Seasonal trends of several water relation parameters in Cryptomeriajaponica seedlings

1986 ◽  
Vol 16 (1) ◽  
pp. 74-77 ◽  
Author(s):  
Kyoji Doi ◽  
Yasushi Morikawa ◽  
Thomas M. Hinckley
Keyword(s):  
Water Relations ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Dry Weight ◽  
Water Relation ◽  
Evaporative Demand ◽  
Seasonal Trends ◽  
Air Temperatures ◽  
Turgor Maintenance

The role of osmotic adjustment in turgor maintenance during periods of either cold soil or plant temperatures or of high evaporative demand was described for 2-year-old Cryptomeriajaponica D. Don seedlings. Water relations parameters were measured by the pressure–volume technique for a 1-year period. The osmotic potential at full turgidity and at the point of zero turgor ranged from −1.32 to −2.70 MPa and from −1.70 to −3.52 MPa, respectively. Highest values of osmotic potential were associated with the period of foliage expansion, while lowest values were noted in mid-February during the period of lowest air temperatures. The role of solute changes or changes in symplastic water relative to tissue dry weight in osmotic adjustment is described.

Osmotic Adjustment, Induced by Drought, in Seedlings of Three Eucalyptus Species

1986 ◽  
Vol 13 (5) ◽  
pp. 597 ◽  
Author(s):  
BA Myers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Dry Weight ◽  
Eucalyptus Species ◽  
Plant Water ◽  
Mature Trees ◽  
Mean Values ◽  
Turgor Maintenance ◽  
Plant Water Potential

Osmotic adjustment was observed in pot-grown seedlings of Eucalyptus behriana, E. microcarpa and E. polyanthemos that had been subjected to one and two periods of drought. The osmotic potential of sap expressed from rehydrated leaves was significantly lower in seedlings which had wilted twice (-2.02 � 0.05 MPa) compared with those which had wilted once (-1.86 � 0.05 MPa) and those which had been watered daily (-1.66 � 0.05 MPa). After two drought cycles, seedlings began to wilt at lower mean values of plant water potential (- 3.51 � 0.22 MPa) than those which had not wilted previously (-3.14 � 0.22 MPa). Thus drought-induced osmotic adjustment apparently enhanced turgor maintenance. The ratio of turgid weight to dry weight was slightly, but significantly, smaller in the seedlings subjected to two drought cycles (3.83 � 0.04 MPa) compared with those subjected to one drought cycle (4.05 � 0.04). The osmotic adjustment that was induced by two drought cycles in these seedlings was about one third of the observed seasonal osmotic adjustment in mature trees of E. behriana and E. microcarpa in the field.

Changes in shoot water relations parameters of yellow-cedar (Chamaecyparis nootkatensis) in response to environmental conditions

1996 ◽  
Vol 74 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Steven C. Grossnickle ◽  
John H. Russell
Keyword(s):  
Water Relations ◽  
Environmental Conditions ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Late Summer ◽  
Water Relation ◽  
Elastic Component ◽  
Root Temperature ◽  
Turgor Loss Point ◽  
Chamaecyparis Nootkatensis

Yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) shoot water relations parameters were measured in response to (i) seasonal changes in photoperiod and temperature and (ii) controlled changes in root temperature and soil moisture. Pressure–volume curves determined measurements of shoot water relation parameters. Osmotic potential at saturation (Ψsat) and turgor loss point (Ψtlp) were lowest during February at −1.73 and −2.35 MPa, respectively. Both Ψsat and Ψtlp increased in the spring to a high in July of −1.05 and −1.28 MPa, respectively, when shoot growth was occurring. Total turgor (ΨPTotal) was 18.2 MPa in December and declined to its lowest level of 5.98 MPa in July. Increased ΨPTotal from late summer through winter could be attributed to osmotic and (or) elastic components, while decreased ΨPTotal in the spring was due to a decrease in both osmotic and elastic components. Both Ψsat and Ψtlp decreased as root temperatures were reduced from 22 to 1 °C. There was an increase in ΨPTotal as root temperatures declined from 15 to 8 °C because of both osmotic and elastic adjustment, with osmotic adjustment the primary factor. Turgor decreased at root temperatures below 8 °C, even though osmotic adjustment was occurring, and this was due to a reduction in the elastic component. Both Ψsat and Ψtlp decreased in response to drought, though Ψtlp decreased at a greater rate. Increased turgor during the initial stages of long-term drought results from an increase in both osmotic and elastic components, while increased turgor was solely due to the osmotic component as drought became more severe. Under rapid drought, turgor adjustment was minimal because the increased osmotic component was offset by a decrease in the elastic component. Results from these experiments indicate that turgor maintenance of yellow-cedar occurs through the use of both osmotic and elastic components in varying degrees at different times of the year and under differing environmental conditions. Keywords: Chamaecyparis nootkatensis, osmotic potential at saturation and turgor loss point, total turgor with osmotic and elastic components, seasonal patterns, root temperature, drought.

