Variations in Hormones and Antioxidant Status in Relation to Flowering in Early, Mid, and Late Varieties of Date Palm (Phoenix dactylifera) of United Arab Emirates

The present study was carried out to assess the status of various hormones responsible for the flower induction of Nagal, Lulu, and Khalas date palm varieties in UAE. The nonenzymatic antioxidant compounds and the antioxidant enzymatic activities at preflowering, flowering, and postflowering stages of the date palm varieties were quantified. The ABA and zeatin concentrations were found to be significantly higher during the preflowering stage but gradually decreased during the flowering period and then increased after the flowering stage. Gibberellic acid (GA) concentrations were significantly higher in the early flowering varieties and higher levels of ABA may contribute to the delayed flowering in mid and late varieties. The results on hormone profiling displayed a significant variation between seasons (preflowering, flowering, and postflowering) and also between the three date palms (early, mid, and late flowering varieties). Ascorbic acid (AA) concentration was low at the preflowering stage in the early flowering Nagal (0.694 mg/g dw), which is similar with the late flowering Lulu variety (0.862 mg/g dw). However, Khalas variety showed significantly higher amount of AA content (7.494 mg/g dw) at the preflowering stage when compared to other varieties. In flowering stage, Nagal (0.814 mg/g dw) and Lulu (0.963 mg/g dw) were similar with respect to the production of AA, while the mid flowering variety showed significantly higher amount of AA (9.358 mg/g dw). The Khalas variety produced the highest tocopherol at 4.78 mg/g dw compared to Nagal and Lulu, at 1.997 and 1.908 mg/g dw, respectively, during the preflowering stage. In Nagal variety, the content of reduced glutathione (GSH) at the preflowering stage was 0.507 mg/g dw, which was not significantly different from the flowering and postflowering stages at 0.4 and 0.45 mg/g dw, respectively. The GSH was significantly higher in Khalas compared to Nagal and Lulu varieties, at 1.321 mg/g dw in the preflowering phase followed by 3.347 mg/g dw and 2.349 mg/g dw at the flowering and postflowering phases, respectively. Catalase activity increased with different stages of growth. The lowest catalase activity was observed at the preflowering stage in Khalas (0.116), with similar observations noted during flowering (0.110) and postflowering stage. This study provides an insight into the possible roles of endogenous hormones and antioxidants and in the activities of antioxidant enzymes in the regulation of flower development in date palm varieties

Variations in Hormones and Antioxidant Status in Relation to Flowering in Early, Mid, and Late Varieties of Date Palm (Phoenix dactylifera) of United Arab Emirates

The present study was carried out to assess the status of various hormones responsible for the flower induction of Nagal, Lulu, and Khalas date palm varieties in UAE. The nonenzymatic antioxidant compounds and the antioxidant enzymatic activities at preflowering, flowering, and postflowering stages of the date palm varieties were quantified. The ABA and zeatin concentrations were found to be significantly higher during the preflowering stage but gradually decreased during the flowering period and then increased after the flowering stage. Gibberellic acid (GA) concentrations were significantly higher in the early flowering varieties and higher levels of ABA may contribute to the delayed flowering in mid and late varieties. The results on hormone profiling displayed a significant variation between seasons (preflowering, flowering, and postflowering) and also between the three date palms (early, mid, and late flowering varieties). Ascorbic acid (AA) concentration was low at the preflowering stage in the early flowering Nagal (0.694 mg/g dw), which is similar with the late flowering Lulu variety (0.862 mg/g dw). However, Khalas variety showed significantly higher amount of AA content (7.494 mg/g dw) at the preflowering stage when compared to other varieties. In flowering stage, Nagal (0.814 mg/g dw) and Lulu (0.963 mg/g dw) were similar with respect to the production of AA, while the mid flowering variety showed significantly higher amount of AA (9.358 mg/g dw). The Khalas variety produced the highest tocopherol at 4.78 mg/g dw compared to Nagal and Lulu, at 1.997 and 1.908 mg/g dw, respectively, during the preflowering stage. In Nagal variety, the content of reduced glutathione (GSH) at the preflowering stage was 0.507 mg/g dw, which was not significantly different from the flowering and postflowering stages at 0.4 and 0.45 mg/g dw, respectively. The GSH was significantly higher in Khalas compared to Nagal and Lulu varieties, at 1.321 mg/g dw in the preflowering phase followed by 3.347 mg/g dw and 2.349 mg/g dw at the flowering and postflowering phases, respectively. Catalase activity increased with different stages of growth. The lowest catalase activity was observed at the preflowering stage in Khalas (0.116), with similar observations noted during flowering (0.110) and postflowering stage. This study provides an insight into the possible roles of endogenous hormones and antioxidants and in the activities of antioxidant enzymes in the regulation of flower development in date palm varieties

