Change in photosynthesis and water relations with age and season in Abiesamabilis

1984 ◽  
Vol 14 (1) ◽  
pp. 77-84 ◽  
Author(s):  
R. O. Teskey ◽  
C. C. Grier ◽  
T. M. Hinckley
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Relations ◽  
Net Photosynthesis ◽  
Carbon Gain ◽  
Xylem Water Potential ◽  
Needle Age ◽  
Stressful Environment ◽  
Competitive Success ◽  
One Year

Seasonal changes in water relations and net photosynthesis were measured over a year in current and 1-year-old foliage of Abiesamabilis (Dougl.) Forbes, a subalpine conifer. Responses were compared with maximum rates achieved in older foliage. Current-year foliage developed slowly during the growing season. Although growth began on 22 June, highest rates of stomatal conductance and net photosynthesis did not occur until September and October. One-year-old foliage had the highest rates of net photosynthesis (12.9 mg CO2•dm−2•h−1) and stomatal conductance (3.1 mm•s−1) during the summer. Net photosynthesis decreased with needle age, but foliage as old as 7 years had rates of net photosynthesis as high as 5.0 mg CO2•dm−2•h−1. There was no evidence of photosynthetic adjustment to seasonal change in temperature. The optimum temperature for photosynthesis remained at 15 ± 1.5 °C throughout the year. No water stress was observed during the summer. Xylem water potential never decreased below −1.65 MPa and was always well above the turgor loss point. The lack of any apparent water stress, combined with photosynthetic characteristics, indicated that summer was the most important season for carbon gain. These results also suggested that a strategy for competitive success by Abiesamabilis in this cold, stressful environment is minimum dependence on the carbon gain of any individual age-class of foliage. Instead trees rely on the combined photosynthetic capacity of many years of foliage.

Response to water stress of Italian alder seedlings from diverse geographic origins

1989 ◽  
Vol 19 (8) ◽  
pp. 1071-1076 ◽  
Author(s):  
M. Borghetti ◽  
S. Cocco ◽  
M. Lambardi ◽  
S. Raddi
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Leaf Area ◽  
Water Status ◽  
Net Photosynthesis ◽  
Severe Drought ◽  
Xylem Water Potential ◽  
Drought Treatment ◽  
Internal Water ◽  
Response To Water

The morphological and physiological response to water stress was studied in 2-year-old potted Italian alder (Alnuscordata Loisel.) seedlings. Leaf area, transpiration, stomatal conductance, and xylem water potential were measured during May 1987 on seedlings from five geographic sources grown (i) with soil water content close to field capacity and (ii) with a severe drought. Significant differences in leaf area were found, at the end of the experiment, between drought-stressed and well-watered plants. As drought progressed, plants displayed a reduction of xylem water potentials and a decrease in stomatal conductance. However, transpiration did not stop completely, and seedlings were not able to maintain a favourable internal water status. Osmotic potentials for the undiluted cell sap, estimated from pressure–volume curves, were between −0.9 and −1.3 MPa. In June 1988, a similar experiment was carried out using seedlings from only one geographic source. A simultaneous decrease of transpiration, xylem potential, and net photosynthesis was observed in seedlings subjected to the drought treatment. During both experiments, a recovery of physiological parameters was observed, after rewatering. Some differences between provenances were detected. The provenance from Corsica showed the greatest sensitivity to water stress; a seed source from the province of Avellino (Campania, south Italy) was able to maintain a more favourable internal water status, as drought progressed.

scholarly journals Optimizing stomatal conductance for maximum carbon gain under water stress: a meta-analysis across plant functional types and climates

2011 ◽  
Vol 25 (3) ◽  
pp. 456-467 ◽  
Author(s):  
Stefano Manzoni ◽  
Giulia Vico ◽  
Gabriel Katul ◽  
Philip A. Fay ◽  
Wayne Polley ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Meta Analysis ◽  
Plant Functional Types ◽  
Carbon Gain ◽  
Functional Types

Water stress preconditioning of black spruce seedlings from lowland and upland sites

1994 ◽  
Vol 72 (10) ◽  
pp. 1511-1518 ◽  
Author(s):  
Abdenbi Zine El Abidine ◽  
Pierre Y. Bernier ◽  
James D. Stewart ◽  
André P. Plamondon
Keyword(s):  
Water Relations ◽  
Black Spruce ◽  
Sugar Content ◽  
Net Photosynthesis ◽  
Soil Drought ◽  
Drought Period ◽  
Gas Exchanges ◽  
Total Sugar Content ◽  
Net Photosynthesis Rate ◽  
One Year