Shoot phenology and water relations of Piceaglauca

1989 ◽  
Vol 19 (10) ◽  
pp. 1287-1290 ◽  
Author(s):  
Steven C. Grossnickle
Keyword(s):  
Osmotic Potential ◽  
Dry Weight ◽  
Shoot Elongation ◽  
Water Relation ◽  
Day Length ◽  
Late Winter ◽  
Turgor Loss Point ◽  
Shoot Dry Weight ◽  
Length Changes ◽  
Shoot Phenology

Piceaglauca var. albertiana (S. Brown) Sarg. shoot phenology and water relation parameters were monitored monthly for 1 year. Seedlings were kept outdoors, well watered, and exposed to seasonal changes in temperature and day length. Changes in shoot water relation parameters corresponded with changes in phenology. During spring, shoot elongation, osmotic potential at saturation, and turgor loss point were least negative, −1.30 and −1.56 MPa, respectively, whereas bulk modulus of elasticity at full turgor was at its highest, 22 MPa. Both osmotic potential at saturation and turgor loss point were most negative, −2.01 and −2.73 MPa, respectively, during late winter just before bud break. Shoot dry weight fraction was at its lowest, 0.33 g dry wt./g shoot weight and maximum symplastic water per unit weight of shoot tissue was at its highest, 3.99 g H2O/g dry wt., during spring shoot elongation. Number of osmoles of solute per kilogram shoot dry weight was highest during spring and late summer shoot elongation phases, 1.03 and 0.91 osmol/kg dry wt., respectively. These data suggest that P. glauca seedlings do not adjust well to dry site conditions.

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

scholarly journals The Role of Carbohydrates in Active Osmotic Adjustment in Apple under Water Stress

1992 ◽  
Vol 117 (5) ◽  
pp. 816-823 ◽  
Author(s):  
Zhongchun Wang ◽  
Gary W. Stutte
Keyword(s):  
Water Stress ◽  
Malus Domestica ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Soluble Sugars ◽  
Sugar Alcohol ◽  
Apple Trees ◽  
Mature Leaves ◽  
Leaf Osmotic Potential

Greenhouse grown 2-year-old potted `Jonathan' apple trees (Malus domestica Borkh.) were subjected to various levels of water stress in February. Midday leaf water potential (ψW), leaf osmotic potential (ψS), soluble sugars, and starch contents of mature leaves were measured throughout the development of water stress to determine whether active osmotic adjustment could be detected and whether carbohydrates were involved. Active adjustments of 0.6 MPa were observed 3 and 5 days, respectively, after water stress was initiated. Leaf turgor potential (ψP) could not be maintained through the osmotic adjustment when ψW dropped below -1.6 MPa. Sorbitol, glucose, and fructose concentrations increased while sucrose and starch levels decreased significantly as water stress developed, strongly suggesting that sugar alcohol and monosaccharide are the most important osmotica for adjustment. Sorbitol was a primary carbohydrate in the cell sap and accounted for > 50% of total osmotic adjustment. The partitioning of newly fixed W-labeled photosynthates in mature leaves was not affected by water stress immediately after the 30-min 14CO2 treatment. All the W-labeled carbohydrates decreased in the labeled leaves very rapidly after 14CO2 labeling. The decrease in 14C-sorbitol was greater than the decrease in other carbohydrates under both well-watered and stressed conditions. After 24 hours of water stress, however, the percentage of 14C-sorbitol increased while the percentages of sucrose, starch, glucose, and fructose decreased significantly with increasing levels of stress. The ratio of 14C-sorbitol in leaves with ψW = -3.5 MPa to leaves with ψW = -0.5 MPa was significantly higher than that of 14C-sucrose, 14C-glucose, W-fructose, or 14C-starch.

scholarly journals 405 Glycinebetaine Accumulation in Red Beet under Salinity

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 513E-513
Author(s):  
Guntur V. Subbarao ◽  
Raymond M. Wheeler ◽  
L.H. Levine ◽  
Gary W. Stutte
Keyword(s):  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Dry Weight ◽  
Hydroponic System ◽  
Red Beet ◽  
Leaf Osmotic Potential ◽  
Sodium Toxicity ◽  
Relative Water ◽  
The Mean ◽  
External Salinity