Traditional uses, pharmacological efficacy, and phytochemistry of Moringa peregrina (Forssk.) Fiori. -A review

Moringa is a sole genus of Moringaceae family with 13 species distributed in the tropical and sub-tropical regions. Among them, Moringa peregrina is one of the species which has wide range of traditional, nutritional, industrial, and medicinal values. The plant parts are used in folk medicine for many human health care purposes including diabetes, wound healing, disinfectant, fever, constipation, muscle pains, slimness, burns, labor pain, hypertension, malaria, stomach disorder, asthma, skin problems, and to expel a retained placenta. In addition to medicinal value, M. peregrina has cultural, spiritual, and religious connections with the native people of Arabian Peninsula. M. peregrina plant parts were tested for many pharmacological activities viz, antioxidant, anti-microbial, anti-diabetic, anti-spasmodic, hypertension, hepatotoxicity, lipid lowering activity, anti-inflammatory, anti-cancer, and memory disorders. Few active molecules belong to the class isothiocyanate, flavonoid, triterpenoid, phytosterol, polyphenol, and glycoside were also isolated, identified and reported for anti-microbial, anti-oxidant, anthelmintic, anti-mutagenic, neuroprotective, anti-cancer, anti-hypertensive, anti-diabetic, anti-infective, anti-allergic, anti-inflammatory, herbicidal, lipid lowering potential, anti-trypanosomal, and cytotoxic activities. So, the aim of the present review is to provide comprehensive information from recognized sources on the traditional uses, pharmacological efficacy and phytochemistry of the desert medicinal plant, M. peregrina. The information provided in this review will be very useful for further studies to develop novel therapeutic drugs

Potassium induced metabolic changes with or without NaCl salinity in maize plants growing in aridlands

This study aimed to determine whether the application of different potassium salts (KCl, K2SO4, KNO3, KH2PO4) can alleviate the NaCl induced salinity in maize plants. NaCl stress decreased maize morphological parameters versus the control. NaCl combined with different type of potassium supplements were not significantly increased the root and stem length versus treatments with NaCl. However, a decrease in chlorophyll 'a', 'b', and total chlorophyll concentrations have been noted in the NaCl stressed plants when compared to control. The chlorophyll content rose with age in the leaves of control and treated plants. When compared to NaCl stressed plants, the chlorophyll content was higher in the NaCl with different types of potassium. Proline content increase in Maize plants under treatment with NaCl when compared to the control. To provide stress protection, several types of potassium are added along with NaCl to further reduce the proline concentration. Compared to the control, the phenol content of Maize plants treated with NaCl marginally increased. The phenol concentration was further raised by the addition of various potassium types along with NaCl, providing additional stress protection. The present study; therefore, suggests that exogenous potassium salts confers tolerance to salt stress to maize plants and have a significant role in partial alleviation of salinity stress especially in arid and semi-arid regions. Keywords: salinity, potassium salt, alleviation, biochemical, pigment

Accumulation of toxic elements in soil and date palm (Phoenix dactylifera L.) through fertilizer application

Dates are the staple food for Arabs as well as the major export crop in the Middle East. In this work, we analyzed the concentration of toxic elements in commonly used fertilizers and evaluated metal accumulation in soil and date palm. Different types of fertilizers randomly selected from fertilizer dealers in the UAE were investigated for their toxic metals. Soil and plant samples collected from continuously fertilized date plantations were analyzed. Sandy loam soil (0–30 cm) samples were collected from date palm plantations continuously fertilized for more than 10 years (11 samples) and unfertilized date palm plantations (11 samples). A significant increase in chromium (Cr) and cadmium (Cd) was observed in the leaves of the fertilized date palms, whereas, in date palm fruits, the concentration of copper (Cu) was higher. A distinct correlation was observed between the total and the available metal concentrations in the soil for Cd and Cu. The average concentrations of toxic metals, however, remained within the limits of those used worldwide. It is important to encourage manufacturers to indicate the concentrations of toxic elements on the fertilizer labels due to environmental and health implications. © 2020 Taylor & Francis Group, LLC.12 month embargo; published online: 05 January 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Potassium induced metabolic changes with or without NaCl salinity in maize plants growing in aridlands

This study aimed to determine whether the application of different potassium salts (KCl, K2SO4, KNO3, KH2PO4) can alleviate the NaCl induced salinity in maize plants. NaCl stress decreased maize morphological parameters versus the control. NaCl combined with different type of potassium supplements were not significantly increased the root and stem length versus treatments with NaCl. However, a decrease in chlorophyll 'a', 'b', and total chlorophyll concentrations have been noted in the NaCl stressed plants when compared to control. The chlorophyll content rose with age in the leaves of control and treated plants. When compared to NaCl stressed plants, the chlorophyll content was higher in the NaCl with different types of potassium. Proline content increase in Maize plants under treatment with NaCl when compared to the control. To provide stress protection, several types of potassium are added along with NaCl to further reduce the proline concentration. Compared to the control, the phenol content of Maize plants treated with NaCl marginally increased. The phenol concentration was further raised by the addition of various potassium types along with NaCl, providing additional stress protection. The present study; therefore, suggests that exogenous potassium salts confers tolerance to salt stress to maize plants and have a significant role in partial alleviation of salinity stress especially in arid and semi-arid regions. Keywords: salinity, potassium salt, alleviation, biochemical, pigment

