Stomatal Response to Water Stress and its Relationship to Bulk Leaf Water Status and Osmotic Adjustment in Pearl Millet (Pennisetum americanum[L.] Leeke)

A gradation, that reflects the maturity of the leaves, exists in the leaf water, osmotic and turgor potential and stomatal conductance of leaves along current and 1-year-old branches of peach. Predawn leaf water potentials of immature folded leaves were approximately 0.24 MPa lower than mature leaves under both well-watered and dry conditions. During the daytime the leaf water potential of immature leaves reflected the water potential produced by water flux for transpiration. In well- watered trees, mature and immature unfolded leaves had a solute potential at least 0.5 MPa lower than immature folded leaves, resulting in a turgor potential that was approximately 0.8 MPa higher. The turgor requirement for growth appeared to be much less than that maintained in mature leaves. As water stress developed and leaf water potentials decreased, the osmotic potential of immature folded leaves declined to the level found in mature leaves, thus maintaining turgor. In contrast, mature leaves showed little evidence of turgor maintenance. Stomatal conductance was lower in immature leaves than in fully mature leaves. With the onset of water stress, conductance of mature leaves declined to a level near that of immature leaves. Loss of turgor in mature leaves may be a major factor in early stomatal closure. It was concluded that osmotic adjustment played a role in maintenance of a leaf water status favorable for some growth in water-stressed immature peach leaves.

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Leaf Water Status in Velvetleaf under Long-term Interactions of Water Stress, Atmospheric Humidity, and Carbon Dioxide

Journal of Plant Physiology ◽

10.1016/s0176-1617(11)80377-9 ◽

1992 ◽

Vol 139 (5) ◽

pp. 600-604 ◽

Cited By ~ 5

Author(s):

Yao-Hua Luo ◽

Boyd R. Strain

Keyword(s):

Carbon Dioxide ◽

Water Stress ◽

Water Status ◽

Leaf Water ◽

Atmospheric Humidity ◽

Leaf Water Status

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Leaf Water Storage and Robustness to Intermittent Drought: A Spatially Explicit Capacitive Model for Leaf Hydraulics

Frontiers in Plant Science ◽

10.3389/fpls.2021.725995 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yongtian Luo ◽

Che-Ling Ho ◽

Brent R. Helliker ◽

Eleni Katifori

Keyword(s):

Water Stress ◽

Water Potential ◽

Environmental Changes ◽

Water Status ◽

Stomatal Closure ◽

Water Storage ◽

Leaf Water ◽

Spatially Explicit ◽

Air Humidity ◽

Leaf Water Status

Leaf hydraulic networks play an important role not only in fluid transport but also in maintaining whole-plant water status through transient environmental changes in soil-based water supply or air humidity. Both water potential and hydraulic resistance vary spatially throughout the leaf transport network, consisting of xylem, stomata and water-storage cells, and portions of the leaf areas far from the leaf base can be disproportionately disadvantaged under water stress. Besides the suppression of transpiration and reduction of water loss caused by stomatal closure, the leaf capacitance of water storage, which can also vary locally, is thought to be crucial for the maintenance of leaf water status. In order to study the fluid dynamics in these networks, we develop a spatially explicit, capacitive model which is able to capture the local spatiotemporal changes of water potential and flow rate in monocotyledonous and dicotyledonous leaves. In electrical-circuit analogs described by Ohm's law, we implement linear capacitors imitating water storage, and we present both analytical calculations of a uniform one-dimensional model and numerical simulation methods for general spatially explicit network models, and their relation to conventional lumped-element models. Calculation and simulation results are shown for the uniform model, which mimics key properties of a monocotyledonous grass leaf. We illustrate water status of a well-watered leaf, and the lowering of water potential and transpiration rate caused by excised water source or reduced air humidity. We show that the time scales of these changes under water stress are hugely affected by leaf capacitance and resistances to capacitors, in addition to stomatal resistance. Through this modeling of a grass leaf, we confirm the presence of uneven water distribution over leaf area, and also discuss the importance of considering the spatial variation of leaf hydraulic traits in plant biology.

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Leaf Water Status and Its Relationship with Reproductive Responses of Common Bean (<i>Phaseolus vulgaris</i> L.) Genotypes under Water Stress

American Journal of Plant Sciences ◽

10.4236/ajps.2014.511169 ◽

2014 ◽

Vol 05 (11) ◽

pp. 1547-1556

Author(s):

Apurba Kanti Choudhury ◽

Md Abdul Karim ◽

Md Moynul Haque ◽

Qazi Abdul Khaliq ◽

Jalal Uddin Ahmed ◽

...

Keyword(s):

Water Stress ◽

Phaseolus Vulgaris ◽

Common Bean ◽

Water Status ◽

Leaf Water ◽

Leaf Water Status

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Grazing winter wheat relieves plant water stress and transiently enhances photosynthesis

Functional Plant Biology ◽

10.1071/fp10040 ◽

2010 ◽

Vol 37 (8) ◽

pp. 726 ◽

Cited By ~ 37

Author(s):

Matthew T. Harrison ◽

Walter M. Kelman ◽

Andrew D. Moore ◽

John R. Evans

Keyword(s):

Water Stress ◽

Leaf Area ◽

Water Status ◽

Leaf Water ◽

Plant Water ◽

Rubisco Activity ◽

Leaf Water Status ◽

Area Index ◽

Plant Water Stress ◽

The Impact

To model the impact of grazing on the growth of wheat (Triticum aestivum L.), we measured photosynthesis in the field. Grazing may affect photosynthesis as a consequence of changes to leaf water status, nitrogen content per unit leaf area (Na) or photosynthetic enzyme activity. While light-saturated CO2 assimilation rates (Asat) of field-grown wheat were unchanged during grazing, Asat transiently increased by 33–68% compared with ungrazed leaves over a 2- to 4-week period after grazing ended. Grazing reduced leaf mass per unit area, increased stomatal conductance and increased intercellular CO2 concentrations (Ci) by 36–38%, 88–169% and 17–20%, respectively. Grazing did not alter Na. Using a photosynthesis model, we demonstrated that the increase in Asat after grazing required an increase in Rubisco activity of up to 53%, whereas the increase in Ci could only increase Asat by up to 13%. Increased Rubisco activity was associated with a partial alleviation of leaf water stress. We observed a 68% increase in leaf water potential of grazed plants that could be attributed to reduced leaf area index and canopy evaporative demand, as well as to increased rainfall infiltration into soil. The grazing of rain-fed grain cereals may be tailored to relieve plant water stress and enhance leaf photosynthesis.

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