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Papers by Pasquale Giorio

Plant Biosystems, 2011

Canopy light interception (CPFDInt), spectral irradiance, leaf water potential, gas- exchange and... more Canopy light interception (CPFDInt), spectral irradiance, leaf water potential, gas- exchange and optical properties were measured in an irrigated vineyard (Vitis vinifera L. cv Montepulciano) trained to the so-called tendone system in which leaf area index (LAI) was varied by means of 50% (T50) or 75% (T75) cluster removal. The 20.5 t ha−1 yield in the unthinned treatment (UT) decreased by only 36% in T50 and by 52% in T75. LAI and CPFDInt similarly increased until summer pruning when LAI was 1.75 m2 m−2 in UT, and 25.6% or 62.2% higher in T50 and T75, respectively. The two thinned treatments had only 12.4% higher CPFDInt than in UT (1167.1 μmol m−2 s−1) due to the increased leaf self-shading. The red-to-far red ratio (R: FR) was as low as 0.10 below the canopy. Light-saturated CO2 assimilation (A max) in June averaged 14.4 μmol m−2 s−1 in sun-exposed leaves, and 7.6 μmol m−2 s−1 in shade leaves. By contrast, the apparent quantum yield of CO2 assimilation (e) was not significantly affected by leaf position, averaging 0.029 and 0.070 mol mol−1 in June and October, respectively. Middle and low canopy leaves had only 27 or 6%, respectively, of the top canopy leaves actual CO2 assimilation rate.

Environmental science & …, 2006

Gas exchanges of whole canopy can be studied by covering entire plants with a chamber and using p... more Gas exchanges of whole canopy can be studied by covering entire plants with a chamber and using portable infrared gas analyzers (IRGAs) to measure CO 2 and H 2 O exchanged with the air blown through the chamber enclosure. The control of temperature rise inside the chamber, which should be kept low, and the accurate measurement of the air flow are two crucial aspects for realistic and precise estimation of photosynthesis and transpiration. An automated open-system plant chamber (clear flexible balloon enclosure) for small plants was developed to ameliorate such a technique. The temperature rise is here predicted by heat balance analysis inside the chamber. The analysis shows that when as much as 500 W m 2 of solar radiation is converted to sensible heat, a flow rate of 0.98 mol s -1 (≈20 L s -1 ) of air blown into a cylindershaped enclosure (0.8 m high, 0.5 m wide) is adequate to limit temperature increase to 2 K. An improved calibration for the measurement of the chamber airflow was obtained by combining the use of a Pitot tube anemometer with the classical CO 2 injection approach. The concentration increase due to the injection of CO 2 at a known rate into the chamber was predicted by the air flow calculated from the "Pitot" air velocity. The turbulent regime of air assured that a single-point Pitot measurement was enough for a good estimation (slope ) 0.99; R 2 ) 0.999) of the actual air flow. The open-system chamber was tested on potted sunflower (Helianthus annuus, L.) and maize (Zea mays, L.) plants under variable solar radiation, temperature, and air humidity during the daytime. As expected, similar rates of maximal leaf-area based photosynthesis (about 40 µmol m -2 s -1 ) were observed in the two species confirming the reliability of our system. The consistency of data also resulted from the typical relationships observed between photosynthetic rate and light.

Environmental and Experimental Botany, 2000

Sunflower (Helianthus annuus) was grown in both open-field and outdoor potted conditions in South... more Sunflower (Helianthus annuus) was grown in both open-field and outdoor potted conditions in Southern Italy, and irrigated with water having electrical conductivity ranging between 0.9 and 15.6 dS m−1 obtained by different NaCl concentrations. The aim of the work was to study the leaf area and photosynthetic responses of sunflower to mild salt stress. The response curve (A/ci) of assimilation (A) to leaf internal CO2 concentration (ci) was used to determine leaf gas-exchange parameters, in order to evaluate stomatal and non-stomatal limitations to photosynthesis in relation to salt stress. In the field, a reduction of 19% in leaf area expansion occurred, while no correlation was observed between Ψl and stomatal conductance to water vapour (gsw) ranging between 0.76 and 1.35 mol m−2 s−1. This result was also evident at a higher salinity level reached in the pot experiment where leaf osmotic potential (ψs) varied from −1.35 to −2.67 MPa as compared with the field experiment, where ψs ranged from −1.15 to −1.42 MPa. Considering the two experiments as a unique data set, the assimilation rate, the stomatal conductance to CO2 (gsc) and the sensitivity of A to ci variation (g*) were not significantly influenced by salinity in the whole range of ψs. As a consequence, the stomatal and non-stomatal limitations to photosynthesis were not affected by salt treatment, averaging around 20 and 80%, respectively. The variation in A (from 44 to 29 μmol m−2 s−1) was paralleled by the variation in gsc (from 0.47 to 0.84 mol m−2 s−1), with a remarkable constancy of both ci (200±12.5 μmol mol−1) and normalized water-use efficiency (5±0.7 μmol mmol−1 kPa), showing the optimal behaviour of the plant processes. These findings indicate that, under mild salt stress, the same as observed under water deficit, sunflower controls assimilation mainly by modulating leaf area rather than by stomatal closure, and that non-stomatal limitation of photosynthesis was not affected at all by the level of salinity reached in this study.

