scholarly journals Gas Exchange, Water Relations, and Dry Weight Partitioning during Root Initiation and Development of Poinsettia Cuttings

1995 ◽  
Vol 120 (3) ◽  
pp. 454-459 ◽  
Author(s):  
Sven E. Svenson ◽  
Fred T. Davies ◽  
Sharon A. Duray
Keyword(s):  
Gas Exchange ◽  
Water Relations ◽  
Adventitious Roots ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Dry Mass ◽  
Root Primordia ◽  
Root Numbers ◽  
Relative Water ◽  
Dry Weight Partitioning

Gas exchange, water relations, and dry weight partitioning of shoot tip cuttings of `Eckespoint Lilo Red' (`Lilo') and `Gutbier V-10 Amy Red' (`Amy') poinsettia (Euphorbia pulcherrima Wind. ex Klotzsch) were studied during the initiation and development of adventitious roots. Net photosynthesis (A) and stomatal conductance (g) of cuttings were initially low and remained low until root primordia formation. Foliar relative water content (RWC) and osmotic potential (ψπ) increased upon formation of root primordia. Following formation of root primordia (2 days before visible root emergence) and concurrent with increasing RWC and ψπ, g increased. As roots initially emerged, A and g increased rapidly and continued to increase with further root primordia development and subsequent emergence of adventitious roots. Cutting stem and leaf dry mass and leaf area increased during the first few days after sticking cuttings. During primordium development and initial root emergence, the highest percent increase in dry weight was accounted for by basal stem sections. AU cuttings of both cultivars rooted and had similar root numbers after 23 days, but `Lilo' cuttings had 15% better rooting and 44% more roots than `Amy' after 15 days. This research supports the hypothesis that formation and elongation of root primordia coincides with increased gas exchange in poinsettia cuttings, and that gas exchange can be used as a nondestructive indicator of adventitious root development.

scholarly journals 143 Gas Exchange, Water Relations, and Growth of Seaside Alder Exposed to Drought and Flooding

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 414C-414
Author(s):  
William R. Graves ◽  
Sarah J. Gardner
Keyword(s):  
Gas Exchange ◽  
Moisture Content ◽  
Water Relations ◽  
Soil Profile ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Stem Water Potential ◽  
Shoot Dry Weight ◽  
Effects Of Drought ◽  
Seaside Alder

Alnus maritima [Marsh.] Nutt. (seaside alder) is a rare species that occurs naturally only on soils that are frequently or constantly saturated with fresh water. The objective of our first experiment was to determine effects of drought and flooding treatments of differing severity on foliar gas exchange, water relations, and development of plants grown in containers in a greenhouse. In a second experiment we examined how the rate of water loss from soil during drought episodes affected the gas exchange and survival of leaves. In the first experiment, changes in soil moisture content, which ranged from saturation to 10% or less by volume across treatments, were associated with altered stem water potential and net photosynthesis. Analysis of the osmolarity of liquid extracted from leaves indicated that osmotic adjustment did not occur in response to drought. Shoot dry weight per plant ranged from over 7 g (only the lower portion of the soil profile kept saturated) to less than 3 g (entire soil profile constantly saturated). Episodes of drought of different severity led to plants with shoots that weighed between these two extremes, and exposure to soils with 10% water or less by volume did not elicit leaf desiccation or abscission. Results of the second experiment suggest that leaf desiccation can result from exposing plants to 10% water or less by volume if the drought develops rapidly in a small volume of soil. We conclude that, despite the niche it occupies in nature, seaside alder may have the potential to be used in managed landscapes with soils that vary in moisture content.

scholarly journals 206 Growth, Gas Exchange, and Water Relations of Micropropagated Chile Ancho Pepper (Capsicum annuum L. cv. San Luis) Plantlets during Acclimatization and Post-acclimatization

