Nada Elloumi

Impact of proline application on cadmium accumulation, mineral nutrition and enzymatic antioxidant defense system of Olea europaea L. cv Chemlali exposed to cadmium stress

Proline plays an important role in plant response to various environmental stresses. However, its involvement in mitigation of heavy metal stress in plants remains elusive. In this study, we examined the effectiveness of exogenous proline (10 and 20 mM) in alleviating cadmium induced inhibitory effects in young olive plants (Olea europaea L. cv. Chemlali) exposed to two Cd levels (10 and 30 mg CdCl2 kg(-1) soil). The Cd treatment induced substantial accumulation of Cd in both root and leaf tissues and a decrease in gas exchange, photosynthetic pigments contents, uptake of essential elements (Ca, Mg and K) and plant biomass. Furthermore, an elevation of antioxidant enzymes activities (superoxide dismutase, catalase, glutathione peroxydase) and proline content in association with relatively high amounts of hydrogen peroxide, thiobarbituric acid reactive substances and electrolyte leakage were observed. Interestingly, the application of exogenous proline alleviated the oxidative damage induced by Cd accumulation. In fact, Cd-stressed olive plants treated with proline showed an increase of antioxidant enzymes activities, photosynthetic activity, nutritional status, plant growth and oil content of olive fruit. Generally, it seems that proline supplementation alleviated the deleterious effects of young olive plants exposed to Cd stress.

Exogenous proline mediates alleviation of cadmium stress by promoting photosynthetic activity, water status and antioxidative enzymes activities of young date palm (Phoenix dactylifera L.)

The ability of exogenous compatible solutes, such as proline, to counteract cadmium (Cd) inhibitory effects in young date palm plants (Phoenix dactylifera L. cv Deglet Nour) was investigated. Two-year-old date palm plants were subjected for five months at different Cd stress levels (0, 10 and 30 mg CdCl2 kg(-1) soil) whether supplied or not with exogenous proline (20mM) added through the irrigation water. Different levels of Cd stress altered plant growth, gas exchanges and chlorophyll content as well as water status, but at different extent among them. In contrast, an increase of antioxidant enzymes activities of Cd-treated plants in association with high amounts of proline content, hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS) and electrolyte leakage (EL) were observed. Interestingly, exogenous proline mitigated the adverse effects of Cd on young date palm. Indeed, it alleviated the oxidative damage induced by Cd accumulation and established better levels of plant growth, water status and photosynthetic activity. Moreover, proline-treated plants showed high antioxidant enzymes activities (superoxide dismutase, catalase and glutathione peroxydase) in roots and leaves as compared to Cd-treated plants.

Ecophysiological responses of almond (Prunus dulcis) seedlings to cadmium stress

Almond (Prunus dulcis L.) seedlings were exposed to 0, 25, 50, 100 and 150 μM of CdCl2 in a solution culture under controlled conditions. The effects of cadmium (Cd) exposure on almond seedlings growth, stomatal architecture, gas exchange and physiological parameters were investigated.Under cadmium stress conditions, significant decrease in fresh and dry weight, length of shoot and chlorophyll content were observed. Stomatal conductance, transpiration and net photosynthetic rates were generally depressed by Cd stress, despite stomatal frequency values and stomatal pore size remained unchanged. Exposure to Cd severely restricted the starch content and increased soluble sugars.

Evolution of several soil properties following amendment with olive mill wastewater

AbstractOlive mill wastewater (OMW) is the main waste product of the olive oil industry and is characterized by high salinity and high organic matter content. Until today, in several olive oil-producing countries, untreated OMW is pumped into agricultural land with potential adverse effects on soil properties. The main objective of this study was to investigate the effects of OMW application on soil physicochemical proprieties. Three OMW levels (50, 100 and 200 m3 ha−1 year−1) were applied over eight successive years. Electrical conductivity, pH, total phosphorus and total nitrogen were studied at different soil depths. Results showed that OMW infiltration caused a modification of soil physicochemical characteristics. The most important effects on soil composition included a significant increase in P and N availability, which enhanced soil fertility in the OMW-treated soil.