Environmental and Experimental Botany, 2003

The use of the compensation heat-pulse velocity (CHPV) technique to estimate sap flow in olive tr... more The use of the compensation heat-pulse velocity (CHPV) technique to estimate sap flow in olive trees as a means of irrigation scheduling can be a difficult task because of the naturally heterogeneity of hydraulic functioning of sapwood area in this species. As a result, the monitoring of an unreasonably large number of both trees and CHPV gauges per tree is needed for accurate estimation of orchard transpiration. The approach used in this paper restricts the monitoring of a large number of both trees and gauges to a very short time (a day) and allows the long term estimation of transpiration of several olive trees by the continuous monitoring of a sole CHPV gauge installed in a single tree. In an experimental olive orchard in southern Italy, we monitored six CHPV gauges in three well irrigated trees (treatment T100) and six CHPV gauges in three rain-fed trees (treatment T0) at half hour intervals for 60 days during summer 1999. For each i th gauge at each day, we linearly regressed the sap flow (Q i , l h (1 ) against the mean sap flow of the all other n(/1 gauges of the same treatment (Qm i ). The regression parameters were used to obtain an estimation of Qm i (EQm i ) throughout the trial using the data of any single i th gauge. In order to test the prediction power of the model of i th gauge, the estimated mean sap flow (EQm i ) values were regressed day by day against the actually measured Qm i . The same procedure was also applied at the time scale of a day, that is to the daily cumulative value of Q i and Qm i . In all cases, we obtained high statistical significance of the models applied to data as confirmed by the high adjusted R 2 estimates. Our analyses show the feasibility of estimating the transpiration rate of many trees by monitoring sap flow in a single tree by the use of a sole CHPV gauge. The results of this work indicate that CHPV can be a useful and powerful method for irrigation scheduling for olive and other tree species. #

Environmental and Experimental Botany, 1999

Stomatal behaviour, leaf water status and photosynthetic response in relation to long-term water ... more Stomatal behaviour, leaf water status and photosynthetic response in relation to long-term water deficit were investigated in southern Italy on young trees of Olive (Olea europaea) to clarify mechanisms of stomatal control. Trees were subjected to three irrigation treatments, T0, T33 and T66 that received 0, 33 and 66%, respectively, of crop evapotranspiration by a drip irrigation system. The prolonged drought during the summer significantly affected soil and leaf water status and gas exchange. In the unirrigated treatment, the drought decreased volumetric soil water content from 30 to 21%, midday leaf water potential from −1.5 to −3.4 MPa, relative water content from 84 to 74% and stomatal conductance to water vapour from 0.190 to 0.023 mol m−2 s−1. Similar responses to milder water deficit were observed for the irrigated treatments. Good positive relationships were found between stomatal conductance and both leaf water potential and soil moisture. This indicates that both hydraulic feedback and feed-forward mechanisms could be invoked in the response of stomata to soil drying. In late summer, a significant re-increase in both leaf water potential and relative water content was observed in the absence of significant rainfall. Conversely, stomatal conductance remained at quite a low value as did soil moisture. The disruption of the positive relationship between stomatal conductance and leaf water potential at constant soil moisture clearly indicates that soil or root water status directly affected stomatal conductance, minimising the possibility of a feedback mechanism through leaf water status. Photosynthetic CO2 assimilation in T0 decreased during the season from 14 to 3.3 μmol m−2 s−1, the minimum value that was found in correspondence with minimum leaf water potential and soil moisture. The response curve of assimilation to intercellular CO2 partial pressure showed that photosynthetic metabolism was greatly depressed by long-term water deficit, with a reduction of 48% for the slope at low CO2 and of 67% for photosynthetic assimilation at high CO2, and that it played a greater role than stomata in limiting photosynthesis.

