scholarly journals Leaf Water Relations in Lime Trees Grown under Shade Netting and Open-Air

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 510 ◽  
Author(s):  
Ana Belén Mira-García ◽  
Wenceslao Conejero ◽  
Juan Vera ◽  
María Carmen Ruiz-Sánchez
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Canopy Temperature ◽  
Net Photosynthesis ◽  
Irrigation Scheduling ◽  
Plant Water Status ◽  
Plant Water ◽  
Stem Water Potential ◽  
Thermal Index

Physiological plant water status indicators are useful for managing precision irrigation in regions with limited water resources. The aim of this work was to evaluate the effect of shade netting on the diurnal and seasonal variations of several plant water status indicators in young lime trees (Citrus latifolia Tan., cv. Bearss), grown at the CEBAS-CSIC experimental station in Murcia, Spain. Stem water potential (Ψstem), leaf gas exchange (net photosynthesis (Pn) and stomatal conductance (gs)), and canopy temperature (Tc) were measured on representative days of winter and summer. The Ψstem daily pattern was quite similar in both seasons under both conditions. However, the circadian rhythm of leaf gas exchange was affected by shade conditions, especially in summer, when shaded leaves showed maximum gs values for a longer time, allowing higher net photosynthesis (37%). Canopy temperature behaved similarly in both conditions, nevertheless, lower values were recorded in open-air than in shaded trees in the two seasons. The canopy-to-air temperature difference (Tc − Ta), however, was lower in shaded trees during the daylight hours, indicating the higher degree of leaf cooling that was facilitated by high gs values. The possibility of continuously recording Tc makes it (or the proposed canopy thermal index, CTI) a promising index for precise irrigation scheduling. Shade netting was seen to favour gas exchange, suggesting that it may be considered alternative to open-air for use in semi-arid areas threatened by climate change.

scholarly journals Microtensiometers Accurately Measure Stem Water Potential in Woody Perennials

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2780
Author(s):  
Victor Blanco ◽  
Lee Kalcsits
Keyword(s):  
Water Potential ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Full Range ◽  
Canopy Temperature ◽  
Plant Water ◽  
Stem Water Potential ◽  
Woody Tissue ◽  
Woody Perennials ◽  
Stem Water

Stem water potential (Ψstem) is considered to be the standard measure of plant water status. However, it is measured with the pressure chamber (PC), an equipment that can neither provide continuous information nor be automated, limiting its use. Recent developments of microtensiometers (MT; FloraPulse sensors), which can continuously measure water tension in woody tissue of the trunk of the tree, can potentially highlight the dynamic nature of plant water relations. Thus, this study aimed to validate and assess the usefulness of the MT by comparing the Ψstem provided by MT with those same measurements from the PC. Here, two irrigation treatments (a control and a deficit treatment) were applied in a pear (Pyrus communis L.) orchard in Washington State (USA) to capture the full range of water potentials in this environment. Discrete measurements of leaf gas exchange, canopy temperature and Ψstem measured with PC and MT were made every two hours for four days from dawn to sunset. There were strong linear relationships between the Ψstem-MT and Ψstem-PC (R2 > 0.8) and with vapor pressure deficit (R2 > 0.7). However, Ψstem-MT was more variable and lower than Ψstem-PC when Ψstem-MT was below −1.5 MPa, especially during the evening. Minimum Ψstem-MT occurred later in the afternoon compared to Ψstem-PC. Ψstem showed similar sensitivity and coefficients of variation for both PC and MT acquired data. Overall, the promising results achieved indicated the potential for MT to be used to continuously assess tree water status.

Relationship of plant water status and leaf gas exchange with fruit cracking of pomegranate

2019 ◽  
Vol 76 (2) ◽  
pp. 289
Author(s):  
Akath Singh ◽  
U. Burman ◽  
P. Santra ◽  
Anurag Saxena ◽  
P.R. Meghwal
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Plant Water Status ◽  
Plant Water ◽  
Fruit Cracking ◽  
Relationship Of

scholarly journals An Index for User-Friendly Proximal Detection of Water Requirements to Optimized Irrigation Management in Vineyards

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 323
Author(s):  
Ana Fernandes de Oliveira ◽  
Massimiliano Giuseppe Mameli ◽  
Mauro Lo Cascio ◽  
Costantino Sirca ◽  
Daniela Satta
Keyword(s):  
Water Potential ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Water Productivity ◽  
Linear Regression Analysis ◽  
Plant Water Status ◽  
Plant Water ◽  
Stem Water Potential ◽  
Water Requirements ◽  
Stem Water

We propose an index for proximal detection of water requirements to optimize the use of water resources in arid and semi-arid wine growing regions. To test the accuracy and representativeness of the proposed irrigation need index (IIN), plant water status and physiological performances were monitored during seasons 2019 and 2020 in two grapevine varieties with different anisohydric degree (Vermentino and Cannonau) grown in 3 sites in Sardinia (Italy). Daily leaf gas exchange curves and stem water potential were recorded. Canopy temperature was monitored, using both thermistor sensors (Tc) and infrared thermometry (IR). Meteorological data, including dry and wet bulb temperatures were collected to compute and parametrize IIN, based on energy balance equation. Vineyard water balance, thermal time and irrigation water productivity were characterized. Linear regression analysis allowed to validate IIN for both varieties and to establish target thresholds for mild, moderate and severe water deficit to optimize irrigation for high yield and quality objectives. IIN well represents plant water status, using either Tc or IR, and allows rapid and easy detection of water and heat stress condition, even when a stricter stomatal control determines slighter variation and lower response of stem water potential, as in plants with low anisohydric degree.

