The responses of stomata and leaf gas exchange to vapour pressure deficits and soil water content

Lime tree growing area is increasing in Mediterranean temperate regions. In these areas, climate change scenario is expected to raise air temperature and water shortages. Such scenario requires new approaches to implement a precision irrigation in agriculture. In order to use water more efficiently, it becomes necessary to accurately determining the crop water needs, which are estimated by crop evapotranspiration computations (ETc). In this study the ETc of young lime trees grown under Mediterranean conditions were determined using the soil water balance method. For this purpose, two-year old lime trees (Citrus latifolia Tan., cv. Bearss) grafted on C. macrophylla rootstock were cultivated in pot-lysimeters, equipped with capacitance and granular matric sensors for real-time monitoring of the soil water status. Irrigation, drainage, and pot weight were also monitored continuously. All measurements were integrated into a telemetry platform. Agro-meteorological variables, plant water status (stem (&#936;stem) and leaf (&#936;leaf) water potentials), and leaf gas exchange parameters (stomatal conductance (gs) and net photosynthesis (Pn)) were measured. Along the experiment, an automated irrigation protocol based on volumetric soil water content (&#952;v) threshold values were programmed, guaranteeing an adequate lime tree water status. Irrigation dose was calculated based on a feed-back strategy maintaining &#952;v within 30% management allowed depletion.During the experimental period, the lime trees were well irrigated as revealed midday &#936;stem values that were maintained above -0.8 MPa. Also, the mean seasonal values of &#8776; 7 &#181;mol m&#8722;2 s&#8722;1 and 80 mmol m&#8722;2 s&#8722;1, for Pn and gs, respectively, indicated optimal gas exchange values. The computed water balance parameters yielded values for the crop evapotranspiration from 0.25to 2.56 mm day-1, in winter and summer months, respectively, with maximum values in July when evaporative demand conditions were the highest. This soil water balance was daily validated by the pot weight balance through the year.In conclusion, the automated irrigation of young potted lime trees, using soil water content as a control system variable, has ensured an adequate lime tree water status. A simple, robust weighing/drainage lysimeter, with real-time monitoring of the soil water balance parameters, has been proved practical and economical tool for crop evapotranspiration measurements.Acknowledgments: This work was funded by Spanish Agencia Estatal de Investigaci&#243;n (PID2019-106226RB-C2-1/AEI/10.13039/501100011033) and Fundaci&#243;n S&#233;neca, Regi&#243;n de Murcia (19903/GERM/15) projects.

Download Full-text

Soil apparent electrical conductivity and must carbon isotope ratio provide indication of plant water status in wine grape vineyards

Precision Agriculture ◽

10.1007/s11119-021-09787-x ◽

2021 ◽

Author(s):

Runze Yu ◽

Daniele Zaccaria ◽

Isaya Kisekka ◽

S. Kaan Kurtural

Keyword(s):

Electrical Conductivity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Leaf Gas Exchange ◽

Water Status ◽

Carbon Isotope Ratio ◽

Plant Water Status ◽

Plant Water ◽

Relative Importance

AbstractProximal sensing is being integrated into vineyard management as it provides rapid assessments of spatial variability of soils’ and plants’ features. The electromagnetic induction (EMI) technology is used to measure soil apparent electrical conductivity (ECa) with proximal sensing and enables to appraise soil characteristics and their possible effects on plant physiological responses. This study was conducted in a micro irrigated Cabernet Sauvignon (Vitis vinifera L.) vineyard to investigate the technical feasibility of appraising plant water status and its spatial variability using soil ECa and must carbon isotope ratio analysis (δ13C). Soil temperature and soil water content were monitored in-situ using time domain reflectometry (TDR) sensors. Soil ECa was measured with EMI at two depths [0–1.5 m (deep ECa) and 0–0.75 m (shallow ECa)] over the course of the crop season to capture the temporal dynamics and changes. At the study site, the main physical and chemical soil characteristics, i.e. soil texture, gravel, pore water electrical conductivity (ECe), organic carbon, and soil water content at field capacity, were determined from samples collected auguring the soil at equidistant points that were identified using a regular grid. Midday stem water potential (Ψstem) and leaf gas exchange, including stomatal conductance (gs), net carbon assimilation (An), and intrinsic water use efficiency (WUEi) were measured periodically in the vineyard. The δ13C of produced musts was measured at harvest. The results indicated that soil water content (relative importance = 24%) and texture (silt: relative importance = 22.4% and clay: relative importance = 18.2%) were contributing the most towards soil ECa. Deep soil ECa was directly related to Ψstem (r2 = 0.7214) and gs (r2 = 0.5007). Likewise, δ13C of must was directly related to Ψstem (r2 = 0.9127), gs (r2 = 0.6985), and An (r2 = 0.5693). Results from this work provided relevant information on the possibility of using spatial soil ECa sensing and δ13C analysis to infer plant water status and leaf gas exchange in micro irrigated vineyards.

Download Full-text

Effects of vapour pressure deficit and soil water content on leaf water potential between selected provenances of Eucalyptus microtheca in an irrigated plantation, eastern Kenya.

