Water Relations of Expanding Leaves

1986 ◽  
Vol 13 (1) ◽  
pp. 45 ◽  
Author(s):  
EWR Barlow
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Leaf Development ◽  
Leaf Growth ◽  
Water Status ◽  
Morphological Difference ◽  
Growth Patterns ◽  
Expansion Phase ◽  
Turgor Maintenance ◽  
Yield Threshold

The reactivity of leaf growth to changes in plant water status has been analysed in terms of leaf development, water transport and turgor. The different growth patterns of monocotyledonous and dicotyledonous leaves result in fundamental differences in the water relations of expanding leaves. Most monocotyledonous leaf cells complete their expansion phase within the protective older leaf bases, while the majority of dicotyledonous leaf cells expand in an exposed evaporative environment. The consequence of this morphological difference is that expanding monocotyledonous leaves behave similarly to other enclosed tissue during water stress by exhibiting turgor maintenance through osmotic adjustment. Expanding dicotyledonous leaves do not exhibit this response. The maintenance of turgor in monocotyledons in the absence of leaf expansion suggests that growth is controlled by the yield threshold of the cell wall during episodes of water stress.

scholarly journals THE EFFECTS OF WATER STRESS ON PLANT WATER STATUS AND GROWTH OF SELECTED SWEETPOTATO GENOTYPES

HortScience ◽  
1991 ◽  
Vol 26 (5) ◽  
pp. 490f-490
Author(s):  
Thammasak Thongket ◽  
James O. Garner
Keyword(s):  
Water Stress ◽  
Leaf Growth ◽  
Water Status ◽  
Leaf Size ◽  
Stress Sensitivity ◽  
Leaf Water ◽  
Genotypic Differences ◽  
Storage Roots ◽  
Diffusive Resistance ◽  
Total Growth

Responses of four sweetpotato genotypes (`Centennial', `Travis', `Vardaman' and `MS 21-2') to water stress were studied. Two irrigation regimes (irrigation vs non-irrigation) were imposed on five-week old cuttings grown in a greenhouse environment. Transpiration and leaf diffusive resistance (LDR) were measured with a steady state porometer and mid-day total leaf water potentials were determined with a thermocouple psychrometer. Leaf growth was inhibited earlier than root growth. Water stress caused a reduction of leaf size in Centennial and in leaf number in the other three. Storage root number of Vardaman was not inhibited by limited soil moisture but development of storage roots was retarded by water stress. Total growth under non-irrigation of MS 21-2 was inhibited more than Vardaman. Mid-day leaf water potential did not show promise as a good indicator of water status. Genotypic differences in the water stress sensitivity as measured by LDR, were observed.

Time Trends for Change in Osmotic Adjustment and Water Relations of Leaves of Cenchrus ciliaris During and After Water Stress

1983 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Leaf Growth ◽  
Weight Ratio ◽  
Bound Water ◽  
Arid Environment ◽  
Leaf Water ◽  
Buffel Grass

Buffel grass was subjected to a soil drying cycle for 5 weeks in a semi-arid environment. As water stress developed, the leaf water relations characteristics of these plants (Dry treatment) were compared with those of irrigated plants (Wet treatment). Leaf water potential (Ψ) of the Dry treatment measured at 1400 h decreased to a minimum of -6.9 MPa. The stressed leaves adjusted osmotically, with the osmotic potential at full turgor (Ψπ100) decreasing (becoming more negative) linearly with time (0.017 MPa day-1) and with decreasing water potential measured at 1400 h (0.11 MPa per 1 MPa decrease in Ψ). Maximum osmotic adjustment (Ψπ100 Wet -Ψπ100 Dry) was 0.66 MPa, and this change together with lower cell wall elasticity decreased by 1.03 MPa the water potential (Ψ0) at which the stressed leaves lost turgor. Differences between the stress- acclimated Dry leaves and the Wet leaves in bound water, turgid weight:dry weight ratio and the relative water content at which they reached zero turgor were small and inconsistent. At 18 days after rewatering, the Ψπ100 value of acclimated leaves was still 0.18 MPa lower than that of the control leaves. The substantial shift in Ψ0 gained the stress-acclimated leaves only one extra day before they lost turgor at 1400 h, and only 2.5 extra days before being permanently wilted. This small gain in time and the rapid cessation of leaf growth even before positive turgor was completely lost suggests that osmotic adjustment may not contribute greatly to continued leaf growth in water-stressed plants of buffel grass.