Plant Biosystems, 2011

Canopy light interception (CPFDInt), spectral irradiance, leaf water potential, gas- exchange and... more Canopy light interception (CPFDInt), spectral irradiance, leaf water potential, gas- exchange and optical properties were measured in an irrigated vineyard (Vitis vinifera L. cv Montepulciano) trained to the so-called tendone system in which leaf area index (LAI) was varied by means of 50% (T50) or 75% (T75) cluster removal. The 20.5 t ha−1 yield in the unthinned treatment (UT) decreased by only 36% in T50 and by 52% in T75. LAI and CPFDInt similarly increased until summer pruning when LAI was 1.75 m2 m−2 in UT, and 25.6% or 62.2% higher in T50 and T75, respectively. The two thinned treatments had only 12.4% higher CPFDInt than in UT (1167.1 μmol m−2 s−1) due to the increased leaf self-shading. The red-to-far red ratio (R: FR) was as low as 0.10 below the canopy. Light-saturated CO2 assimilation (A max) in June averaged 14.4 μmol m−2 s−1 in sun-exposed leaves, and 7.6 μmol m−2 s−1 in shade leaves. By contrast, the apparent quantum yield of CO2 assimilation (e) was not significantly affected by leaf position, averaging 0.029 and 0.070 mol mol−1 in June and October, respectively. Middle and low canopy leaves had only 27 or 6%, respectively, of the top canopy leaves actual CO2 assimilation rate.

Environmental science & …, 2006

Gas exchanges of whole canopy can be studied by covering entire plants with a chamber and using p... more Gas exchanges of whole canopy can be studied by covering entire plants with a chamber and using portable infrared gas analyzers (IRGAs) to measure CO 2 and H 2 O exchanged with the air blown through the chamber enclosure. The control of temperature rise inside the chamber, which should be kept low, and the accurate measurement of the air flow are two crucial aspects for realistic and precise estimation of photosynthesis and transpiration. An automated open-system plant chamber (clear flexible balloon enclosure) for small plants was developed to ameliorate such a technique. The temperature rise is here predicted by heat balance analysis inside the chamber. The analysis shows that when as much as 500 W m 2 of solar radiation is converted to sensible heat, a flow rate of 0.98 mol s -1 (≈20 L s -1 ) of air blown into a cylindershaped enclosure (0.8 m high, 0.5 m wide) is adequate to limit temperature increase to 2 K. An improved calibration for the measurement of the chamber airflow was obtained by combining the use of a Pitot tube anemometer with the classical CO 2 injection approach. The concentration increase due to the injection of CO 2 at a known rate into the chamber was predicted by the air flow calculated from the "Pitot" air velocity. The turbulent regime of air assured that a single-point Pitot measurement was enough for a good estimation (slope ) 0.99; R 2 ) 0.999) of the actual air flow. The open-system chamber was tested on potted sunflower (Helianthus annuus, L.) and maize (Zea mays, L.) plants under variable solar radiation, temperature, and air humidity during the daytime. As expected, similar rates of maximal leaf-area based photosynthesis (about 40 µmol m -2 s -1 ) were observed in the two species confirming the reliability of our system. The consistency of data also resulted from the typical relationships observed between photosynthetic rate and light.

Environmental and Experimental Botany, 2000

Sunflower (Helianthus annuus) was grown in both open-field and outdoor potted conditions in South... more Sunflower (Helianthus annuus) was grown in both open-field and outdoor potted conditions in Southern Italy, and irrigated with water having electrical conductivity ranging between 0.9 and 15.6 dS m−1 obtained by different NaCl concentrations. The aim of the work was to study the leaf area and photosynthetic responses of sunflower to mild salt stress. The response curve (A/ci) of assimilation (A) to leaf internal CO2 concentration (ci) was used to determine leaf gas-exchange parameters, in order to evaluate stomatal and non-stomatal limitations to photosynthesis in relation to salt stress. In the field, a reduction of 19% in leaf area expansion occurred, while no correlation was observed between Ψl and stomatal conductance to water vapour (gsw) ranging between 0.76 and 1.35 mol m−2 s−1. This result was also evident at a higher salinity level reached in the pot experiment where leaf osmotic potential (ψs) varied from −1.35 to −2.67 MPa as compared with the field experiment, where ψs ranged from −1.15 to −1.42 MPa. Considering the two experiments as a unique data set, the assimilation rate, the stomatal conductance to CO2 (gsc) and the sensitivity of A to ci variation (g*) were not significantly influenced by salinity in the whole range of ψs. As a consequence, the stomatal and non-stomatal limitations to photosynthesis were not affected by salt treatment, averaging around 20 and 80%, respectively. The variation in A (from 44 to 29 μmol m−2 s−1) was paralleled by the variation in gsc (from 0.47 to 0.84 mol m−2 s−1), with a remarkable constancy of both ci (200±12.5 μmol mol−1) and normalized water-use efficiency (5±0.7 μmol mmol−1 kPa), showing the optimal behaviour of the plant processes. These findings indicate that, under mild salt stress, the same as observed under water deficit, sunflower controls assimilation mainly by modulating leaf area rather than by stomatal closure, and that non-stomatal limitation of photosynthesis was not affected at all by the level of salinity reached in this study.

