scholarly journals COMPARATIVE DROUGHT RESISTANCE AMONG SIX BIRCH (BETULA) SPECIES

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1143f-1143
Author(s):  
Thomas G. Ranney ◽  
R.E. Bir ◽  
W.A. Skroch
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Leaf Gas Exchange ◽  
Leaf Water ◽  
Mild Stress ◽  
Turgor Loss Point ◽  
Leaf Osmotic Potential ◽  
Response To Water

In order to evaluate and compare adaptability to dry sites, plant water relations and leaf gas exchange were compared in response to water stress among six birch species: monarch birch (Betula maximowicziana), river birch (B. nigra), paper birch (B. papyrifera), European birch (B. pendula), `Whitespire' Japanese birch (B. platyphylla var. japonica `Whitespire'), and gray birch (B. pendula). After 28 days without irrigation, Japanese birch maintained significantly higher stomatal conductance (gs) and net photosynthesis (Pn) than did any of the other species, despite having one of the lowest mid-day water potentials. Evaluation of tissue water relations, using pressure-volume methodology, showed no evidence of osmotic adjustment for any of these species in response to water stress. However, there was substantial variation among species in the water potential at the turgor loss point; varying from a high of -1.34 MPa for river birch to a low of -1.78 MPa for Japanese birch. Rates of Pn and gs under mild stress (mean predawn leaf water potential of -0.61 MPa) were negatively correlated with leaf osmotic potential at full turgor and the leaf water potential at the turgor loss point.

scholarly journals Leaf Physiological Responses to Drought Stress and Community Assembly in an Asian Savanna

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1119
Author(s):  
Thuy T. Nguyen ◽  
Stefan K. Arndt ◽  
Patrick J. Baker
Keyword(s):  
Drought Stress ◽  
Southeast Asia ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Forest Type ◽  
Adaptive Strategies ◽  
Leaf Water ◽  
Turgor Loss Point ◽  
Drought Avoidance

Deciduous dipterocarp forest (DDF) is the most extensive forest type in continental Southeast Asia, but across much of its range is functionally more similar to tropical savannas than tropical forests. We investigated water relations and drought responses of the four dominant tree species (two Shorea and two Dipterocarpus species) of the DDF in central Vietnam to determine how they responded to prolonged periods of drought stress. We quantified leaf water relations in nursery- and field-grown seedlings of the four species and conducted a dry-down experiment on 258 seedlings to study leaf water potential and morphological responses of the seedlings following the drought stress. The two Shorea and two Dipterocarpus species differed significantly in leaf water potential at turgor loss point and osmotic potential at full turgor, but they showed similar responses to drought stress. All species shed leaves and suffered from stem loss when exposed to water potentials lower than their turgor loss point (approximately −1.7 MPa for Dipterocarpus and −2.6 MPa for Shorea species). Upon rewatering, all species resprouted vigorously regardless of the degree of leaf or stem loss, resulting in only 2% whole-plant mortality rate. Our results suggest that none of the four deciduous dipterocarp species is drought tolerant in terms of their water relations; instead, they employ drought-adaptive strategies such as leaf shedding and vigorous resprouting. Given that all species showed similar drought avoidance and drought-adaptive strategies, it is unlikely that seasonal drought directly influences the patterns of species assembly in the DDF of Southeast Asia.

Osmotic Adjustment of Sorghum and Sunflower Crops in Response to Water Deficits and Its Influence on the Water Potential at Which Stomata Close

1978 ◽  
Vol 5 (5) ◽  
pp. 597 ◽  
Author(s):  
NC Turner ◽  
JE Begg ◽  
ML Tonnet
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Deficits ◽  
Rate Of Increase ◽  
Leaf Osmotic Potential ◽  
Response To Water