Accumulation of glycinebetaine occurs in Chenopodiaceae members and is thought to assist in osmotic adjustment and protect cytoplasm from sodium toxicity. Red beet has an ability to tolerate high tissue sodium levels, which may result in increased glycinebetaine production. To test this hypothesis, two cultivars of red beet ['Scarlet Supreme' (SS) and `Ruby Queen' (RQ)] were grown under nonsaline (4.75 mM Na) and saline (54.75 mM Na) conditions in a recirculating hydroponic system for 42 days at elevated CO2 (1200 μmol•mol-1) in a growth chamber. Leaf glycinebetaine level, relative water content, and osmotic potential were measured at weekly intervals. Leaf glycinebetaine levels increased with plant age and reached a maximum of 67 μmol•g-1 dw under nonsaline and 101 μmol•g-1 dry weight (dw) under saline conditions at 42 days in SS; in RQ, the glycinebetaine levels reached a maximum of 91 μmol•g-1 dw under nonsaline and 121 μmol•g-1 dw under saline conditions by 26 days. The mean glycinebetaine levels were increased over two-thirds under saline conditions in both the cultivars. RQ accumulated significantly higher (37% more under nonsaline, and 46% more under salinity) glycinebetaine than SS. The turgid leaf osmotic potential of RQ was consistently higher than SS under nonsaline (2.23 MPa in RQ vs. 1.82 MPa in SS) and saline (2.48 MPa in RQ vs. 2.02 MPa in SS) conditions. The results indicate that higher glycinebetaine levels in the leaf could result in better osmotic adjustment, and glycinebetaine accumulation in red beet can vary among cultivars and is strongly affected by external salinity.

Leaf and root osmotic adjustment in drought-stressed Quercusalba, Q. macrocarpa, and Q. stellata seedlings

1988 ◽  
Vol 18 (1) ◽  
pp. 1-5 ◽  
Author(s):  
William C. Parker ◽  
Stephen G. Pallardy
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Root Tissue ◽  
Tissue Elasticity ◽  
Tissue Water ◽  
Before And After ◽  
Relative Water

The leaf and root tissue water relations of Quercusalba L., Quercusmacrocarpa Michx., and Quercusstellata Wang. seedlings before and after drought were examined to evaluate the occurrence and comparative extent of osmotic adjustment in seedlings of these species. Drought resulted in active osmotic adjustment in leaves of all three species, with decreases in osmotic potential at full tissue hydration and at the turgor loss point from 0.25 to 0.60 MPa. Active osmotic adjustment in Q. stellata, and increased root tissue elasticity in Q. macrocarpa and Q. alba, resulted in turgor loss of roots occurring at a water potential 0.36 to 0.66 MPa lower in drought-stressed than in well-watered seedlings. Species differed in tissue water relations only before drought, with Q. stellata exhibiting lower osmotic potentials than Q. alba and Q. macrocarpa. Estimates of the osmotic potential at full saturation were generally lower in leaves than in roots, but the osmotic potential at turgor loss was similar. Roots exhibited turgor loss at lower values of relative water content and experienced a more gradual decrease in water potential per unit water content during dehydration than did leaves. This response indicates greater relative tissue capacitance in roots than in leaves in these species.

Osmotic Adjustment in Water Stressed Grapevine Leaves in Relation to Carbon Assimilation

1993 ◽  
Vol 20 (3) ◽  
pp. 309 ◽  
Author(s):  
ML Rodrigues ◽  
MM Chaves ◽  
R Wendler ◽  
MM David ◽  
WP Quick ◽  
...  
Keyword(s):  
Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Soluble Sugars ◽  
Carbon Assimilation ◽  
Dry Weight ◽  
Leaf Water ◽  
Soluble Carbohydrates ◽  
Water Fraction ◽  
The Difference

The response of grapevine plants to severe water deficit (predawn leaf water potential of - 1.13 MPa), imposed at a rate of about 0.16 MPa day-1 was studied in terms of leaf water relations characteristics, stomatal behaviour and gas exchange. Carbohydrate status of leaves was also analysed in order to assess the contribution of soluble sugars as osmotic solutes during drought. Pressure/volume analysis showed an active osmotic adjustment in water-stressed leaves, which decreased osmotic potential at full turgor by 0.45 MPa and the apoplastic water fraction showed a reduction of 19% as compared to the well- watered plants. Cell wall elasticity was not significantly affected by water stress, and turgor loss point in stressed leaves was reached at lower water potential and relative water content values than in the well-watered controls. Photosynthesis was markedly reduced in water-stressed plants. However, well-watered and water-stressed leaves had similar concentrations of glucose and fructose. The concentrations of sucrose and starch decreased in water-stressed leaves. This accounted for a marked decrease in the ratio of leaf dry weight to area in droughted plants. The changes in concentrations of soluble carbohydrates could not account for the difference in osmotic potential between water-stressed and well-watered leaves.

