1- Tarbiat Modares University
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Extended Abstract
Introduction and Objective: Drought is one of the most important factors affecting plant survival that can have significant effects on their growth, development and productivity, especially in arid and semi-arid regions where climate change has exacerbated this phenomenon. Black hawthorn (Crataegus pentagyana Waldst. & Kit. ex Willd.) is one of the valuable medicinal plants in the forests of northern Iran, which plays an important role in maintaining biodiversity and sustainability of forest ecosystems due to its ability to adapt to different habitats. The aim of this study is to investigate the effect of drought stress on the ecophysiological traits of the leaves of this species in order to find its gas exchange, water relations, and photosynthetic pigments responses under conditions of long-term irrigation interruption and its consequences on seedling health and survival.
Materials and Methods: To conduct this research in a greenhouse experiment at the Faculty of Natural Resources, Tarbiat Modares University, potted seedlings of the medicinal plant Crataegus pentagyana were exposed to withholding watering in 6 treatment levels and with 3 replications in a completely randomized design. Then, on each of the 3rd, 7th, 14th, 21st, 28th and 35th after withholding watering, the photosynthesis rate, transpiration, relative leaf water content, electrolyte leakage and the content of photosynthetic pigments (chlorophyll a, chlorophyll b, chlorophyll a/b ratio, total chlorophyll, carotenoids and total chlorophyll/carotenoid ratio) were measured. Data analysis was performed using one-way ANOVA and Tukey's mean comparison test.
Findings: The results showed that with increasing drought intensity, photosynthesis rate, transpiration and relative leaf water content significantly decreased and electrolyte leakage increased. Also, the content of chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and total chlorophyll/carotenoids decreased under the influence of drought, such that they decreased significantly in severe stresses (days 21, 28, and 35 after withholding watering.
Conclusion: This study revealed that imbalance in the photosynthetic system and disruption in chlorophyll production and synthesis, and in general, significant vulnerability of Crataegus pentagyana seedlings to drought stress, occurs when the seedlings are deprived of water for more than 14 days. This study emphasizes the importance of water resource management in forest nurseries and urban and suburban green spaces, as well as a better understanding of the response of Crataegus pentagyana seedlings to drought stress in order to improve their performance and protect them against climate change.
Introduction and Objective: Drought is one of the most important factors affecting plant survival that can have significant effects on their growth, development and productivity, especially in arid and semi-arid regions where climate change has exacerbated this phenomenon. Black hawthorn (Crataegus pentagyana Waldst. & Kit. ex Willd.) is one of the valuable medicinal plants in the forests of northern Iran, which plays an important role in maintaining biodiversity and sustainability of forest ecosystems due to its ability to adapt to different habitats. The aim of this study is to investigate the effect of drought stress on the ecophysiological traits of the leaves of this species in order to find its gas exchange, water relations, and photosynthetic pigments responses under conditions of long-term irrigation interruption and its consequences on seedling health and survival.
Materials and Methods: To conduct this research in a greenhouse experiment at the Faculty of Natural Resources, Tarbiat Modares University, potted seedlings of the medicinal plant Crataegus pentagyana were exposed to withholding watering in 6 treatment levels and with 3 replications in a completely randomized design. Then, on each of the 3rd, 7th, 14th, 21st, 28th and 35th after withholding watering, the photosynthesis rate, transpiration, relative leaf water content, electrolyte leakage and the content of photosynthetic pigments (chlorophyll a, chlorophyll b, chlorophyll a/b ratio, total chlorophyll, carotenoids and total chlorophyll/carotenoid ratio) were measured. Data analysis was performed using one-way ANOVA and Tukey's mean comparison test.
Findings: The results showed that with increasing drought intensity, photosynthesis rate, transpiration and relative leaf water content significantly decreased and electrolyte leakage increased. Also, the content of chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and total chlorophyll/carotenoids decreased under the influence of drought, such that they decreased significantly in severe stresses (days 21, 28, and 35 after withholding watering.
Conclusion: This study revealed that imbalance in the photosynthetic system and disruption in chlorophyll production and synthesis, and in general, significant vulnerability of Crataegus pentagyana seedlings to drought stress, occurs when the seedlings are deprived of water for more than 14 days. This study emphasizes the importance of water resource management in forest nurseries and urban and suburban green spaces, as well as a better understanding of the response of Crataegus pentagyana seedlings to drought stress in order to improve their performance and protect them against climate change.
Keywords: Black hawthorn, withholding watering, carotenoids, photosynthesis, leaf relative water content, electrolyte leakage
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