<p>Water shortage is one of the issues people are facing globally nowadays especial... more <p>Water shortage is one of the issues people are facing globally nowadays especially in arid and semi-arid regions. In these regions the increase in air temperature with slightly changing rates of precipitation cause frequent droughts. This determines the necessity for the usage of irrigation in agriculture that, in turn, makes it the most water consuming sector of economy.</p> <p>The detection of water stress using different approaches is crucial for irrigation scheduling and precise calculation of the volume of water that covers the gap needed for plants’ normal development.</p> <p>It is known that the Photochemical Reflectance Index (PRI) is highly sensitive to the photosynthetic activity of plants. Especially that can be observed for forests and orchards due to the high heterogeneity of canopy structure. In previous studies it was found that PRI can be used as an indicator for monitoring water stress in plants. However, at present, no full answer is given about the limitations of PRI usability and no clear algorithm is formulated for its use in order to detect water stress of plants.</p> <p>In this regard, we concentrate on studying the response of PRI to the water stress of olive trees rain-fed conditions for the case of semi-arid climate (Tunisia). We performed the analysis of data sets for 2021 and 2022, which are, respectively, a dry year and a year of normal water availability. The data sets included meteorological data, PRI measurements made every five minutes, sap flow measurements, soil moisture content values, and dendrometer measurements.</p> <p>On the first stage of our study we processed PRI data sets in order to find an analytic function that best describes daily dynamics of the index. As the result, a new modeling function is constructed to describe an increase in PRI in the middle of the day when minimal PRI values are reached several hours after sunrise and before sunset. Such PRI behavior was mainly observed in sunny days of the dry year.</p> <p>Further, we looked for the correlations of the characteristics of PRI daily dynamics, particularly minimal of PRI, with the values of sap flow that is a main measurable indicator in the class of transpiration and water stress models (see, e.g., https://doi.org/10.1016/j.agwat.2020.106343 ). In this context, the behavior of PRI was different for 2021 and 2022, which, in our opinion, related with weather conditions. For the dry year of 2021 we found a strong correlation between the minimum of PRI and sap flow in morning hours (R<sup>2</sup>= 0,68) during the summer season. For the normal year 2022 the same results are not obvious.</p> <p>In the perspective of our study it is planned to compare the results for the rain-fed site with the measurements obtained under irrigated conditions. The final goal of the research we want to achieve is to propose a reliable approach for separation of physically meaningful part of PRI signal from the noises created by the canopy structure. This will lead us to the reliable algorithm of PRI usage for the detection of plants’ water stress condition.</p>
<p>Water shortage is one of the issues people are facing globally nowadays especial... more <p>Water shortage is one of the issues people are facing globally nowadays especially in arid and semi-arid regions. In these regions the increase in air temperature with slightly changing rates of precipitation cause frequent droughts. This determines the necessity for the usage of irrigation in agriculture that, in turn, makes it the most water consuming sector of economy.</p> <p>The detection of water stress using different approaches is crucial for irrigation scheduling and precise calculation of the volume of water that covers the gap needed for plants’ normal development.</p> <p>It is known that the Photochemical Reflectance Index (PRI) is highly sensitive to the photosynthetic activity of plants. Especially that can be observed for forests and orchards due to the high heterogeneity of canopy structure. In previous studies it was found that PRI can be used as an indicator for monitoring water stress in plants. However, at present, no full answer is given about the limitations of PRI usability and no clear algorithm is formulated for its use in order to detect water stress of plants.</p> <p>In this regard, we concentrate on studying the response of PRI to the water stress of olive trees rain-fed conditions for the case of semi-arid climate (Tunisia). We performed the analysis of data sets for 2021 and 2022, which are, respectively, a dry year and a year of normal water availability. The data sets included meteorological data, PRI measurements made every five minutes, sap flow measurements, soil moisture content values, and dendrometer measurements.</p> <p>On the first stage of our study we processed PRI data sets in order to find an analytic function that best describes daily dynamics of the index. As the result, a new modeling function is constructed to describe an increase in PRI in the middle of the day when minimal PRI values are reached several hours after sunrise and before sunset. Such PRI behavior was mainly observed in sunny days of the dry year.</p> <p>Further, we looked for the correlations of the characteristics of PRI daily dynamics, particularly minimal of PRI, with the values of sap flow that is a main measurable indicator in the class of transpiration and water stress models (see, e.g., https://doi.org/10.1016/j.agwat.2020.106343 ). In this context, the behavior of PRI was different for 2021 and 2022, which, in our opinion, related with weather conditions. For the dry year of 2021 we found a strong correlation between the minimum of PRI and sap flow in morning hours (R<sup>2</sup>= 0,68) during the summer season. For the normal year 2022 the same results are not obvious.</p> <p>In the perspective of our study it is planned to compare the results for the rain-fed site with the measurements obtained under irrigated conditions. The final goal of the research we want to achieve is to propose a reliable approach for separation of physically meaningful part of PRI signal from the noises created by the canopy structure. This will lead us to the reliable algorithm of PRI usage for the detection of plants’ water stress condition.</p>
In the present work, we are assessing the geographical origin and cultivar‐related changes on oli... more In the present work, we are assessing the geographical origin and cultivar‐related changes on olive oil quality and composition in East Algeria. Fruits from the main local olive varieties (Sigoise and Chemlal) were harvested in autumn 2019 growing season from three different geographic areas: semiarid (Setif), arid (Batna), and Saharan (Eloued). Obtained results showed that Chemlal and Sigoise olive oils from Eloued area were the most enriched in tocopherols and phenolic contents, respectively. Sigoise olive oil from Batna area showed the highest values of pigments (carotenoids, chlorophylls). Identified fatty acids using gas chromatography (GC) coupled with mass spectrometry (MS) indicated that Chemlal cultivar olive oil from Batna was the most enriched in saturated fatty acid. However, higher levels of monounsaturated fatty acid were recorded for olive from Eloued and Setif areas. Sigoise cultivar oil displayed higher contents of unsaturated fatty acid in Batna, but higher levels ...