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 426D-426 ◽  
Author(s):  
Andres A. Estrada-Luna ◽  
Fred T. Davies ◽  
Jonathan N. Egilla
Keyword(s):  
Gas Exchange ◽  
Capsicum Annuum ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Dry Mass ◽  
Ex Vitro ◽  
San Luis ◽  
Transplant Shock ◽  
Relative Water

Micropropagated chile ancho pepper (Capsicum annuum L. cv. San Luis) plants were transferred to ex vitro conditions to study plantlet performance and selected physiological changes that occur during acclimatization and post-acclimatization. The physiology of the plantlets was characterized by measuring leaf gas exchange and water status. Plant growth was determined by assessing plant height, leaf number, total leaf area, relative growth rate (RGR), and leaf, root, and stem dry mass. Measurements were taken at 0, 1, 2, 3, 6, 12, and 24 days after transplanting. After initial transplanting ex vitro to liner pots with soilless media, plantlet wilting was observed that correlated with reduced leaf relative water content (RWC). Water stress was partially alleviated by a reduction in stomatal conductance (gs), confirming that the in vitro formed stomata were functional and able to regulate transpiration (E) to minimize desiccation losses. Because of this stomatal control, plantlets had minimal transplant shock, recovered, and survived. Prior to transplanting, micropropagated plantlets showed heterotrophic/mixotrophic characteristics as indicated by low photosynthesis [(A) 4.74 μmol·m2·s-1]. During acclimatization, RWC, gs, E, and A were significantly lower 2 days after transplanting. However, within 6 days after transplanting, plantlets recovered and became autotrophic, attaining high A (16.3 μmol·m-2·s-1), gs, and E. The stabilization and improvement of plantlet water status and gas exchange during acclimatization and post-acclimatization closely correlated with dramatic increases in plantlet growth.

scholarly journals Flooding Reduces Gas Exchange and Growth in Snap Bean

HortScience ◽  
1991 ◽  
Vol 26 (4) ◽  
pp. 372-373 ◽  
Author(s):  
Bharat P. Singh ◽  
Kevin A. Tucker ◽  
James D. Sutton ◽  
Harbans L. Bhardwaj
Keyword(s):  
Gas Exchange ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Quadratic Model ◽  
Snap Bean ◽  
Blue Lake ◽  
Relationship Of ◽  
The Relationship ◽  
Best Fit ◽  
Prior Stress

This study was conducted to determine the effect of various flooding durations on the growth, water relations, and photosynthesis of the snap bean (Phaseolus vulgaris L.). Greenhouse-grown plants of cv. Blue Lake 274 were flooded for 0 (control), 1, 3, 5, or 7 days. Leaf water potential (ψ), stomatal conductance (gs), transpiration (E), and net photosynthesis (Pn) were measured at the completion of the flooding period and after recovery for 7 days. Root, stem, and leaf dry weights were recorded after plants were allowed to recover from the flooding stress for 7 days. The values for ψ, gs, E, and Pn decreased quadratically with the increase in the duration of flooding. The Pn of plants flooded for 1 day was 17% lower than that of the control and it reached near zero in plants flooded for 7 days. The decrease in Pn after 1 day of flooding was not associated with ψ or gs; however, for longer duration of flooding, Pn decline coincided with the decline in gs. A week after the cessation of flooding, the level of recovery in ψ, E, and Pn was linear and that in gs quadratic to the duration of prior stress experienced by the plant. However, after recovering for 7 days, none of the flooded plants regained gas exchange activities at par with the control. The relationship of stem dry weight to duration of flooding was linear, while a quadratic model provided the best fit for the regression of root and leaf dry weight on the number of days of flooding. Overall, even 1 day of flooding reduces photosynthesis in snap bean and causes a decrease in dry weight of the plant. the extent of decrease in both increasing with the duration of flooding.

scholarly journals Effect of fertigation with potassium and nitrogen on gas exchange and biomass accumulation in eggplant1