One-year-old seedlings from two pairs of upland – lowland populations were subjected to three cycles of drought preconditioning. During a subsequent fourth cycle, preconditioned seedlings and seedlings that had been maintained under well-watered conditions were subjected to a final soil drought. During the drought periods, small but significant differences in gas exchanges and water relations were observed between upland and lowland seedlings but the differences were not consistent either within each lowland – upland pair or over the four cycles. During the final drought period, preconditioned seedlings maintained significantly higher net photosynthesis rate, stomatal conductance, and transpiration rate than unconditioned seedlings. In contrast, no significant differences were found in midday water potential, total sugar content, or water relations parameters between preconditioned and unconditioned seedlings. The results suggest an absence of ecotypic variation with respect to drought tolerance in black spruce. They also suggest that preconditioning in black spruce seedlings occurs mostly through the acclimation of stomatal and photosynthetic mechanisms to drought, without active osmotic adjustment. Key words: Picea mariana, ecotype, gas exchanges, water relations, osmoregulation, preconditioning.

scholarly journals Uso da subirrigação para imposição de estresse hídrico em sistema semi-contínuo para medição de CO2

2015 ◽  
Vol 21 (2) ◽  
pp. 235 ◽  
Author(s):  
Rhuanito Soranz Ferrarezi ◽  
Marc W. Van Iersel ◽  
Roberto Testezlaf
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Carbon Gain ◽  
Growth Responses ◽  
Shoot Height ◽  
Soil Moisture Sensors

The objectives of this work were to evaluate the effects of distinct moisture contents to trigger subirrigation on salvia photosynthesis and plant growth, and to verify the feasibility of subirrigation use in water stress imposition research in this crop. We evaluated two substrate volumetric water contents (VWC) as treatments (0.2 and 0.4 m3 m-3) to trigger subirrigation, with 4 replications. Each replication was composed of 10 plants. An automated semi-continuous multi-chamber crop CO2-exchange system was used, with capacitance soil moisture sensors for continuous moisture monitoring. Manual subirrigation with nutrient solution was performed when VWC dropped below the thresholds. In both treatments, the values of net photosynthesis, daily carbon gain and carbon use efficiency reduced over time, from 2 to 1.1 μmol s-1 from 2.2 to 1 μmol d-1 from 0.7 to 0.45 mol mol-1, respectively, in both soil moisture treatments. Total shoot dry mass (p=0.0129), shoot height in the tip of the highest flower (p<0.0001) and total leaf area (p=0.0007) were statistically higher at 0.4 m3 m-3 treatment. The subirrigation system was not efficient to impose water stress, due to excessive variation on VWC values after each irrigation event in both treatments. Higher soil moisture promoted positive plant growth responses in salvia cultivated by subirrigation.

scholarly journals Gas exchanges of melon under water stress in the Submedium region of the São Francisco River Valley

2019 ◽  
Vol 41 (1) ◽  
pp. 42686 ◽  
Author(s):  
Daniel Vieira Amorim ◽  
Alessandro Carlos Mesquita ◽  
Lígia Borges Marinho ◽  
Vanuza De Souza ◽  
Saulo De Tarso Aidar ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Dry Matter ◽  
Block Design ◽  
Net Photosynthesis ◽  
River Valley ◽  
Sao Francisco River ◽  
Randomized Block Design ◽  
São Francisco River ◽  
Current Scenario

The current scenario of increased water scarcity is due to climate change and directly affects food production. It is thus necessary to develop strategies to mitigate the impacts of low water availability. Therefore, the goal of the present study is to evaluate the physiological behaviour of melon cultivars under water stress. The experiment was conducted in a protected environment in the experimental Submedium region of the São Francisco River Valley in the period ranging from October to December. In this study, we used the melon cultivars 'Amarelo' and 'Piel de Sapo'. The experiment was conducted in a randomized block design with three replicates that were subdivided into plots, where the plots were comprised of four irrigation rates (50, 75, 100, and 125% of crop evapotranspiration – CET), subplots were comprised of the two melon cultivars, and sub-subplots were comprised of samplings for physiological analyses (15, 30, and 45 days after transplanting). The parameters evaluated were stomatal conductance, transpiration, net photosynthesis, relationship CI/CA, and accumulated dry matter. Water stress reduced the stomatal conductance, transpiration, net photosynthesis, CI/CA, and accumulated dry matter. 'Piel de Sapo' showed a higher photosynthetic adjustment than 'Amarelo' melon due to the gas exchange behaviour of the former, and it was, therefore, more tolerant to water stress.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCOA (THEOBROMA CACAO L.): A REVIEW

2011 ◽  
Vol 47 (4) ◽  
pp. 653-676 ◽  
Author(s):  
M. K. V. CARR ◽  
G. LOCKWOOD
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Use ◽  
Water Relations ◽  
Stomatal Closure ◽  
Dry Season ◽  
Leaf Water ◽  
Background Information ◽  
Published Data ◽  
Rhythmic Pattern