This study aims at characterizing nineteen cultivars of olive trees cultivated in the region of C... more This study aims at characterizing nineteen cultivars of olive trees cultivated in the region of Chott Mariem in the coastal part of Tunisia under rainfed conditions. For that yield and pomological parameters were followed during four years from 2010 to 2013. We noticed a significant (P < 0.05) varietal differences in terms of yield, physical characteristics of the fruit and the oil content. Moreover, there were some fluctuations in the yield between years and a severe alternate bearing was clearly observed. Each cultivar expressed different pomological characters. The largest fruits were given by ‘Tounsi’ and ‘Ascolana’, averaging respectively 7,98 and 6,09 g, whereas ‘Chemlali’ (0,74 g) and ‘Chetoui’ (1,91 g) had the smallest ones. Based on our results, ‘Meski’, ‘Roumi’, ‘Besbessi’, ‘Picholine’ and ‘Lucques’ produced the highest cumulative yield over the four years of study. The highest oil content was observed in ‘Picholine’ (19,62%), ‘Fougi’ (17,42%), ‘Chemlali’ (14,34%) and ‘...
The current study assessed the effect of different soils (clay, EVOOsC, stony, EVOOsS, brown, EVO... more The current study assessed the effect of different soils (clay, EVOOsC, stony, EVOOsS, brown, EVOOsB, limestone and gypsum, EVOOsLG) on the chemico-physical (free acidity, peroxide value, oxidative stability, fatty acids, pigments, colour, viscosity, heat capacity) and thermal (upon DSC) quality of four 'Chemlali' extra virgin olive oils. EVOOsC showed the lowest peroxide value, the highest amount of monounsaturated fatty acids and the narrowest crystallization range. EVOOsLG had the highest content of saturated and polyunsaturated fatty acids as well as the lowest stability to oxidation and melting enthalpy. EVOOsS and EVOOsB revealed the highest viscosity, while the heat capacity measurement didn’t show any difference among the oils. EVOOsB exhibited the highest b* colour parameter in relation to the highest carotenoids content. These preliminary findings have showed that the nature of the soil has an effect on the final quality of EVOO, as also revealed by the PCA analysis.
The present work was aimed at evaluating, under natural situations (field of olive trees, Olea eu... more The present work was aimed at evaluating, under natural situations (field of olive trees, Olea europea cv Chemlali), the effects of one-year agronomic application of an olive mill wastewater (OMW) biologically derived compost. The experimental study was carried in 2014 in an olive orchard situated at Jammel (region of Monastir-Tunisia). An experimental plot (TM, 50 olive trees) was amended on February 2014 (the 'Off year) with 50 m3/ha. The plot TC (50 olive trees) was not amended and served as a control. After one year of OMW application, at harvest, olive fruits were collected and pomological characteristics were determined. Olive oil was extracted and biochemical parameters were studied. Statistical analyses showed that short-term field application of OMW affected negatively carpometric characteristics of olive fruits and oil content. Oil produced from TM had a decreased pigment content and oxidative stability. Moreover, the level of MUFA, particularly oleic acid, as well as ...