2017 ◽  
Vol 47 (3) ◽  
pp. 345-352
Author(s):  
Álvaro Henrique Cândido de Souza ◽  
Roberto Rezende ◽  
Marcelo Zolin Lorenzoni ◽  
Fernando André Silva Santos ◽  
André Maller
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Use ◽  
Biomass Accumulation ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Co2 Concentration ◽  
Internal Co2 ◽  
Use Efficiency ◽  
Total Dry Weight

ABSTRACT Adequate crop fertilization is one of the challenges for agriculture. Measuring gas exchange and biomass accumulation may be used to adjust crop management. The effect of fertigation with potassium (0 kg ha-1, 54 kg ha-1, 108 kg ha-1 and 216 kg ha-1) and nitrogen (0 kg ha-1, 67 kg ha-1, 134 kg ha-1 and 268 kg ha-1) on gas exchange and biomass accumulation in eggplant was assessed under greenhouse conditions. The net photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, instantaneous carboxylation efficiency, water-use efficiency and total dry weight were evaluated. With the exception of K for water-use efficiency and N for internal CO2 concentration, all the other gas exchange parameters were significantly affected by the K and N doses. There was an interaction between N and K doses for net photosynthesis, stomatal conductance, transpiration and instantaneous carboxylation efficiency. The highest values for net photosynthesis, stomatal conductance, transpiration rate, carboxylation instantaneous efficiency and total dry weight were found in the range of 125-185 kg ha-1 of K and 215-268 kg ha-1 of N.

scholarly journals Gas exchange, leaf and root dry mass in Bell Pepper under fertigation with nitrogen and potassium

2018 ◽  
Vol 39 (2) ◽  
pp. 511 ◽  
Author(s):  
Marcelo Zolin Lorenzoni ◽  
Roberto Rezende ◽  
Álvaro Henrique Cândido de Souza ◽  
Fernando André Silva Santos ◽  
Cláudia Salim Lozano ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Concentration ◽  
Crop Production ◽  
Interactive Effect ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Bell Pepper ◽  
Carboxylation Efficiency ◽  
Physiological Variables

Bell pepper is a vegetable-fruit of great economic importance in Brazil. Crop production demands adequate water supply, nutrients, and light. The objective of this study was to evaluate gas exchange (net photosynthesis, stomatal conductance, transpiration, internal carbon concentration and instantaneous carboxylation efficiency) and dry mass accumulation in leaves and roots under fertigation with nitrogen and potassium. The experiment was conducted in a completely randomized design in a factorial scheme (4 × 4) with four replications and a total of 64 experimental units. Treatments consisted of a combination of four nitrogen doses (0; 73.4; 146.8 and 293.6 kg ha-1 of N) with four doses of potassium (0; 53.3; 106.7 and 213.4 kg ha-1 of K). An infrared gas analyzer (IRGA) coupled with a light source (irradiation of 600 µmol m-2 s-1) was used for the evaluation of gas exchange. There was a significant interactive effect of N and K on net photosynthesis and leaf and root dry mass. Root dry mass was the variable that best expressed this interaction. Physiological variables measured were more responsive to nitrogen fertilization than to K fertilization. The optimum values of stomatal conductance, transpiration, internal carbon concentration and carboxylation efficiency were obtained with the application of nitrogen doses between 147 and 294 kg ha-1.