The soil and plant water status of irrigated and unirrigated sorghum [Sorghum bicolor (L.) Moench cv. TX610] and sunflower (Helianthus annuus L. cv. Hysun 30) crops were compared on several days from the late vegetative to the early grain-filling stages of development. Additionally, the stems of plants from the irrigated and unirrigated plots of both species were cut near their base; this caused the plants to quickly dry until the stomata closed. The leaf water potential and leaf osmotic potential were measured when the stomatal resistance reached 6 s cm-� to give the water potential for stomatal closure and to provide osmotic potentials at equal turgor. Carbohydrate and potassium levels of leaves were also monitored. The mean daily minimum leaf water potentials in the irrigated sorghum and sunflower did not decrease below - 1 7 MPa and - 2.0 MPa, respectively, but decreased to - 2.1 MPa in the unirrigated sorghum and -2.6 MPa in the unirrigated sunflower. The osmotic potential at stomatal closure in the rapidly dried plants decreased with increasing leaf water deficit in both sunflower and sorghum: in both species the osmotic potential decreased approximately 0.6 MPa for each megapascal decrease in leaf water potential. The results indicate that both sorghum and sunflower adjusted osmotically in response to water deficits and that adjustment occurred at a rate of at least 0.1 MPa per day. The lowering of osmotic potential persisted less than 9 days after the relief of stress in both sunflower and sorghum. The soluble sugar concentration increased linearly in both sunflower and sorghum with osmotic adjustment: the rate of increase of soluble sugars was significantly greater in sunflower than sorghum. No changes in potassium concentration were observed during osmotic adjustment. The water potential at which the stomata closed varied from - 1.5 to -2.6 MPa in sorghum and - 1.7 to -2.7 MPa in sunflower: the water potential that induced stomatal closure decreased as the osmotic potential decreased. Stomatal closure occurred at a mean turgor of -0-5 MPa in both species: systematic error in the measurement of osmotic potential on frozen and thawed leaf tissue is considered the reason for the low turgor potentials at stomatal closure. The adaxial stomatal closed before the abaxial stomata in the sorghum and unirrigated sunflower but, since the leaf water potential initially fell rapidly and then became stable before the adaxial stomata closed, both the adaxial and abaxial stomata closed at the same leaf water potential.

Comparing plant water relations for wheat with alternative pulse and oilseed crops grown in the semiarid Canadian prairie

2009 ◽  
Vol 89 (5) ◽  
pp. 823-835 ◽  
Author(s):  
H W Cutforth ◽  
S V Angadi ◽  
B G McConkey ◽  
M H Entz ◽  
D Ulrich ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Oilseed Crops ◽  
Pulse Crops ◽  
The Mean

Understanding the drought physiology of alternate crops is essential to assess the production risks of new cropping systems. We compared the water relations of dry (field) pea (Pisum sativum L.), chickpea (Cicer arietinum L.), canola (Brassica napus L.) and mustard (Brassica juncea L.) with spring wheat (Triticum aestivum L.) under different moisture availabilities in field trials conducted in 1997 and 1998 at Swift Current, SK. Stress experience and stress responses varied with crop type. In general, there were similarities in drought physiology between the two pulse crops and between the two oilseed crops. The mean predawn leaf water potential of pea was frequently lowest, while the mean midday leaf water potential of wheat was at least -0.40 MPa lower than for any other crop. The crops exhibited different strategies to overcome water stress. Wheat had the lowest osmotic potential at full turgor, except under drought when turgor was lowest for chickpea and wheat; the highest values were observed in Brassica spp. Mean midday pressure potentials were lowest in wheat (and mostly negative, indicating loss of turgor) and highest for the pulse crops. Mean midday pressure potential for canola was positive when well-watered, otherwise it was near 0. Despite lowering osmotic potential, wheat could not maintain positive turgor much of the time at midday. Pulse crops, with the contributions from both osmotic adjustment and cell elasticity, maintained positive turgor over a wider range of water potentials compared with the other crops. With regard to both osmotic adjustment and tissue elasticity, we ranked the crops from high to low ability to adjust to moderate to severe water stress as pulses > wheat > Brassica oilseeds. Key words: Leaf water, osmotic, turgor potentials, wheat, pulse, canola, semiarid prairie