&lt;p&gt;Water shortage is one of the issues people are facing globally nowadays especial... more &lt;p&gt;Water shortage is one of the issues people are facing globally nowadays especially in arid and semi-arid regions. In these regions the increase in air temperature with slightly changing rates of precipitation cause frequent droughts. This determines the necessity for the usage of irrigation in agriculture that, in turn, makes it the most water consuming sector of economy.&lt;/p&gt; &lt;p&gt;The detection of water stress using different approaches is crucial for irrigation scheduling and precise calculation of the volume of water that covers the gap needed for plants&amp;#8217; normal development.&lt;/p&gt; &lt;p&gt;It is known that the Photochemical Reflectance Index (PRI) is highly sensitive to the photosynthetic activity of plants. Especially that can be observed for forests and orchards due to the high heterogeneity of canopy structure. In previous studies it was found that PRI can be used as an indicator for monitoring water stress in plants. However, at present, no full answer is given about the limitations of PRI usability and no clear algorithm is formulated for its use in order to detect water stress of plants.&lt;/p&gt; &lt;p&gt;In this regard, we concentrate on studying the response of PRI to the water stress of olive trees rain-fed conditions for the case of semi-arid climate (Tunisia). We performed the analysis of data sets for 2021 and 2022, which are, respectively, a dry year and a year of normal water availability. The data sets included meteorological data, PRI measurements made every five minutes, sap flow measurements, soil moisture content values, and dendrometer measurements.&lt;/p&gt; &lt;p&gt;On the first stage of our study we processed PRI data sets in order to find an analytic function that best describes daily dynamics of the index. As the result, a new modeling function is constructed to describe an increase in PRI in the middle of the day when minimal PRI values are reached several hours after sunrise and before sunset. Such PRI behavior was mainly observed in sunny days of the dry year.&lt;/p&gt; &lt;p&gt;Further, we looked for the correlations of the characteristics of PRI daily dynamics, particularly minimal of PRI, with the values of sap flow that is a main measurable indicator in the class of transpiration and water stress models (see, e.g., https://doi.org/10.1016/j.agwat.2020.106343 ). In this context, the behavior of PRI was different for 2021 and 2022, which, in our opinion, related with weather conditions. For the dry year of 2021 we found a strong correlation between the minimum of PRI and sap flow in morning hours (R&lt;sup&gt;2&lt;/sup&gt;= 0,68) during the summer season. For the normal year 2022 the same results are not obvious.&lt;/p&gt; &lt;p&gt;In the perspective of our study it is planned to compare the results for the rain-fed site with the measurements obtained under irrigated conditions. The final goal of the research we want to achieve is to propose a reliable approach for separation of physically meaningful part of PRI signal from the noises created by the canopy structure. This will lead us to the reliable algorithm of PRI usage for the detection of plants&amp;#8217; water stress condition.&lt;/p&gt;
&lt;p&gt;Water shortage is one of the issues people are facing globally nowadays especial... more &lt;p&gt;Water shortage is one of the issues people are facing globally nowadays especially in arid and semi-arid regions. In these regions the increase in air temperature with slightly changing rates of precipitation cause frequent droughts. This determines the necessity for the usage of irrigation in agriculture that, in turn, makes it the most water consuming sector of economy.&lt;/p&gt; &lt;p&gt;The detection of water stress using different approaches is crucial for irrigation scheduling and precise calculation of the volume of water that covers the gap needed for plants&amp;#8217; normal development.&lt;/p&gt; &lt;p&gt;It is known that the Photochemical Reflectance Index (PRI) is highly sensitive to the photosynthetic activity of plants. Especially that can be observed for forests and orchards due to the high heterogeneity of canopy structure. In previous studies it was found that PRI can be used as an indicator for monitoring water stress in plants. However, at present, no full answer is given about the limitations of PRI usability and no clear algorithm is formulated for its use in order to detect water stress of plants.&lt;/p&gt; &lt;p&gt;In this regard, we concentrate on studying the response of PRI to the water stress of olive trees rain-fed conditions for the case of semi-arid climate (Tunisia). We performed the analysis of data sets for 2021 and 2022, which are, respectively, a dry year and a year of normal water availability. The data sets included meteorological data, PRI measurements made every five minutes, sap flow measurements, soil moisture content values, and dendrometer measurements.&lt;/p&gt; &lt;p&gt;On the first stage of our study we processed PRI data sets in order to find an analytic function that best describes daily dynamics of the index. As the result, a new modeling function is constructed to describe an increase in PRI in the middle of the day when minimal PRI values are reached several hours after sunrise and before sunset. Such PRI behavior was mainly observed in sunny days of the dry year.