design at research farm of University of Zanjan, during 2016 growth season. Three moisture regimes (well- watered, moderate drought with delay irrigation up to -0.8MPa and severe drought with delay irrigation up to -1.5MPa) were set as main plots and five ABA concentrations (0, 5, 10, 20 and 40 µM) were sets as subplots. The results of this study showed that the effect of watering regimes, ABA and interactions between watering regimes and ABA was significant for PAL, catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) activity, lipid peroxidation, leaf area, total dry weight, plant height and seed yield. Without ABA application, moderate and severe drought stress, increased 15.02 and 30 percent PAL activity, 28.02 and 25.44 percent CAT activity, 48.81 and 35.55 percent APX activity and 77.83 and 88.3 percent POD activity compared to the well- watered condition. Also, exogenous ABA application increased lipid peroxidation and antioxidant enzymes activity compared to control (no ABA application). Without ABA application the moderate and severe drought stress, reduced seed yield by 19.69 and 31.02 percent, respectively, compared to well- watered condition. There was a decreasing trend in seed yield in response to an increase in ABA concentration. The amount of seed yield reduction in plants treated with different concentrations of ABA, 5.18- 14.69 percent under well- watered conditions, 4.22- 20.74 percent under moderate drought conditions and 4.37-33.83 percent under severe drought conditions compared to non- treated plants.
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Type of Study: Research | Subject: Plant Growth Regulators
Received: 2019/02/6 | Accepted: 2019/08/2 | Published: 2020/05/9

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