scholarly journals Water relations and leaf growth rate of three Agropyron genotypes under water stress

BIOCELL ◽  
2002 ◽  
Vol 26 (3) ◽  
pp. 309-317 ◽  
Author(s):  
MAR虯 G. GARC虯 ◽  
CARLOS A. BUSSO ◽  
PABLO POLCI ◽  
NORBERTO L. GARC虯 GIROU ◽  
VIVIANA ECHENIQUE
Keyword(s):  
Growth Rate ◽  
Water Stress ◽  
Water Relations ◽  
Leaf Growth

Water Relations of the Banana. III. Effects of Controlled Water Stress on Water Potential, Transpiration, Photosynthesis and Leaf Growth.

1990 ◽  
Vol 17 (1) ◽  
pp. 79 ◽  
Author(s):  
J Kallarackal ◽  
JA Milburn ◽  
DA Baker
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Growth ◽  
Water Status ◽  
Stomatal Closure ◽  
Leaf Temperature ◽  
Gas Exchange Parameters ◽  
Applied Water ◽  
Potential Transpiration ◽  
Exchange Parameters

Banana suckers were grown in the glasshouse under controlled environmental conditions. Water potentials were measured on plants 6-12 months old using the solute potential of the latex as a guide. The diurnal fluctuations in water potential were monitored along with measurements of transpiration rate, leaf conductance, leaf temperature, assimilation rate and leaf growth rate. Concurrent measurements were made of water potential, transpiration and other gas exchange parameters under rapidly and slowly applied water stress. Stomatal closure was almost complete after 10 days of rapid stress whereas, under slow stress, closure was delayed for a total of 30 days. Stomatal closure was accompanied by a reduction in transpiration and photosynthesis. However, the water potential of the plant was never more negative than -0.35 MPa even when the water stress was severe. The growth of the plant, as evaluated from the emergence of new leaves, was stopped at the same time as photosynthesis. The implications of these observations on the ability of banana to utilise dwindling supplies of water are discussed. The use of latex solute potential as a tool to understand the water status of the plant is further explained.

scholarly journals Identification of TCP13 as an Upstream Regulator of ATHB12 during Leaf Development

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 644 ◽  
Author(s):  
Yoon-Sun Hur ◽  
Jiyoung Kim ◽  
Sunghan Kim ◽  
Ora Son ◽  
Woo-Young Kim ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Leaf Development ◽  
Cell Expansion ◽  
Regulatory Networks ◽  
Leaf Growth ◽  
Consensus Sequence ◽  
Upstream Region ◽  
Expansion Phase ◽  
Upstream Regulator ◽  
Hybrid Screening

Leaves grow by distinct phases controlled by gene regulatory networks including many transcription factors. Arabidopsis thaliana homeobox 12 (ATHB12) promotes leaf growth especially during the cell expansion phase. In this study, we identify TCP13, a member of the TCP transcription factor family, as an upstream inhibitor of ATHB12. Yeast one-hybrid screening using a 1.2-kb upstream region of ATHB12 resulted in the isolation of TCP13 as well as other transcription factors. Transgenic plants constitutively expressing TCP13 displays a significant reduction in leaf cell size especially during the cell expansion period, while repression of TCP13 and its paralogs (TCP5 and TCP17) result in enlarged leaf cells, indicating that TCP13 and its paralogs inhibit leaf development, mainly at the cell expansion phase. Its expression pattern during leaf expansion phase is opposite to ATHB12 expression. Consistently, the expression of ATHB12 and its downstream genes decreases when TCP13 was overexpressed, and increases when the expression of TCP13 and its paralogs is repressed. In chromatin immunoprecipitation assays using TCP13-GFP plants, a fragment of the ATHB12 upstream region that contains the consensus sequence for TCP binding is strongly enriched. Taken together, these findings indicate that TCP13 and its paralogs inhibit leaf growth by repressing ATHB12 expression.

