The effect of humidity, root excision, and potassium supply on hypocotyl elongation in dark-grown seedlings of Helianthus annuus

1984 ◽  
Vol 62 (3) ◽  
pp. 420-428 ◽  
Author(s):  
Gordon I. McIntyre ◽  
John S. Boyer
Keyword(s):  
Helianthus Annuus ◽  
Osmotic Potential ◽  
Stem Elongation ◽  
Growth Responses ◽  
Pressure Potential ◽  
Cell Turgor ◽  
Low Humidity ◽  
Potassium Supply ◽  
Root Excision ◽  
Growing Region

When seedlings of Helianthus annuus L. were grown in the dark with their roots in vermiculite saturated with distilled water the rate of elongation of the hypocotyl was significantly increased by increasing the relative humidity around the shoot from approximately 25 to 100%. This response was correlated with a reduction in transpiration rate of approximately 95% and with increases in the water potential and cell turgor in the growing region. Measurements with a transducer revealed very rapid growth responses to changes in humidity, usually preceded by a variable period of growth oscillations. Excision of the roots, either in water or in air, induced an immediate increase in rate of elongation at low humidity, but at high humidity this response was delayed and markedly reduced. The growth rate was significantly increased by supplying 10 mM KCl to the roots at both high and low humidity. The response to K was slower than the response to humidity and was correlated with a significant reduction in the osmotic potential of the growing region. A growth response was first detected approximately 45 min after the application of K to the roots and 10 min after application to the shoot. These results arc consistent with the hypothesis that, in the intact plant, stem elongation is largely controlled by the interacting effects on cell turgor of transpiration-induced negative pressure potential in the apoplast and the osmotic potential of the growing cells.

Response of red-osier dogwood (Cornus sericea) seedlings to NaCl during the onset of bud break

2006 ◽  
Vol 84 (5) ◽  
pp. 844-851 ◽  
Author(s):  
Jennifer Mustard ◽  
Sylvie Renault
Keyword(s):  
Cell Wall ◽  
Osmotic Potential ◽  
Dry Mass ◽  
Bud Break ◽  
Pressure Potential ◽  
Shoot Height ◽  
Cell Wall Elasticity ◽  
Greenhouse Study ◽  
Cornus Sericea ◽  
Bud Breaking

A greenhouse study was designed to test the response of red-osier dogwood (Cornus sericea L.) to NaCl during the onset of bud break. Seedlings treated with 50 mmol·L–1 NaCl for 32 d had lower shoot dry mass and shoot height than untreated seedlings. Transpiration and photosynthetic rates, chlorophyll b and carotenoid concentrations of red-osier dogwood seedlings were significantly reduced by NaCl treatment. The shoots of seedlings treated with 50 mmol·L–1 NaCl had a higher bulk modulus of cell wall elasticity than those of untreated seedlings, but the water potential components determined from the pressure-volume curves, osmotic potential and pressure potential at full turgor and osmotic potential at pressure loss, suggest that this change did not contribute to salt tolerance. Minor changes, including a small increase in arabinose of the hemicellulose fraction and a decrease in both galactose and rhamnose of the pectin fraction, also occurred in response to NaCl treatment. These changes in cell wall composition and elasticity could be partly attributed to differences in the developmental stage of the shoot tissues resulting from the delay in bud breaking in salt treated plants.

Light regulation of endogenous salicylic acid levels in hypocotyls of Helianthus annuus seedlings

Botany ◽  
2010 ◽  
Vol 88 (7) ◽  
pp. 668-674 ◽  
Author(s):  
Leonid V. Kurepin ◽  
Linda J. Walton ◽  
David M. Reid ◽  
C. C. Chinnappa
Keyword(s):  
Salicylic Acid ◽  
Helianthus Annuus ◽  
Leaf Growth ◽  
Stem Elongation ◽  
Light Regulation ◽  
Shade Avoidance ◽  
Light Conditions ◽  
Direct Role ◽  
Positive Effects