Adaptive biochemical and physiological responses of Eriobotrya japonica to fluoride air pollution

The biochemical and physiological effects of fluoride were investigated in loquat trees (Eriobotrya japonica) grown in the vicinity of a phosphate fertilizer plant in Tunisia. Photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were assessed; along with photosynthetic pigments, lipid peroxidation, electrolytic leakage (EL) and total phenolic contents in foliage and roots of trees at different distances from the phosphate fertilizer plant. All assessed parameters showed significant discrepancies in comparison with unpolluted sites. Obtained results showed high oxidative stress indices including H2O2, lipid peroxidation, and EL, SOD, CAT and GPx activities and proline contents in leaves and roots at the polluted sites as compared to control. In contrast, leaf Pn, Gs, E and photosynthetic pigment contents were low as compared to the control. These results indicate that even though antioxidant responses increased near the factory, adverse effects on physiology were pronounced.

Morphological and physiological changes induced in Olea europaea and Prunus dulcis exposed to air fluoride pollution

Air quality biomonitoring using plant leaves has been widely applied to assess the effects of atmospheric pollution. The present study was conducted to investigate the effects of gaseous hydrogen fluoride on the tree leaves of Prunus dulcis and Olea europaea around a phosphate fertilizer-producing factory constituting a major source of pollution. The photosynthesis rate, damaged leaf areas, fluoride accumulation, stomatal architecture and some biochemical responses in the leaves of O. europaea and P. dulcis, were measured. Based on visible injury, gas exchange, stomata responses and certain biochemical parameters, P. dulcis was a sensitive species, and O. europaea was tolerant. Our studies showed that fluoride had a potential effect on stomatal plasticity and confirmed the presence of different control mechanisms for pollution on each leaf surface. It was observed that evergreen tree species highly tolerated fluoride pollutants present in the air, and therefore can be effective in reducing pollutants concentration to a safer level in the environment.

Effect of the phosphogypsum amendment of saline and agricultural soils on growth, productivity and antioxidant enzyme activities of tomato (Solanum lycopersicum L.)

The objective of this study was to investigate the effects of phosphogypsum (PG) amendment on the physiochemical proprieties of saline and agricultural soils along with the growth, productivity and antioxidant enzyme activities of tomato plants (Solanum lycopersicum L.) grown on the amended soils under controlled conditions. Obtained results showed that the amendment of saline soil (H) by PG induced a decrease in pH as well as in electrical conductivity. However, for the non saline soil (MC), there was a decrease in pH associated with an increase in electrical conductivity. For both soils, PG amendment led to an increase in Calcium (Ca) and sodium (Na), and a decrease in potassium (K) in plant tissues. Cadmium (Cd), Zinc (Zn) and Chromium (Cr) contents in different parts of plants increased in proportion with PG concentration in the soils. Apart from Cd, all the analyzed metals in tomato fruit were found to be below the recommended maximum allowable concentration (MAC). Our results showed that PG application, at doses not exceeding 20%, seems to be beneficial for growth, photosynthetic activity and productivity of tomato plants as well as in decreasing salinity of saline soils. In these conditions, the use of PG could be a promising project for the rehabilitation of marginalized and saline ecosystems with either ornamental or non-fruit species. For both soils, a significant accumulation of MDA in shoots was detected, reflecting cell membrane damage especially when the PG amendment reached 20%. Beyond 20 and 40% PG, tomato plants developed an enzymatic antioxidant defense system in response to salinity and heavy metal stress. However, at 80% PG, enzymes activities were significantly inhibited.

Fertilizing Value of Treated Wastewater Under Short Term Irrigation of Olive Tree ( Olea europaea L.)

The reuse of treated wastewater (TWW) for olive irrigation purposes is a potential solution to reduce the fresh water demand and protect the environment. In fact, this effluent is rich in nutrients such as N, P and K, as well as micronutrients, that are considered essentiel for plant growth (Bedbabis et al. in Agric Water Manage, 160:14–21, 2015). Particularly, for plant nursery production, TWW represents an interesting alternative source of irrigation water, which is likely to help face the high water demand.

Magnetic Treatment Effects on Salt Water and Tomato Plants Growth

The magnetic treatment of irrigation water has been developed over the past two decades. It is known as an eco-friendly, non-expansive and easy to use technology.

Treated Olive Mill Wastewater Effects on Soil Properties and Olive Plants

Olive mill wastewater (OMW) production is one of the most serious environmental problems, mainly in countries where olive oil production is an important economic activity. Its contamination potential is related to its high organic load (COD between 40 and 210 g/L) and the significant concentrations of phenolic compounds (between 0.5 and 24 g/L) which are toxic and ecologically noxious.