Silva Fennica ◽

10.14214/sf.a9209 ◽

1995 ◽

Vol 29 (3) ◽

Cited By ~ 5

Author(s):

Kari Tuomela ◽

Markku Kanninen

Keyword(s):

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Leaf Water Potential ◽

Vapour Pressure ◽

Vapour Pressure Deficit ◽

Leaf Water ◽

Eucalyptus Microtheca

Download Full-text

Response of wheat canopy CO2 and water gas-exchange to soil water content under ambient and elevated CO2

Global Change Biology ◽

10.1046/j.1354-1013.2001.00431.x ◽

2001 ◽

Vol 7 (5) ◽

pp. 599-611 ◽

Cited By ~ 20

Author(s):

Rowan A. C. Mitchell ◽

Valerie J. Mitchell ◽

David W. Lawlor

Keyword(s):

Gas Exchange ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Elevated Co2 ◽

Water Gas

Download Full-text

Soil apparent electrical conductivity and must carbon isotope ratio provide indication of plant water status in wine grape vineyards

10.5194/egusphere-egu21-8472 ◽

2021 ◽

Author(s):

Sahap Kurtural ◽

Runze Yu ◽

Daniele Zaccaria

Keyword(s):

Electrical Conductivity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Leaf Gas Exchange ◽

Water Status ◽

Carbon Isotope Ratio ◽

Plant Water Status ◽

Plant Water ◽

Relative Importance

Proximal sensing is being integrated into vineyard management as it provides rapid assessments of spatial variability of soils&#8217; and plants&#8217; features. The electromagnetic induction (EMI) technology is used to measure soil apparent electrical conductivity (ECa) with proximal sensing and enables to appraise soil characteristics and their possible effects on plant physiological responses. This study was conducted in a micro irrigated Cabernet Sauvignon (Vitis vinifera L.) vineyard to investigate the technical feasibility of appraising plant water status and its spatial variability using soil ECa and must carbon isotope ratio analysis (&#948;13C). Soil temperature and soil water content were monitored in-situ using time domain reflectometry (TDR) sensors. Soil ECa was measured with EMI at two depths [0 &#8211; 1.5 m (deep ECa) and 0 &#8211; 0.75 m (shallow ECa)] over the course of the crop season to capture the temporal dynamics and changes. At the study site, the main physical and chemical soil characteristics, i.e. soil texture, gravel, pore water electrical conductivity (ECe), organic carbon, and soil water content at field capacity, were determined from samples collected auguring the soil at equidistant points that were identified using a regular grid. Midday stem water potential (&#936;stem) and leaf gas exchange, including stomatal conductance (gs), net carbon assimilation (An), and intrinsic water use efficiency (WUEi) were measured periodically in the vineyard. The &#948;13C of produced musts was measured at harvest. The results indicated that soil water content (relative importance = 24 %) and texture (silt: relative importance = 22.4 % and clay: relative importance = 18.2 %) were contributing the most towards soil ECa. Deep soil ECa was directly related to &#936;stem (r2 = 0.7214) and gs (r2 = 0.5007). Likewise, &#948;13C of must was directly related to &#936;stem (r2 = 0.9127), gs (r2 = 0.6985), and An (r2 = 0.5693). Results from this work provided relevant information on the possibility of using spatial soil ECa sensing and &#948;13C analysis to infer plant water status and leaf gas exchange in micro irrigated vineyards.

Download Full-text

Stomatal and Cuticular Transpiration of Greenhouse Tomato Plants in Response to High Solution Electrical Conductivity and Low Soil Water Content

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.120.3.417 ◽

1995 ◽

Vol 120 (3) ◽

pp. 417-422 ◽

Cited By ~ 16

Author(s):

Hui-lian Xu ◽

Laurent Gauthier ◽

André Gosselin

Keyword(s):

Electrical Conductivity ◽

Gas Exchange ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Stomatal Closure ◽

Tomato Plants ◽

Cuticular Transpiration ◽

Decline Curve ◽

Gas Exchange System

`Capello' tomato plants (Lycopersicon esculentum Mill.) were grown in a greenhouse in peat-based substrate (70% sphagnum peat and 309'. perlite, by volume) and supplied with nutrient solutions of high (4.5 mS·cm-1) or low (2.3 mS·cm-1) electrical conductivity (EC) under high (95% ± 5%) or low (55% ± 8% of capillary capacity) soil water conditions. Three weeks after treatments started, stomatal transpiration (TRst) and cuticular transpiration (TRcu) rates were measured by three methods: 1) analyzing TRst and TRcu from a water retention curve obtained by drying excised leaves in air under a photosynthetic photon flux (PPF) of 400 μmol·m-1·s-1, 2) analyzing TRst and TRcu from a transpiration decline curve obtained by measuring transpiration rates after cutting the leaf from the stem of the dehydrated plant in the gas-exchange system, and 3) measuring transpiration rates under light and in dark respectively using the gas-exchange method. TRst and TRcu were decreased by high EC and/or low soil water content. For method 1, the transpiration decline curve shows two distinct phases: the initial steep slope that indicates TRst and the gently sloped section that indicates TRcu. Both slopes were lower for high EC and/or water-stressed plants compared to the control (low EC and high soil water content). The tangent lines of these two phases of the curve intersect at one point (t, w). The value oft that indicates the time for stomatal closure was longer and the value of w that indicates the critical tissue water level for stomatal closure was lower for high EC and/or water-stressed plants. In method 2, the initial rate of total transpiration was higher in high EC and/or water-stressed plants. Leaf wax content increased, especially under high EC stress. This suggests that increased deposition of wax prevents water loss from the cuticle. A delay in complete stomatal closure, complete closure at lower RWC, and reduced TRcu or an increase in wax deposit were adaptations to water and salinity stresses in tomato plants under our controlled environmental conditions.

Download Full-text