Plants growing in canopy shade typically exhibit increased stem elongation and reduced leaf growth. This is as a result of direct interactions between plant photoreceptors sensing the change (reduction) in the ratio of red to far-red (R/FR) light and photosynthetically active radiation (PAR) and plant hormones, and regulating these morphological traits. The effect of the varying light conditions found in shade on endogenous salicylic acid (SA) content was tested, and the possible role of SA in shade avoidance by sunflower ( Helianthus annuus L.) hypocotyls was examined. A logarithmic increase in PAR irradiance levels increased endogenous SA levels roughly 10-fold. Separation of individual light wavelengths (R, FR, and blue) constituting the PAR irradiance of sunlight, established that only FR light had significant and positive effects on endogenous SA levels. Further, a low R/FR ratio significantly increased the endogenous SA content in hypocotyls compared with normal and high R/FR ratios. Uncoupling the effect of R/FR ratio and PAR irradiance on endogenous SA content demonstrated that PAR irradiance is a much stronger signal than FR light-enrichment. Thus, while a low R/FR ratio increases the SA content in sunflower hypocotyls, low PAR, the other component of canopy shade, decreases the SA content much more effectively than low R/FR ratio increases it. Therefore, it appears that SA probably has no direct role in shade avoidance effects.

scholarly journals Effects of different concentration of Ca (NO 3)2 on quinoa treated with salinity

2016 ◽  
Author(s):  
Hong Yan ◽  
Fulai Liu
Keyword(s):  
Cell Division ◽  
Osmotic Potential ◽  
Stomatal Density ◽  
Turgor Pressure ◽  
Calcium Nitrate ◽  
Chenopodium Quinoa ◽  
Average Diameter ◽  
Root Apical Meristem ◽  
Root Characteristics ◽  
Cell Turgor

Salinity has some adverse effects on the morphology and physiology in many crops. To alleviate the damages of salinity, the applications of calcium nitrate on quinoa-treated NaCl (Chenopodium quinoa Willd) were investigated under the supported-hydroponic environment. The plants were exposed to 200mM NaCl with 20mM and 150mM Ca (NO 3 ) 2 (EC 18.61~37.85 ds·m -1 and osmotic potential -0.89~-1.71MPa), and sampled for measurements of osmotic potential, stomatal characteristics, and root characteristics. The presence of 200 mM NaCl alone decreased the relative parameters in different degrees. In all treatments, the indexes on stomatal characteristic were decreased with increasing electrical conductivity (EC) levels except for stomatal density. Stomatal conductance decreased more markedly when osmotic potential reached -0.89Mpa. Increasing in stomatal density observed in higher Ca(NO 3 ) 2 level (150mM) might be caused by the inhibition of cell division in the epidermis , which was also due to reduction of osmotic potential of the solutions.A similar trend was observed for osmotic potentials in the same tissue, which were deceased with increasing EC of the solutions. Although no significant differences in the all treatments were observed for the average diameter of roots, the beneficial effect of Ca(NO 3 ) 2 application at the concentration of 20 mM was significant in projected area, surface area, and volume. The phenomenon showed that moderate reduction in osmotic potential was favorable to cell extension due to maintaining cell turgor pressure. Much lower osmotic potential possibly inhibited cell division of root apical meristem. From the above results, it might be concluded that the effects of Ca(NO 3 ) 2 applications depended on the concentration, while the significant differences between the stomata and root morphology represented the tissue-specific as well.

Turgor and cell wall yielding in dicot leaf growth in response to changes in relative humidity

2000 ◽  
Vol 27 (12) ◽  
pp. 1131 ◽  
Author(s):  
Marcelo D. Serpe ◽  
Mark A. Matthews
Keyword(s):  
Growth Rate ◽  
Leaf Growth ◽  
Air Humidity ◽  
Steady Growth ◽  
Control Growth ◽  
Steady Rate ◽  
Cell Turgor ◽  
Low Humidity ◽  
Variable Wall ◽  
Marked Dependence

Epidermal cell turgor (P) and leaf growth in Begonia argenteo-guttata L. were monitored simultaneously following changes in air humidity in order to evaluate P–growth relations. A decrease in air humidity from 70 to 5% caused a decrease in P of 0.05 MPa. This small decrease in P resulted in cessation of growth. Subsequently, growth recovered partially at constant P, indicating an increase in wall yielding to P. Notwithstanding this increase in wall yielding, the steady growth rates showed a marked dependence on P. Decreases in P of 0.05 MPa caused a 30–40% reduction in the steady rate of elongation. These results were reversible. Upon a step increase in air humidity from 5 to 70%, P and growth rate rapidly increased. Subsequently, growth declined without a corresponding decrease in P, although the rate of growth remained higher than at low humidity. The partial self-stabilization of growth following P changes and the positive relationship between steady growth rate and P are consistent with the notion that wall yielding is controlled by interactions between P and metabolism. Results are discussed in relation to biophysical factors that control growth and to present theories that accommodate variable wall yielding.