&lt;/p&gt; &lt;p&gt;Further, we looked for the correlations of the characteristics of PRI daily dynamics, particularly minimal of PRI, with the values of sap flow that is a main measurable indicator in the class of transpiration and water stress models (see, e.g., https://doi.org/10.1016/j.agwat.2020.106343 ). In this context, the behavior of PRI was different for 2021 and 2022, which, in our opinion, related with weather conditions. For the dry year of 2021 we found a strong correlation between the minimum of PRI and sap flow in morning hours (R&lt;sup&gt;2&lt;/sup&gt;= 0,68) during the summer season. For the normal year 2022 the same results are not obvious.&lt;/p&gt; &lt;p&gt;In the perspective of our study it is planned to compare the results for the rain-fed site with the measurements obtained under irrigated conditions. The final goal of the research we want to achieve is to propose a reliable approach for separation of physically meaningful part of PRI signal from the noises created by the canopy structure. This will lead us to the reliable algorithm of PRI usage for the detection of plants&amp;#8217; water stress condition.&lt;/p&gt;
In the present work, we are assessing the geographical origin and cultivar‐related changes on oli... more In the present work, we are assessing the geographical origin and cultivar‐related changes on olive oil quality and composition in East Algeria. Fruits from the main local olive varieties (Sigoise and Chemlal) were harvested in autumn 2019 growing season from three different geographic areas: semiarid (Setif), arid (Batna), and Saharan (Eloued). Obtained results showed that Chemlal and Sigoise olive oils from Eloued area were the most enriched in tocopherols and phenolic contents, respectively. Sigoise olive oil from Batna area showed the highest values of pigments (carotenoids, chlorophylls). Identified fatty acids using gas chromatography (GC) coupled with mass spectrometry (MS) indicated that Chemlal cultivar olive oil from Batna was the most enriched in saturated fatty acid. However, higher levels of monounsaturated fatty acid were recorded for olive from Eloued and Setif areas. Sigoise cultivar oil displayed higher contents of unsaturated fatty acid in Batna, but higher levels ...
This study aims at characterizing nineteen cultivars of olive trees cultivated in the region of C... more This study aims at characterizing nineteen cultivars of olive trees cultivated in the region of Chott Mariem in the coastal part of Tunisia under rainfed conditions. For that yield and pomological parameters were followed during four years from 2010 to 2013. We noticed a significant (P < 0.05) varietal differences in terms of yield, physical characteristics of the fruit and the oil content. Moreover, there were some fluctuations in the yield between years and a severe alternate bearing was clearly observed. Each cultivar expressed different pomological characters. The largest fruits were given by ‘Tounsi’ and ‘Ascolana’, averaging respectively 7,98 and 6,09 g, whereas ‘Chemlali’ (0,74 g) and ‘Chetoui’ (1,91 g) had the smallest ones. Based on our results, ‘Meski’, ‘Roumi’, ‘Besbessi’, ‘Picholine’ and ‘Lucques’ produced the highest cumulative yield over the four years of study. The highest oil content was observed in ‘Picholine’ (19,62%), ‘Fougi’ (17,42%), ‘Chemlali’ (14,34%) and ‘...
The current study assessed the effect of different soils (clay, EVOOsC, stony, EVOOsS, brown, EVO... more The current study assessed the effect of different soils (clay, EVOOsC, stony, EVOOsS, brown, EVOOsB, limestone and gypsum, EVOOsLG) on the chemico-physical (free acidity, peroxide value, oxidative stability, fatty acids, pigments, colour, viscosity, heat capacity) and thermal (upon DSC) quality of four 'Chemlali' extra virgin olive oils. EVOOsC showed the lowest peroxide value, the highest amount of monounsaturated fatty acids and the narrowest crystallization range. EVOOsLG had the highest content of saturated and polyunsaturated fatty acids as well as the lowest stability to oxidation and melting enthalpy. EVOOsS and EVOOsB revealed the highest viscosity, while the heat capacity measurement didn’t show any difference among the oils. EVOOsB exhibited the highest b* colour parameter in relation to the highest carotenoids content. These preliminary findings have showed that the nature of the soil has an effect on the final quality of EVOO, as also revealed by the PCA analysis.
The present work was aimed at evaluating, under natural situations (field of olive trees, Olea eu... more The present work was aimed at evaluating, under natural situations (field of olive trees, Olea europea cv Chemlali), the effects of one-year agronomic application of an olive mill wastewater (OMW) biologically derived compost. The experimental study was carried in 2014 in an olive orchard situated at Jammel (region of Monastir-Tunisia). An experimental plot (TM, 50 olive trees) was amended on February 2014 (the 'Off year) with 50 m3/ha. The plot TC (50 olive trees) was not amended and served as a control. After one year of OMW application, at harvest, olive fruits were collected and pomological characteristics were determined. Olive oil was extracted and biochemical parameters were studied. Statistical analyses showed that short-term field application of OMW affected negatively carpometric characteristics of olive fruits and oil content. Oil produced from TM had a decreased pigment content and oxidative stability. Moreover, the level of MUFA, particularly oleic acid, as well as ...
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