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Olive orchards, rainfed managed, are threatened by the current and predicted adverse environmental conditions, which change the yield and quality of olive products, largely known for its benefits to human health. To mitigate these problems, it is highly recommended to perform some adjustments in agronomic practices, such as the use of foliar sprays that cloud help the trees to cope with climate change. During two consecutive years, olive trees were pre-harvest sprayed with kaolin (KL) and salicylic acid (SA) to attenuate the adverse effects of summer stress. Olive yield was increased by 97% and 72% with KL and SA, respectively. Phenolics and antioxidant capacity of both olives and olive oil increased and decreased in the first and second year, respectively, in a closely association with the prevailing climatic conditions. The foliar sprays did not significantly affect the oil quality indices, free acidity, peroxide value and K 232 coefficient and decreased the K 270 coefficient. This study strongly suggests that the applied products might be effective in mitigating the adverse environmental conditions, without substantial changes in fruit and olive oil quality. [ABSTRACT FROM AUTHOR]

Glutathione S -transferases (GST, EC 2.5.1.18) are a group of detoxifying enzymes that catalyze the conjugation of glutathione to certain toxins or xenobiotics. These enzymes are very well characterized in mammals and plants in general but not in the olive tree. In this work the GST specific activity, kinetic behavior, substrate specificity, and protein expression levels have been determined in the leaves, fruits, stems, and roots of olive tree cv. Picual. The results reveal the presence of GST in all the organs, the leaves and roots are containing the highest activity levels. Substrate specificity and molecular mass of subunits differ between organs. The use of the herbicides oxyfluorfen and glyphosate caused barely significant changes in the kinetic behavior and GST protein-expression levels, in general. Only in the stems of the olive tree treated with glyphosate were greater GST specific activity and protein expression detected. As conclusions, GST has been located and characterized in leaves, fruits, stems and roots of olive tree and the action of this enzyme, implied in the detoxification processes in this species, is lightly affected by the soil application of oxyfluorfen and glyphosate. [ABSTRACT FROM AUTHOR]

Highlights: [•] The tillage effect on entomopathogenic fungi (EF) associated to Prays oleae was evaluated. [•] No significant differences were found between the different soil management practices. [•] Seasonal variation on abundance and diversity of EF was detected. [•] Beauveria bassiana was the most abundant entomopathogenic fungi in both soil types. [•] Results provide new insights to the dynamics of EF in the olive grove ecosystem [Copyright &y& Elsevier]

Abstract: Measurements of sap flux were carried out from May 2003 to March 2004 on 6year-old irrigated olive trees of cultivar Chétoui cultivated at 6m×6m spacing in Mornag (36.5°N, 10.2°E), Northern Tunisia. The aim of the research is to evaluate the sap flux technique for its applicability with young olive trees and to estimate their water consumption under field conditions. Three thermal sensors were implanted in the trunk of three olive trees following to North (N), South-East (SE) and South-West (SW) directions. Data were analyzed following to the procedure of that derives from . In this paper, data on probe calibration, wood conductive section estimation and sap flux spatial-variability are presented and discussed. Relationships between sap flux measurements, climate and soil water status have been investigated. Results show that sap flux values vary with sensor position, soil water content and climate demand. Good agreements between sap fluxes and global radiation and reference evapotranspiration measurements were observed. Some variations were recorded under water shortage conditions. Maximum and minimum daily fluxes of 4.5l and 41.0l per tree were found in February 2003 and in August 2003, respectively. Maximum transpiration represented only 53% of the crop evapotranspiration as determined by the F.A.O. method. [Copyright &y& Elsevier]

Abstract: Crop yield forecasting has progressed clearly in the past years, mainly due to the growing demand for modelling. In the present research, considering the Mediterranean vocation for the olive cultivation, olive yield forecasting modelling was analysed, to understand the principal relationships between olive tree production and climate features in a large southern Italy area. The simulation of olive yield has practical application in different price formation activities: in management of cropping systems, formation of stocks, commercialization, making of agricultural policies and zoning. Both meteorological and biological variables were considered, pollen indexes were constructed from daily pollen concentrations evaluated by use of aerobiological methodology. The monitored pollen quantities should be considered as a Proxy variable of the olive orchards located around the volumetric pollen traps, even if the final harvest could be highly dependent on local summer meteorological conditions. The model carried out by use of Panel data analysis has demonstrated a great interpretative capacity, considering contemporary meteorological and biological variables (pollen monitored with volumetric traps). The aggregation of historical data (1999–2008) with cross-section data (10 different pollen monitoring stations) permitted to investigate the variability information related to temporal and geographical dimensions. The entire volume of pollen grains emitted during flowering was redundant to investigate the future fruit formation while the specific and concentrated mass of pollen grains during the days before full flowering was related positively with the final production. The statistical technique utilized permitted to obtain interpretative results common to different geographical areas and not limited by local meteorological conditions. [Copyright &y& Elsevier]