Water relations of temperate mistletoes on various hosts

2002 ◽  
Vol 29 (1) ◽  
pp. 89 ◽  
Author(s):  
Graham L. Strong ◽  
Peter Bannister
Keyword(s):  
New Zealand ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Relations ◽  
Daily Minimum ◽  
Relative Water ◽  
Artificial Shading ◽  
Osmotic Potentials ◽  
Moduli Of Elasticity ◽  
Water Contents

The daily field water relations and gas exchange of the temperate mistletoes Ileostylus micranthus (Hook.f.) Tiegh. and Tupeia antarctica Cham. et Schlecht. on various hosts were examined seasonally in Dunedin, New Zealand during 1996–1998. Mistletoes commonly have higher transpiration rates (E) than their hosts, and this is generally cited as the reason why mistletoes develop lower water potentials (ψ) than their hosts. The mistletoe-host pairs that we examined showed no significant overall differences in E and stomatal conductance (g), and we used them to test the hypothesis that lowered ψ in mistletoes result from higher E. Despite the lack of differences in E and g, osmotic potentials, predawn and daily minimum ψ (ψmin) were significantly more negative in mistletoes, although differences between host and mistletoe ψ were less on hosts with low osmotic potentials and ψ. Mistletoes maintained lower ψ than their hosts both when unshaded and under artificial shading, had lower ψ than hosts at equal E, but had shoot hydraulic resistances similar to that of their hosts. E and ψ of hosts and mistletoes tended to be coordinated only in summer, when hosts were most water-stressed. Mistletoes maintained higher relative water contents at turgor loss, symplastic water contents, and bulk moduli of elasticity (ε) than their hosts. We conclude that the lower ψ in these temperate mistletoes are a consequence of greater mistletoe E only when host ψ are low, but are otherwise maintained by greater succulence and higher ε than in their hosts.

Photorespiration and internal recycling of CO2 in the submersed angiosperm Scirpus subterminalis

1980 ◽  
Vol 58 (6) ◽  
pp. 591-598 ◽  
Author(s):  
Morten Søndergaard ◽  
Robert G. Wetzel
Keyword(s):  
Gas Exchange ◽  
Time Course ◽  
Free Water ◽  
Net Photosynthesis ◽  
Open Water ◽  
Dry Weight ◽  
Experimental Conditions ◽  
Gas Exchange Characteristics ◽  
Gas Space ◽  
A Minor

The presence and magnitude of photorespiration in the submersed freshwater angiosperm Scirpus subterminalis Torr. was investigated by gas-exchange characteristics in an open water-flow system. The minimal rates of photorespiration during active photosynthesis were measured by following the time course of differential 14CO2 and 12CO2 uptake. At 8 mg O2 L−1 (equal to oxygen saturation at 20 °C), the rate was 0.4 μg C (mg organic dry weight)−1 h−1, which was about 10% of net photosynthesis under the experimental conditions. Increasing the oxygen concentration to 30 mg O2 L−1, enhanced photorespiration to 30% of net photosynthesis. It was shown that the concentration of oxygen affected net photosynthesis, CO2 evolution into CO2-free water in the light, the post-illumination CO2 burst, and the CO2 compensation point.The effect of the internal gas space on recycling of CO2 was investigated by comparing gas-exchange by intact and sectioned leaves. About 30% of the CO2 of photorespiratory origin was recycled internally within the lacunal system. The gas-exchange characteristics of Scirpus were similar to those observed in terrestrial C3 species although of a minor magnitude and a different time course. The ecological implications of these finds are discussed.

Variation of water relations parameters with extended rehydration time, leaf form, season, and proportion of leaf

1996 ◽  
Vol 26 (2) ◽  
pp. 175-185 ◽  
Author(s):  
Donald B. Zobel
Keyword(s):  
Water Relations ◽  
Dry Mass ◽  
Current Data ◽  
Sampling Location ◽  
Tissue Elasticity ◽  
Leaf Form ◽  
Leaf Dry Mass ◽  
Location Patterns ◽  
Relative Water ◽  
Broadleaf Species