Water stress and phenology in wheat

1977 ◽  
Vol 28 (2) ◽  
pp. 177 ◽  
Author(s):  
JF Angus ◽  
MW Moncur
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Mild Stress ◽  
Floral Initiation ◽  
Severe Stress ◽  
Development Models ◽  
Crop Development

Single wheat plants (cv. Gabo) were sown in tall pots and top-watered so that growth proceeded without stress until the time of floral initiation. Having reached this stage, plants encountered increasing stress as soil water was depleted. At intervals after the dawn leaf water potential, ψ1, had reached values of –5, –10, –15 bars etc., the stress was relieved with water sufficient for unstressed development until anthesis. The anthesis dates of plants which had encountered mild stress (ψ1 down to about ndash;15 bars) were ahead of the well-watered control, while those which had encountered more severe stress (ψ1 from about ndash;25 to ndash;40 bars) flowered after the controls. The results are discussed in relation to the possibilities of including the effects of stress in crop development models.

scholarly journals Changes in leaf water potential and photosynthesis of Bauhinia forficata Link under water deficit and after rehydration

Hoehnea ◽  
2013 ◽  
Vol 40 (1) ◽  
pp. 181-190 ◽  
Author(s):  
Rodrigo Fazani Esteves Sanches ◽  
Emerson Alves da Silva
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Strong Dependence ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Mean Values ◽  
Bauhinia Forficata ◽  
Response To Water

To evaluate the influence of different intensities of water deficit and rehydration on water relations and gas exchanges of Bauhinia forficata Link, plants were grown in a greenhouse for three months under the following water regimes: daily watered (control) and watered every 7 (7D) and 15 days (15D) returning to daily watering on 7D and 15D treatments at 75 days of the experiment. Aiming to evaluate short-term responses to re-hydration, plants of 7D and 15D treatments were re-watered 2 days before measurements and sampling was carried out at the 45th day of experiment. At fortnightly intervals (15, 30, 45, 60, 75, and 90 days) soil moisture (Usoil), leaf water potential (Ψwf), photosynthesis in response to photosynthetically active radiation (A × PPFD) to obtain the maximum net photosynthesis (Amax), and light saturation point (PARsat) were evaluated. The water deficit has affected water relations and photosynthesis with the lowest values observed in the treatments Usoil 7D, and 15D respectively, coinciding with the lowest Ψwf and Amax. Changes in PARsat in response to water deficit were observed showing mean values of 665, 275 and 254 µmol photons m-2 s-1 in control, 7D and 15D respectively. The return of daily watering after 75 days of experiment, promoted the recovery of Amax (7.8 and 9.6 µmol CO2 m-2 s-1) and PARsat (588 and 643 µmol photons m-2 s-1) in 7D and 15D respectively with values higher than control plants (4.7 µmol CO2 m-2 s-1 and 631 µmol photons m-2 s-1), suggesting a strong dependence of photosynthesis of Bauhinia forficata to the soil water availability.

Water stress conditioning of corn (Zea mays) in the field and the greenhouse

1985 ◽  
Vol 63 (4) ◽  
pp. 704-710 ◽  
Author(s):  
L. M. Dwyer ◽  
D. W. Stewart
Keyword(s):  
Zea Mays ◽  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Temperature Sensitive ◽  
Pressure Potential ◽  
Response To Water

Leaf water potential, osmotic potential, and leaf conductance were measured on corn (Zea mays L.) under water stress in the field and the greenhouse. Field-grown plants were subjected to several cycles of moderate water stress during vegetative growth, while greenhouse plants were well watered until just before the measurement period began following tasselling. In both the field and the greenhouse, leaf water potential declined at midday. Comparison of leaf water potential and osmotic potential measurements indicated that in both environments, the midday decline in leaf water potential was accompanied by a decline in osmotic potential. Since the decline in osmotic potential was greater than that accounted for by predicted volume changes resulting from normal daily dehydration, it was assumed to indicate osmotic adjustment. Despite these similarities, field-grown plants showed a greater response to water stress. Field plants underwent larger daily changes in leaf water potential and these were accompanied by larger changes in osmotic potential. As a result of this greater osmotic adjustment in the field, conductivity was higher at equivalent leaf water potentials and the critical leaf water potential was lower than in greenhouse-grown plants. In both environments, osmotic adjustment maintained leaf turgor (or pressure potential) in a narrow positive range. Although there was no direct relation between turgor potential and leaf conductivity, we hypothesize that the maintenance of a positive turgor potential during daylight hours is significant for growth since it may allow the moisture- and temperature-sensitive process of leaf expansion to proceed during the warmer daylight hours, even under moderate water stress.