Stem and leaf growth of alpine sun and prairie shade ecotypes of Stellaria longipes under different photoperiods: role of ethylene

2006 ◽  
Vol 84 (9) ◽  
pp. 1496-1502 ◽  
Author(s):  
Linda J. Walton ◽  
Leonid V. Kurepin ◽  
David M. Reid ◽  
C.C. Chinnappa
Keyword(s):  
Leaf Growth ◽  
Stem Elongation ◽  
Leaf Length ◽  
Leaf Expansion ◽  
Alpine Plants ◽  
Growth Responses ◽  
Stellaria Longipes ◽  
Length And Area ◽  
Radiation Conditions

Plant ecotypes of Stellaria longipes Goldie from competitive, shade-adapted prairie habitat and less competitive, nonshaded alpine habitat were subjected to shortened or extended photoperiod conditions. Increasing daylength was positively correlated to increased stem elongation in both ecotypes. Leaf length and area for shade (prairie) plants was significantly altered with increased photoperiods, whereas sun (alpine) plants exhibited minimal leaf expansion in response to increased photoperiod. Increased ethylene evolution in the alpine genotype during rapid stem elongation and extended photoperiods suggests that ethylene plays a growth regulatory role in this sun-adapted genotype. The prairie genotype evolved less ethylene during these same periods, indicating either a diminished requirement for elevated ethylene to effect elongation and leaf expansion responses or possibly increased ethylene sensitivity because of interactions with other hormones, such as gibberellin or auxin. The sun genotype consistently produced more ethylene than the shade genotype under all photoperiod treatments. We conclude that photoperiod alters stem elongation and leaf expansion responses; similar trends were observed for extended photoperiods as were observed for shaded conditions, specifically low light intensity (photosynthetically active radiation) conditions. Further, ethylene levels altered during these responses, especially in sun-adapted alpine plants, which suggests that ethylene is involved in these growth responses.

scholarly journals Drainage and Stand Growth Response in Peatland Forests—Description, Testing, and Application of Mechanistic Peatland Simulator SUSI

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 293
Author(s):  
Ari Laurén ◽  
Marjo Palviainen ◽  
Samuli Launiainen ◽  
Kersti Leppä ◽  
Leena Stenberg ◽  
...  
Keyword(s):  
Growth Response ◽  
Model Development ◽  
Cost Benefit ◽  
Weather Conditions ◽  
Growth Responses ◽  
Growth Data ◽  
Low Oxygen ◽  
Stand Growth ◽  
Network Maintenance ◽  
Potassium Supply

Drainage is an essential prerequisite in peatland forest management, which generally, but not always, increases stand growth. Growth response depends on weather conditions, stand and site characteristics, management and biogeochemical processes. We constructed a SUSI-simulator (SUoSImulaattori, in Finnish), which describes hydrology, stand growth and nutrient availability under different management, site types and weather conditions. In the model development and sensitivity analysis, we used water table (WT) and stand growth data from 11 Scots pine stands. The simulator was validated against a larger dataset collected from boreal drained peatlands in Finland. In validation, SUSI was shown to predict WT and stand growth well. Stand growth was mainly limited by inadequate potassium supply, and in Sphagnum peats by low oxygen availability. Model application was demonstrated for ditch network maintenance (DNM) by comparing stand growth with shallow (−0.3 m) and deep ditches (−0.9 m): The growth responses varied between 0.5 and 3.5 m3 ha−1 in five years, which is comparable to experimental results. SUSI can promote sustainable peatland management and help in avoiding unnecessary drainage operations and associated environmental effects, such as increased carbon emissions, peat subsidence, and nutrient leaching. The source code is publicly available, and the modular structure allows model extension to cost–benefit analyses and nutrient export to water courses.

scholarly journals Water Relation Parameters of the Cortex Tissue of Fresh ‘Fuji’ Apple Fruit Determined by Centrifugation

HortScience ◽  
2011 ◽  
Vol 46 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Xue-Min Hou ◽  
Zi-Hua Wang ◽  
Xi-Min Deng ◽  
Guo-Hui Li
Keyword(s):  
Elastic Modulus ◽  
Osmotic Potential ◽  
Water Relation ◽  
Apple Fruit ◽  
Pressure Potential ◽  
Centrifuge Method ◽  
Turgor Loss Point ◽  
Relative Water ◽  
Fuji Apple ◽  
Bulk Elastic Modulus

This experiment was carried out to obtain a pressure–volume (P-V) curve and Höfler diagram of the cortex tissue of fresh ‘Fuji’ apple fruit (Malus ×domestica Borkh.) with a novel centrifuge method. Based on the P-V curve and Höfler diagram, several water relation parameters of cortex tissue were determined and the interrelationship of these parameters was established. Turgor loss point (TLP) occurred at –1.74 MPa and 73.7% of relative water content (R*). At full hydration, osmotic potential (ψS) was –1.30 MPa and symplastic water accounted for 86.8% of R*. Bulk elastic modulus decreased linearly by 28% as pressure potential declined from 1.30 MPa at full hydration to zero at the TLP. This centrifuge technique can provide a simple and efficient way to determine water relation parameters of fleshy fruits.