scholarly journals Irrigation Factor Approach Based on Soil Water Content: A Nectarine Orchard Case Study

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 589 ◽  
Author(s):  
Juan Vera ◽  
Wenceslao Conejero ◽  
María Conesa ◽  
M. Ruiz-Sánchez
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Precision Agriculture ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Plant Water Status ◽  
Plant Water ◽  
Stem Water Potential ◽  
Water Requirements ◽  
Irrigation Drainage

Precision agriculture requires irrigation supported by an accurate knowledge of the crop water requirements. In this paper, a novel approach for drip irrigation scheduling of fruit trees is presented based on the results obtained during a full growing season in an early-maturing nectarine orchard growing in a clay loam soil in a Mediterranean environment. Real-time water content was monitored in the soil profile of the main root exploration zone by means of capacitance probes; in addition, plant water status (midday stem water potential and leaf gas exchange) and canopy development were frequently measured throughout the vegetative cycle. The reference evapotranspiration (ET0) values, taken from a nearby automatic meteorological station, and the measured irrigation values allowed the determination of the irrigation factors once irrigation drainage during the season was assumed to be negligible and plant water status was proved to be adequate. The proposed irrigation factors offer a hands-on approach as an easy tool for irrigation management based on suitable soil water deficits, allowing the water requirements of nectarine trees under precision irrigation to be determined in semi-arid agrosystems where water resources are limited.

scholarly journals Midday Stem Water Potential Values Needed to Maintain Photosynthesis and Leaf Gas Exchange Established for Pecan

2014 ◽  
Vol 139 (5) ◽  
pp. 537-546 ◽  
Author(s):  
Yahia Othman ◽  
Dawn VanLeeuwen ◽  
Richard Heerema ◽  
Rolston St. Hilaire
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Stem Water Potential ◽  
Flood Irrigation ◽  
Dry Down ◽  
Stem Water ◽  
The Impact

Demand for New Mexico’s limited water resources coupled with periodic drought has increased the necessity for tree water status monitoring to guide irrigation scheduling of pecan (Carya illinoinensis) orchards. The objectives of this study were to assess the impact of water status developed during the flood irrigation dry-down cycles on photosynthesis (Pn), and gas exchange [stomatal conductance (gS) to H2O (gH2O), transpiration (E), and intercellular CO2 (ci)] and to establish values of midday stem water potential (Ψsmd) that are needed to maintain Pn and gas exchange of pecan. We conducted the study simultaneously on two southern New Mexico mature pecan orchards from 2011 through 2013. Flood irrigation as determined by grower practice was used on both orchards and Pn, gH2O, E, and ci were assessed at Ψsmd of –0.4 to –2.0 MPa. Photosynthesis and gas exchange were higher in pecan trees shortly after irrigation than trees exhibiting water deficit near the end of a flood irrigation dry-down cycle. The decline in Pn was markedly noticeable when Ψsmd dropped below –0.9 MPa. We attributed the reduction in Pn mostly to stomatal limitation. The decline in Pn and gH2O exceeded 50% when Ψsmd ranged from –1.5 to –2.0 MPa. For those reasons, we recommended that pecan orchards be maintained at Ψsmd higher than –0.90 MPa to prevent significant reductions in carbon assimilation and gas exchange.

scholarly journals Effects of Trunk-shaker Harvester and Ethephon on Plant Water Status, Leaf Gas Exchange, and Yield of Citrus Cultivated under Mediterranean Conditions

HortScience ◽  
2016 ◽  
Vol 51 (7) ◽  
pp. 861-872
Author(s):  
Rosana Moreno ◽  
Diego S. Intrigliolo ◽  
Carlos Ballester ◽  
Cruz Garcerá ◽  
Enrique Moltó ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Fruit Yield ◽  
Plant Water Status ◽  
Plant Water ◽  
Current Season ◽  
Orange Trees ◽  
Time Of Harvest ◽  
Mediterranean Conditions

This work was aimed to study whether the application of ethephon as an abscission agent and mechanical harvest using a trunk shaker have any effect on plant water status, leaf gas exchange, and yield of mandarin and orange trees cultivated under Mediterranean conditions. The experiment was performed from 2008 to 2011 in five commercial orchards where parameters related to the plant water status and leaf gas exchange were measured before the application of ethephon, at harvest time and at different occasions after harvest. In addition, the effects of ethephon dose on yield in the current and subsequent seasons were also evaluated. Results showed that ethephon applications and mechanical harvest did not detrimentally affect plant water status in any of the cultivars studied. Furthermore, either had no effect or had a short temporal decrease effect on leaf gas exchange depending on the cultivar studied although with no consequences for the fruit yield obtained during the current season. Increasing ethephon doses led to fruit yield reductions in the mandarin ‘Orogrande’ trees in subsequent seasons. When trunk-shaker and ethephon applications were combined, however, yields from the late-maturing orange significantly decline in subsequent seasons. Overall, results show that using a trunk shaker is a viable technique to mechanically harvest citrus trees destined to both fresh and industry market and can be considered as an alternative to the traditional manual harvest usually performed under Mediterranean conditions. However, its use cannot be recommended for late-maturing oranges, such as the ‘Navel Lane Late’ in which mature fruit and fruitlets coexist in the tree at the time of harvest.

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