scholarly journals Wine Grape Response to Foliar Particle Film under Differing Levels of Preveraison Water Stress

HortScience ◽  
2008 ◽  
Vol 43 (5) ◽  
pp. 1392-1397 ◽  
Author(s):  
Krista Shellie ◽  
D. Michael Glenn
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Leaf Gas Exchange ◽  
Leaf Water ◽  
Soluble Solids ◽  
Wine Grape ◽  
Solids Concentration ◽  
Soluble Solids Concentration

We investigated how foliar application of kaolin particle film influenced diurnal leaf gas exchange, leaf water potential, yield, and berry maturity of a red (‘Merlot’) and white (‘Viognier’) wine grape (Vitis vinifera L.) cultivar under differing levels of water stress over two growing seasons (2005 and 2006) in the warm, semiarid climate of southwestern Idaho. Net diurnal stomatal conductance (g S) was increased by particle film and the effect varied according to vine water status. Particle film delayed the onset of diurnal decline in g S under mild water stress (leaf water potential ≈ –1.2 MPa) but had no influence on leaf gas exchange when vines were under greater water stress (leaf water potential ≈ –1.4 MPa). Correlation between soluble solids concentration and titratable acidity (‘Viognier’) and between berry fresh weight and yield (‘Merlot’) was higher with than without particle film, suggesting that particle film may attenuate the influence of other factors affecting expression of these traits. Particle film was associated with an increase in berry weight in ‘Merlot’ and with an increase in berry soluble solids concentration in ‘Viognier’, suggesting that the film may increase vine-carrying capacity. Midday leaf water potential throughout the growing season was not influenced by particle film. Fruit surface browning was observed on deficit-irrigated, particle film-treated vines on exposed clusters on the west side of the canopy, indicating that the film did not eliminate development of heat stress symptoms on fruit under the most extreme environmental conditions evaluated in this study.

scholarly journals Interactions between leaf water potential, stomatal conductance and abscisic acid content of orange trees submitted to drought stress

2004 ◽  
Vol 16 (3) ◽  
pp. 155-161 ◽  
Author(s):  
Mara de Menezes de Assis Gomes ◽  
Ana Maria Magalhães Andrade Lagôa ◽  
Camilo Lázaro Medina ◽  
Eduardo Caruso Machado ◽  
Marcos Antônio Machado
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Acid Content ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Orange Trees ◽  
Abscisic Acid Content

Thirty-month-old 'Pêra' orange trees grafted on 'Rangpur' lemon trees grown in 100 L pots were submitted to water stress by the suspension of irrigation. CO2 assimilation (A), transpiration (E) and stomatal conductance (g s) values declined from the seventh day of stress, although the leaf water potential at 6:00 a.m. (psipd) and at 2:00 p.m. (psi2) began to decline from the fifth day of water deficiency. The CO2 intercellular concentration (Ci) of water-stressed plants increased from the seventh day, reaching a maximum concentration on the day of most severe stress. The carboxylation efficiency, as revealed by the ratio A/Ci was low on this day and did not show the same values of non-stressed plants even after ten days of rewatering. After five days of rewatering only psi pd and psi2 were similar to control plants while A, E and g s were still different. When psi2 decreases, there was a trend for increasing abscisic acid (ABA) concentration in the leaves. Similarly, stomatal conductance was found to decrease as a function of decreasing psi2. ABA accumulation and stomatal closure occurred when psi2 was lower than -1.0 MPa. Water stress in 'Pera´ orange trees increased abscisic acid content with consequent stomatal closure and decreased psi2 values.

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