Plant Water Relations, Irrigation Management and Crop Yield

1965 ◽  
Vol 1 (3) ◽  
pp. 161-177 ◽  
Author(s):  
Ralph A. Fischer ◽  
Robert M. Hagan
Keyword(s):  
Water Stress ◽  
Crop Yield ◽  
Water Relations ◽  
Water Status ◽  
Irrigation Management ◽  
Crop Growth ◽  
Plant Water Relations ◽  
Physiological Effects ◽  
Plant Water ◽  
Water Usage

SummaryResponses of crop yield to water stress are classified on the basis of physiological considerations. Crop growth is sensitive to water stress, particularly because of the physiological effects of stress on the production and maintenance of photosynthetic tissue. Crop yield, depending on the nature of the harvested organ and the origin of its constituents, may be more or less sensitive to water stress than crop growth. In applying this information to irrigation management, there is a need for simple quantitative measures of plant water status. The problem of avoiding water stress during critical ontogenetic stages and, conversely, the possibility of using moderate water stress at certain times to improve yield and the efficiency of water usage, are discussed.

scholarly journals Leaf and Root Growth in Relation to Water Status

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 550C-550
Author(s):  
Theodore C. Hsiao
Keyword(s):  
Water Stress ◽  
Root Growth ◽  
Leaf Growth ◽  
Water Status ◽  
Turgor Pressure ◽  
High Sensitivity ◽  
Differential Sensitivity ◽  
Canopy Development ◽  
Consequent Reduction ◽  
Use Efficiency

Of all the plant processes examined, leaf growth and canopy development is the most sensitive to water stress. The consequent reduction in cumulative radiation interception by the plant leads to a smaller biomass as well as reduced transpiration, usually without altering radiation-use efficiency or water-use efficiency of the canopy. Sensitivity of leaf growth to the growth medium or aerial environment of the plant will be illustrated. A way to quantify the consequent and often marked impact on productivity will be discussed. In contrast with the high sensitivity of leaf growth to water stress, root growth is more resistant. This allows at least the partial maintenance of root growth as the stress intensifies. The result is a more thorough extraction of soil water while transpiration is restricted by the smaller leaf area. The possible mechanisms for the differential sensitivity of leaf and root growth to water stress will be evaluated. Emphasis will be placed on processes underlying cell enlargement. Recent data, obtained with the pressure microprobe that measures turgor pressure in individual cells, will be presented to illustrate the contrasting responses in growth, cell wall extending ability, and solute transport to the growing cells when the plant adjusts and accommodates to changes in water status.

Monitoring Crop Water Status and Irrigation Needs Using Multispectral Airborne Sensors

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 905D-905
Author(s):  
Thomas R. Clarke ◽  
M. Susan Moran
Keyword(s):  
Water Stress ◽  
Near Infrared ◽  
Water Status ◽  
Canopy Cover ◽  
Stress Index ◽  
Crop Water ◽  
Vegetative Cover ◽  
Crop Water Stress Index ◽  
Water Stress Index ◽  
Subsurface Drip

Water application efficiency can be improved by directly monitoring plant water status rather than depending on soil moisture measurements or modeled ET estimates. Plants receiving sufficient water through their roots have cooler leaves than those that are water-stressed, leading to the development of the Crop Water Stress Index based on hand-held infrared thermometry. Substantial error can occur in partial canopies, however, as exposed hot soil contributes to deceptively warm temperature readings. Mathematically comparing red and near-infrared reflectances provides a measure of vegetative cover, and this information was combined with thermal radiance to give a two-dimensional index capable of detecting water stress even with a low percentage of canopy cover. Thermal, red, and near-infrared images acquired over subsurface drip-irrigated cantaloupe fields demonstrated the method's ability to detect areas with clogged emitters, insufficient irrigation rate, and system water leaks.

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