SUMMARYThe results of research into the water relations of cocoa are reviewed in the context of drought mitigation and irrigation need. Background information on the centres of production of the cocoa tree, and the role of water in crop development and growth processes, is followed by reviews of the effects of water stress on stomatal conductance, leaf water status and gas exchange, together with drought tolerance, crop water use and water productivity. Leaf and shoot growth occur in a series of flushes, which are synchronized by the start of the rains following a dry season (or an increase in temperature), alternating with periods of ‘dormancy’. Flowering is inhibited by water stress but synchronous flowering occurs soon after the dry season ends. Roots too grow in a rhythmic pattern similar to that of leaf flushes. Roots can reach depths of 1.5–2.0 m, but with a mass of roots in the top 0.2–0.4 m, and spread laterally >5 m from the stem. Stomata open in low light intensities and remain fully open in full sunlight in well-watered plants. Partial stomatal closure begins at a leaf water potential of about −1.5 MPa. Stomatal conductance is sensitive to dry air, declining as the saturation deficit increases from about 1.0 up to 3.5 kPa. Net photosynthesis and transpiration both consequently decline over a similar range of values. Little has been published on the actual water use of cocoa in the field. Measured ETc values equate to <2 mm d−1 only, whereas computed ETc rates of 3–6 mm d−1 in the rains and <2 mm d−1 in the dry season have also been reported. Despite its sensitivity to water stress, there is too a paucity of reliable, field-based published data of practical value on the yield responses of cocoa to drought or to irrigation. With the threat of climate change leading to less, or more erratic, rainfall in the tropics, uncertainty in yield forecasting as a result of water stress will increase. Social, technical and economic issues influencing the research agenda are discussed.

Evidence for nonstomatal inhibition of net photosynthesis in rapidly dehydrated shoots of Populus

1986 ◽  
Vol 16 (6) ◽  
pp. 1371-1375 ◽  
Author(s):  
G. Scarascia-Mugnozza ◽  
T. M. Hinckley ◽  
R. F. Stettler
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Net Photosynthesis ◽  
Volume Shrinkage ◽  
Sharp Reduction ◽  
Stomatal Behaviour ◽  
Net Assimilation ◽  
Protoplast Volume

Results are presented on the decline of net photosynthesis during the application of rapid water stress to excised shoots of different Populus L. clones. Six clones were selected from the species Populustrichocarpa Torr. & Gray, Populusdeltoides Bartr., and from the hybrid Populustrichocarpa × Populusdeltoides, taking into account the differences in stomatal behaviour between and within these species. The two most productive P. trichocarpa clones and the hybrid clone, characterized by a reduced ability to close stomata during leaf desiccation, showed, nevertheless, a sharp reduction of net photosynthesis at water potentials lower than −1.5 MPa. In contrast, the inhibition of net assimilation in the P. deltoides clone, caused by water stress, was accompanied by a reduction in stomatal conductance. In all studied clones the decrease in net photosynthetic rate followed closely the point of turgor loss of the leaves, indicating a possible relationship between nonstomatal inhibition of photosynthesis and protoplast volume shrinkage.

The control of Phytophthora root rot of avocado with fungicides and the effect of this disease on water relations, yield and ring neck.

1986 ◽  
Vol 26 (2) ◽  
pp. 249 ◽  
Author(s):  
AW Whiley ◽  
KG Pegg ◽  
JB Saranah ◽  
LI Forsberg
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Complete Recovery ◽  
Xylem Water Potential ◽  
Physiological Disorder ◽  
Phytophthora Root Rot ◽  
Water Sprays

Avocado trees (cv. Fuerte) were protected from root rot caused by Phytophthora cinnamomi by foliar metalaxyl. Protected trees had higher xylem water sprays with phosethyl-A1 or soil applications of potentials and showed faster and more complete recovery from water stress during the evening than un treated root rot affected trees. protected trees had greater fruit yields and there was a correlation between the incidence of the physiological disorder ring neck and xylem water potential in trees.

CO2 and water vapor exchange of Pinustaeda in relation to stomatal behavior: test of an optimization hypothesis

1988 ◽  
Vol 18 (2) ◽  
pp. 150-157 ◽  
Author(s):  
J. A. Fites ◽  
R. O. Teskey
Keyword(s):  
Water Vapor ◽  
Stomatal Conductance ◽  
Absolute Humidity ◽  
Net Photosynthesis ◽  
High Irradiance ◽  
Carbon Gain ◽  
Gain Ratio ◽  
Stomatal Behavior ◽  
Diurnal Patterns ◽  
Behavior Test

Responses of CO2 and water vapor exchange to absolute humidity deficit (AHD) were measured for seedlings of Pinustaeda L. at high and low irradiance in the laboratory. Diurnal patterns of CO2 and water vapor exchange of P. taeda seedlings and trees were monitored in the field. Stomatal behavior was evaluated in relation to a recent hypothesis of "optimal" stomatal behavior, in which changes in stomatal conductance in response to environmental variation are such that water loss is minimized for a given amount of carbon gain. That is, when stomatal behavior is "optimal," the ratio (gain ratio) of the sensitivities of transpiration and net photosynthesis to changes in stomatal conductance [Formula: see text] is constant.Laboratory and field stomatal behavior generally did not conform with this hypothesis. Under controlled conditions, at high irradiance, the gain ratio increased with AHD. In the field, the gain ratio increased diurnally on most days. Increasing gain ratios were associated with increasing [Formula: see text] values but relatively uniform [Formula: see text] values. Uniform gain ratios in the field were observed on some days, associated with uniform environment, constant [Formula: see text], or varying [Formula: see text] values.

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