Environmental and Experimental Botany, 2003

The use of the compensation heat-pulse velocity (CHPV) technique to estimate sap flow in olive tr... more The use of the compensation heat-pulse velocity (CHPV) technique to estimate sap flow in olive trees as a means of irrigation scheduling can be a difficult task because of the naturally heterogeneity of hydraulic functioning of sapwood area in this species. As a result, the monitoring of an unreasonably large number of both trees and CHPV gauges per tree is needed for accurate estimation of orchard transpiration. The approach used in this paper restricts the monitoring of a large number of both trees and gauges to a very short time (a day) and allows the long term estimation of transpiration of several olive trees by the continuous monitoring of a sole CHPV gauge installed in a single tree. In an experimental olive orchard in southern Italy, we monitored six CHPV gauges in three well irrigated trees (treatment T100) and six CHPV gauges in three rain-fed trees (treatment T0) at half hour intervals for 60 days during summer 1999. For each i th gauge at each day, we linearly regressed the sap flow (Q i , l h (1 ) against the mean sap flow of the all other n(/1 gauges of the same treatment (Qm i ). The regression parameters were used to obtain an estimation of Qm i (EQm i ) throughout the trial using the data of any single i th gauge. In order to test the prediction power of the model of i th gauge, the estimated mean sap flow (EQm i ) values were regressed day by day against the actually measured Qm i . The same procedure was also applied at the time scale of a day, that is to the daily cumulative value of Q i and Qm i . In all cases, we obtained high statistical significance of the models applied to data as confirmed by the high adjusted R 2 estimates. Our analyses show the feasibility of estimating the transpiration rate of many trees by monitoring sap flow in a single tree by the use of a sole CHPV gauge. The results of this work indicate that CHPV can be a useful and powerful method for irrigation scheduling for olive and other tree species. #

Environmental and Experimental Botany, 1999

Stomatal behaviour, leaf water status and photosynthetic response in relation to long-term water ... more Stomatal behaviour, leaf water status and photosynthetic response in relation to long-term water deficit were investigated in southern Italy on young trees of Olive (Olea europaea) to clarify mechanisms of stomatal control. Trees were subjected to three irrigation treatments, T0, T33 and T66 that received 0, 33 and 66%, respectively, of crop evapotranspiration by a drip irrigation system. The prolonged drought during the summer significantly affected soil and leaf water status and gas exchange. In the unirrigated treatment, the drought decreased volumetric soil water content from 30 to 21%, midday leaf water potential from −1.5 to −3.4 MPa, relative water content from 84 to 74% and stomatal conductance to water vapour from 0.190 to 0.023 mol m−2 s−1. Similar responses to milder water deficit were observed for the irrigated treatments. Good positive relationships were found between stomatal conductance and both leaf water potential and soil moisture. This indicates that both hydraulic feedback and feed-forward mechanisms could be invoked in the response of stomata to soil drying. In late summer, a significant re-increase in both leaf water potential and relative water content was observed in the absence of significant rainfall. Conversely, stomatal conductance remained at quite a low value as did soil moisture. The disruption of the positive relationship between stomatal conductance and leaf water potential at constant soil moisture clearly indicates that soil or root water status directly affected stomatal conductance, minimising the possibility of a feedback mechanism through leaf water status. Photosynthetic CO2 assimilation in T0 decreased during the season from 14 to 3.3 μmol m−2 s−1, the minimum value that was found in correspondence with minimum leaf water potential and soil moisture. The response curve of assimilation to intercellular CO2 partial pressure showed that photosynthetic metabolism was greatly depressed by long-term water deficit, with a reduction of 48% for the slope at low CO2 and of 67% for photosynthetic assimilation at high CO2, and that it played a greater role than stomata in limiting photosynthesis.