Effect of abscisic acid on biochemical constituents, enzymatic and non enzymatic antioxidant status of lettuce (Lactuca sativa L.) under varied irrigation regimes

Economically important vegetable crop lettuce (Lactuca sativa L.) of family Asteraceae was selected for the present investigation. It is being cultivated in UAE due to its commercial importance. In lettuce cultivation, the major problem is the requirement of large quantities of irrigation water. The present study was aimed to reduce the water consumption of lettuce cultivation; for that, a varied irrigation regime was used with the application of abscisic acid (ABA). The parameters studied were biochemical constituents, antioxidant potential and antioxidant enzymes’ activities in lettuce plants under drought stress and its response to ABA under stress. Drought stress caused an increase in the biochemical constituents like proline and amino acid contents when compared with control and also increased under individual ABA treatments and treatments under drought stress. The non-enzymatic antioxidant molecules like ascorbate and α-tocopherol showed significant increase under drought condition in lettuce. ABA slightly reduced these contents. The antioxidant enzymes like superoxide dismutase, catalase and peroxidase showed significant increase under drought condition and ABA caused significant enhancement in these antioxidant enzymes under drought stress and also in unstressed conditions, thereby protecting the plants from the deleterious effects of drought stress. From the results of this investigation, it can be concluded that ABA in 10 mg g−1 can be used as a potential tool to minimise the drought stress effects in lettuce cultivation

A Comparative Evaluation of Aquaponic and Soil Systems on Yield and Antioxidant Levels in Basil, an Important Food Plant in Lamiaceae

Greenhouse and aquaponic productions of basil (Ocimum basilicum L.) are well established, but the comparison between these two methods is not studied in detail. A study was conducted to evaluate the performance of basil in both aquaponic and soil systems under greenhouse conditions. The plants were raised in aquaponic beds with ornamental fish and a set of plants was raised in soil pots under a greenhouse setup. The studied parameters were morphological, biochemical and antioxidant levels. In order to analyze the stress effects of an aquaponic system on plant defense mechanism, two different antioxidant enzymes (catalase and peroxidase) were analyzed. Water quality parameters were monitored during the entire study period. Based on the results, there was a significant increase in growth parameters in the aquaponic system when compared to the conventional greenhouse cultivation of basil plants. The photosynthetic parameters showed a decline in the aquaponic system, but the biochemical parameters showed an enhancement in the aquaponic system of growing basil plants. The antioxidants exhibited a significant increase in the aquaponic system, which suggests a water stress effect on the plants induced by the aquaponic growing system. From the results of this study, it can be concluded that the aquaponic system is the best suitable method for basil production in the UAE condition

Biochemical Changes and Antioxidant Variations in Date Palm (<i>Phoenix dactylifera</i> L.) Varieties during Flower Induction and Development

The present investigation was carried out to explore the biochemical changes and antioxidant variations, including non-enzymatic and enzymatic antioxidant variations, in the leaves of different varieties of date palm (Phoenix dactylifera L.) belonging to the early, mid-, and late-flowering categories in the United Arab Emirates. The changes in the protein and phenol concentration; the ascorbic acid, reduced glutathione, and α-tocopherol contents; and the activity of peroxidase and polyphenol oxidase were studied in the leaves during the preflowering, flowering, and postflowering stages of the date palms. Two varieties each from the early (Shaham, Khanezi), mid- (Barhee, Nabthasaif), and late- (Khasab, Fardh) flowering types were used in this study. The protein content in the leaves was higher in the early flowering varieties during the preflowering stage but lower in the other two varieties. The phenol content showed an opposite trend to the protein. There was significant variation in the ascorbic acid content and a reduction in glutathione and α-tocopherol between the leaves of different varieties. Similarly, the activity of the antioxidant enzyme ascorbate peroxidase in the leaves was higher during the preflowering stage in all varieties. The superoxide dismutase (SOD), polyphenol oxidase (PPO), and catalase (CAT) activity was highest in the Bharhee leaves for all the stages. The peroxidase activity (POD) was highest in the Fardh variety of date palm, whereas the Khanezi variety exhibited the lowest activity. This study can be used as a baseline for developing more protocols for understanding the possible roles of biochemicals, antioxidants, antioxidant enzymes, and their interactions in the regulation of flower development in different date palm varieties