Evaluation of the differential osmotic adjustments between roots and leaves of maize seedlings with single or combined NPK-nutrient supply

2007 ◽  
Vol 34 (3) ◽  
pp. 228 ◽  
Author(s):  
Christoph Studer ◽  
Yuncai Hu ◽  
Urs Schmidhalter
Keyword(s):  
Drought Stress ◽  
Plant Growth ◽  
Root Growth ◽  
Osmotic Adjustment ◽  
Turgor Pressure ◽  
Nutrient Supply ◽  
Interactive Effects ◽  
Maize Seedlings ◽  
Turgor Maintenance

Many physiological mechanisms associated with nutrient supply have been implicated as improving plant growth under drought conditions. However, benefits to plant growth under drought might derive from an increased recovery of soil water through osmotic adjustment in the shoots and especially in the roots. Thus, experiments were carried out to investigate the effects of the nutrients N, P and K applied singly or in combination, on the osmotic adjustment and turgor maintenance in the roots and leaves of maize seedlings. The seedlings were harvested between 18 and 37 days after sowing according to the soil matric threshold potentials. Soil matric potentials and shoot and root biomass were determined at harvest. Turgor pressure and osmotic adjustment of the leaves and roots were estimated by measurements of their water and osmotic potentials. Results showed that plants with either of the combined fertilisation treatments NPK or NP grew faster at a given level of drought stress than those with no fertilisation, N, P or K applied individually or the combined nutrient treatments PK and NK. Among the fertiliser applications with either a single or two combined nutrients, plants treated with any of N, P or NP grew faster than those with either K or NK. The association between the interactive effects of nutrients and drought stress on the osmotic adjustment and turgor maintenance in roots may partially explain the role of nutrients in drought tolerance of maize seedlings. In particular, the roots exhibited a higher osmotic adjustment than the leaves for all nutrient treatments, suggesting that shoot growth shows a higher sensitivity to water deficit compared to root growth. We conclude that the maintained turgor of roots under drought stress obtained with an optimal nutrient supply results in better root growth and apparently promotes overall plant growth, suggesting that osmotic adjustment is an adaptation not only for surviving stress, but also for growth under such conditions.

scholarly journals Role of Gibberellin A4 and Gibberellin Biosynthesis Inhibitors on Flowering and Stem Elongation in Petunia under Modified Light Environments

HortScience ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 134-137 ◽  
Author(s):  
T.A. Cerny-Koenig ◽  
J.E. Faust ◽  
N.C. Rajapakse
Keyword(s):  
Stem Elongation ◽  
Dry Weight ◽  
Gibberellin Biosynthesis ◽  
Shoot Dry Weight ◽  
Long Day ◽  
Air Temperatures ◽  
Biosynthesis Inhibitors ◽  
Growing Environment ◽  
Ga Biosynthesis

In our previous experiments, greenhouse films that selectively remove far-red (FR) light from the growing environment reduced the stem elongation but delayed anthesis of long day plants. In the present research we investigated if the application of gibberellin A4 and gibberellin (GA) biosynthesis inhibitors could overcome the delay in anthesis of petunia (Petunia ×hybrida Vilm.-Andr.), a quantitative long-day plant, under a FR light deficient environment. The GA biosynthesis inhibitors prohexadione-Ca and exo-C-16,17-dihydro GA5 (GA5) were used because of their ability to prevent catabolism of active GAs. Anthesis and stem elongation were investigated under control, red (R; 600 to 700 nm) and FR (700 to 800 nm) light-absorbing (AR and AFR) films. The R:FR ratios of control, AR, and AFR films were 1.03, 0.71, and 1.51, respectively. Air temperatures among treatment chambers were not different. AR film did not affect anthesis or stem elongation, but AFR film reduced stem elongation and delayed anthesis by 12 days. Exogenous application of GA5 had no effect on stem elongation, shoot dry weight or days to anthesis at any concentration (0 to 100 mg·L-1) tested under control, AR, or AFR films. Anthesis was delayed with increasing concentration (0 to 200 mg·L-1) of prohexadione-Ca under all treatments. Prohexadione-Ca at 200 mg·L-1 delayed anthesis by 11 and 7 days under the control and AFR film, respectively, suggesting an interaction between light quality and prohexadione-Ca treatment. Exogenous GA4 accelerated anthesis under both films but the promotion was greater under the AFR films. However, GA4 treatment increased stem elongation and the increase in stem elongation was greater under the AFR film. Addition of GA5 to GA4 had no added effect on flowering and failed to reduce stem elongation. Therefore, GA or GA inhibitors are not suitable for flower promotion under AFR films.

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