Abstract: The effects of nitrogen deficiency on CO2 assimilation, carbohydrate content and biomass were studied in two olive (Olea europaea L.) cultivars (‘Meski’ and ‘Koroneiki’). One-year-old plants were grown in pots and subjected to four nitrogen levels for 58 days. Nitrogen-deficient plants had significant lower leaf nitrogen and chlorophyll a contents. They also showed a significant reduction in their photosynthetic capacity. A tolerance difference between cultivars was observed: ‘Meski’ proved to be more efficient in maintaining CO2 assimilation rates than ‘Koroneiki’ under nitrogen deficiency, which was reflected by increased photosynthetic nitrogen use efficiency. Accumulation of carbohydrates, especially starch, mannitol, sucrose and glucose, was observed in nitrogen-deficient leaves. This indicates that both the high carbohydrate and the low nitrogen content inhibit photosynthesis in nitrogen-deprived olive plants. Total biomass was strongly reduced (mainly caused by a decrease in leaf dry weight) under nitrogen deficiency for both cultivars, but root:shoot ratio was hardly affected. Elongation of fine roots was enhanced in ‘Koroneiki’ under severe nitrogen-deprivation. [Copyright &y& Elsevier]

The relationships between tree vigour and soil and landscape properties of a rainfed olive orchard located on a marly slope of southern Spain were studied. The different properties and thickness of three soil layers (viz. the secondary carbonate-free layer, the solum, and the layer penetrated by roots), and the properties of the 0–30 cm layer, were used as soil variables. Olive tree vigour and soil properties were found to be strongly correlated. Much of the variability in tree vigour was related to soil morphology. The thickness of the root zone and the average CaCO3 content in the secondary carbonate-free layer and the upper 30 cm of soil accounted for ∼58 and ∼68%, respectively, of the variance in canopy volume. Tree vigour was related to some properties of the root zone, such as clay content and cation exchange capacity, expressed on a surface basis. Topographic properties such as distance to summit, slope gradient and profile curvature were also found to be significantly correlated with tree vigour, but had less influence than intrinsic soil properties. [Copyright &y& Elsevier]

• Mediterranean region is vulnerable to climate change leading to agro-ecosystems degradation. • "Zelmati" olive trees were cultivated in hot desert climate. • Leaf tissues showed an increase of lipid peroxidation, osmoticums and phenolics. • Alteration of olive oil fatty acids proportions. Several studies have highlighted the particular vulnerability of the Mediterranean region regarding climate change. In Tunisia, predictions indicate a temperature increase of 2.7 °C on the horizon of 2050, which may contribute to the degradation of agro-ecosystems and particularly the olive sector. The question that arise: how will the "Zelmati" olive tree behaves in the case of global warming as it is predicted for the south of the country? Therefore, olive trees (Olea europaea L. cv. Zelmati) were cultivated in Kebili-Rjim Maatoug region, which is a desert oasis in southwestern Tunisia characterized by a hot desert climate. The physio-biochemical responses of olive trees as well as olive oil quality characteristics were determined in comparison to those of plants cultivated in the classic region of Sfax-Taoues characterized by an arid climate. Kebili-Rjim Maatoug region exhibited high temperature and insolation, low air humidity and rainfall than Sfax-Taoues region during the different phenological stages of the olive trees. The hot desert climate resulted in a decrease of chlorophyll content, associated with an increase of malondialdehyde, soluble proteins, proline and soluble sugars contents in leaf tissues. Furthermore, polyphenols and carotenoids contents significantly increased (p < 0.05) in olive oil from olive trees grown in Kebili-Rjim Maatoug region. Nevertheless, the oleic acid content decreased below 50%, the palmitic acid exceeded 20% and the linolenic acid exceeded 1%, which was not in accordance with the commercial standards of olive oils. [ABSTRACT FROM AUTHOR]