Date of Defense
22-6-2026 2:00 PM
Location
F3-032
Document Type
Thesis Defense
Degree Name
Master of Science in Horticulture
College
CVAM
Department
Integrative Agriculture
First Advisor
Prof. Mohammed Alyafei
Keywords
Abiotic stress, Acacia species, Salinity, Drought, Open Top Chamber, Climateresilient landscaping.
Abstract
The presence of abiotic stressors such as salinity, water shortage, hot weather, increase in atmospheric concentration of carbon dioxide and increase in UV-B radiations are major limiting factors to plant growth and survival, especially in desert and semi-desert conditions. These environmental limitations increase the exposure of the United Arab Emirates (UAE) to the lack of freshwater, extensive soil salinization, and rapid effects of climate change. As a result, the discovery of native plant species that can survive under various abiotic stress salinity and drought levels is the key to establishing the sustainable, ecologically adaptive landscaping and the successful ecological rehabilitation options.
This study explored adaptive behaviour of six species of Acacia namely Acacia tortilis, Acacia farnesiana, Acacia nilotica, Acacia seyal, Acacia modesta, and Acacia ehrenbergiana to abiotic stress factors in isolation and in the presence of others. The experimental activity was comprised of two phases. The initial step involved screening of plants to tolerate salinity stress (5,000 ppm and 10,000 ppm NaCl) and droughts. The second phase assessed the responses of plants to co-occurring climate stress processes by an Open Top Chamber (OTC) that had the ability to recreate high temperatures, high CO2 levels, and high UV-B irradiation. Morphological indicators (plant height), physiological (chlorophyll a, chlorophyll b and carotenoid) and biochemical (proline content, total phenolic compounds, and DPPH-based antioxidant activity) indicators were used to assess stress adaptation mechanisms.
The results showed obvious interspecialized difference in the degree of tolerance. The combined stressors had stronger negative effects than single treatments and this was more evident in the more susceptible species. Acacia seyal was the most resilient of all the species under test. It survived with compensatory growth in saline conditions, exhibited partial recovery after exposure to drought, was able to maintain stable levels of photosynthetic pigments, accumulating proline to act as an osmotic regulator and with a high level of antioxidant defence potential. Conversely, the other species were of moderate tolerance to very sensitive especially in cases of long or combined stresses.
Included in
Effect of Abiotic Stress on UAE Native Acacia Plants: Salinity, Drought, UV-B, CO₂, and Temperature under Open Top Chamber (OTC)
F3-032
The presence of abiotic stressors such as salinity, water shortage, hot weather, increase in atmospheric concentration of carbon dioxide and increase in UV-B radiations are major limiting factors to plant growth and survival, especially in desert and semi-desert conditions. These environmental limitations increase the exposure of the United Arab Emirates (UAE) to the lack of freshwater, extensive soil salinization, and rapid effects of climate change. As a result, the discovery of native plant species that can survive under various abiotic stress salinity and drought levels is the key to establishing the sustainable, ecologically adaptive landscaping and the successful ecological rehabilitation options.
This study explored adaptive behaviour of six species of Acacia namely Acacia tortilis, Acacia farnesiana, Acacia nilotica, Acacia seyal, Acacia modesta, and Acacia ehrenbergiana to abiotic stress factors in isolation and in the presence of others. The experimental activity was comprised of two phases. The initial step involved screening of plants to tolerate salinity stress (5,000 ppm and 10,000 ppm NaCl) and droughts. The second phase assessed the responses of plants to co-occurring climate stress processes by an Open Top Chamber (OTC) that had the ability to recreate high temperatures, high CO2 levels, and high UV-B irradiation. Morphological indicators (plant height), physiological (chlorophyll a, chlorophyll b and carotenoid) and biochemical (proline content, total phenolic compounds, and DPPH-based antioxidant activity) indicators were used to assess stress adaptation mechanisms.
The results showed obvious interspecialized difference in the degree of tolerance. The combined stressors had stronger negative effects than single treatments and this was more evident in the more susceptible species. Acacia seyal was the most resilient of all the species under test. It survived with compensatory growth in saline conditions, exhibited partial recovery after exposure to drought, was able to maintain stable levels of photosynthetic pigments, accumulating proline to act as an osmotic regulator and with a high level of antioxidant defence potential. Conversely, the other species were of moderate tolerance to very sensitive especially in cases of long or combined stresses.