Physiological responses of three northern conifers to rapid and slow induction of moisture stress

1985 ◽  
Vol 63 (7) ◽  
pp. 1171-1176 ◽  
Author(s):  
G. F. Buxton ◽  
D. R. Cyr ◽  
E. B. Dumbroff ◽  
D. P. Webb
Keyword(s):  
Polyethylene Glycol ◽  
Osmotic Potential ◽  
White Spruce ◽  
Moisture Stress ◽  
Jack Pine ◽  
Soil Drying ◽  
Mild Stress ◽  
Pressure Potential ◽  
Polyethylene Glycol 400 ◽  
Drought Period

The response of black and white spruce and jack pine to slow and rapid induction of moisture stress was evaluated during soil drying and exposure to liquid cultures containing polyethylene glycol 8000. Marked changes in water, osmotic, and pressure potentials were observed in all three species, but water potentials were the most sensitive indicators of moisture stress. Osmotic potentials were sensitive to mild stress in polyethylene glycol (−400 kPa), but they held relatively steady at higher stress intensities (−800 to −1600 kPa). Large decreases in osmotic potential were recorded in white spruce and jack pine during severe drying stress late in the drought period and these changes were accompanied by large decrements in water and pressure potentials. Significant changes in osmotic potential were not observed in black spruce prior to seedling death. Losses in pressure potential were only observed at −1600 kPa of polyethylene glycol stress, although wilting in young tissue was apparent at lower stress intensities. Pressure potentials of plants in the soil-drying test fell well below those recorded in the polyethylene glycol study. The highest resistance to loss of turgor and the maximum adjustment to moisture stress were observed in white spruce. Shoot growth and transpiration declined in the three conifers at relatively low stress intensities. Total chlorophyll and the chlorophyll stability index decreased during drought, but the differences recorded among species were not clearly related to observed differences in drought tolerance. Cation concentrations did not change during stress.

scholarly journals Wild and Cultivated Sunflower (Helianthus annuus L.) Do Not Differ in Salinity Tolerance When Taking Vigor into Account

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1013
Author(s):  
Vivian H. Tran ◽  
Andries A. Temme ◽  
Lisa A. Donovan
Keyword(s):  
Helianthus Annuus ◽  
Salinity Tolerance ◽  
Osmotic Adjustment ◽  
Abiotic Stress Tolerance ◽  
Wild Relatives ◽  
Elemental Content ◽  
Growth Responses ◽  
Helianthus Annuus L ◽  
Trade Offs ◽  
Wild Accessions

Cultivated crops are expected to be less stress tolerant than their wild relatives, leading to efforts to mine wild relatives for traits to increase crop tolerance. However, empirical tests of this expectation often confound tolerance with plant vigor. We assessed whether wild and cultivated Helianthus annuus L. differed for salinity tolerance with 0 and 150 mM NaCl treatments. Salinity tolerance was assessed as the proportional reduction in biomass and as the deviation from expected performance based on vigor. Cultivated accessions had a greater proportional decline in biomass than wild accessions, but proportional decline was positively associated with vigor in both. Thus, wild and cultivated H. annuus did not differ for tolerance when variation in vigor was corrected for statistically. For traits potentially related to tolerance mechanisms, wild and cultivated accessions differed for elemental content and allocation of N, P, K, Mg, Ca, S, Na, Fe, Mn, B, Cu, and Zn for some tissues, biomass allocation, specific leaf area, and leaf succulence. However, these traits were generally unrelated to tolerance corrected for vigor. Osmotic adjustment was associated with tolerance corrected for vigor only in wild accessions where more osmotic adjustment was associated with greater tolerance. Our results for H. annuus suggest that efforts to use wild relatives to enhance crop abiotic stress tolerance will benefit from greater knowledge of traits related to plant growth responses decoupled from vigor, in order to get beyond potential growth-tolerance trade-offs.

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