Pressure–volume curves were measured in October, February, and July for twigs of three deciduous, three evergreen broadleaf, four pine, and two other conifer species in the southern Appalachian Mountains, U.S.A. Data were analyzed to determine the influence on water relations parameters of rehydration time, sample leafiness, leaf form, season, and species within leaf form. Results of samples rehydrated overnight did not differ significantly from results of samples rehydrated overnight plus 24 h. Leafiness (leaf dry mass/sample dry mass) was occasionally related to water relations parameters. Water relations parameters usually varied with leaf form, and occasionally with sampling location. Patterns of variation among leaf forms differed for each combination of parameter and season: the strongest generality was that leafy deciduous twigs and pines had high tissue elasticity, whereas evergreen broadleaf species had low elasticity. Evergreen broadleaf species had a consistently high relative water content at zero turgor. Compared with literature values, these species had average to very high osmotic potentials. There was little consistency of water relations parameters among leaf forms and seasons in the overall (literature and current) data, although osmotic potential of all evergreen leaf forms rose from winter to summer.

Salixspecies variation in leaf gas exchange, sodium, and nutrient parameters at three levels of salinity

2017 ◽  
Vol 47 (8) ◽  
pp. 1045-1055 ◽  
Author(s):  
John E. Major ◽  
Alex Mosseler ◽  
John W. Malcolm
Keyword(s):  
Gas Exchange ◽  
Positive Relationship ◽  
Leaf Gas Exchange ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Significant Positive Relationship ◽  
Evolutionary Origins ◽  
Use Efficiency ◽  
The Arid Regions ◽  
Salix Discolor

Leaf gas exchange, Na+, and nutrient parameters were quantified under control (CTL), medium (MST), and high (HST) saline treatments for Salix discolor Muhl. (DIS), Salix eriocephala Michx. (ERI), and Salix interior Rowlee (INT). Net photosynthesis (Pn) increased from CTL to MST for all species but remained unchanged between MST and HST for surviving INT plants in HST. Salix interior had greater water-use efficiency (WUE) than DIS and ERI. Under CTL, INT had 13× the leaf Na+concentration of DIS and ERI, but INT Na+only increased by 17% across each saline treatment, whereas DIS and ERI leaf Na+increased 6.0× from CTL to MST. Salix discolor and ERI had greater cation to Na+ratios than INT; however, INT ratios were stable across saline treatments, whereas the DIS and ERI ratios dropped precipitously. Across species and treatments, Pnhad a significant positive relationship to total aboveground dry mass, supporting the sink regulation of Pntheory. Also, Pnshowed a significant positive relationship to WUE and leaf N and to leaf Na+, which probably reflects greater energy expenditure required to mitigate the higher levels of Na+. The saline tolerance of INT may be due to natural selection pressure in the arid regions of the southwestern United States, where it is believed to have its evolutionary origins.

Growth and ecophysiological responses of black spruce seedlings to elevated CO2 under varied water and nutrient additions

1993 ◽  
Vol 23 (6) ◽  
pp. 1033-1042 ◽  
Author(s):  
Kurt H. Johnsen
Keyword(s):  
Gas Exchange ◽  
Black Spruce ◽  
Seedling Emergence ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Pressure Potential ◽  
Foliar N ◽  
Nutrient Additions ◽  
Xylem Pressure Potential ◽  
Ecophysiological Responses

Two controlled-environment studies examined growth and ecophysiological responses of black spruce (Piceamariana (Mill.) B.S.P.) seedlings to elevated CO2 under varied water and nutrient additions. Growth analyses were conducted followed by measurements of gas exchange, xylem pressure potential and foliar N concentrations. Growth under elevated CO2 (700 ppm) increased final seedling dry weights by 20–48% compared with seedling growth under ambient CO2 (350 ppm). Percent increases in seedling dry weight were greater under drought versus well-watered conditions and higher versus lower nutrient additions. Seedlings grown under elevated CO2 displayed higher water use efficiency than seedlings grown under ambient CO2. This was apparent based upon instantaneous gas exchange as well as xylem potential pressure measurements. Elevated CO2-induced stimulation of relative growth rate was greatest shortly after seedling emergence and decreased with increased seedling size. Acclimation of net photosynthesis was observed and was reversible. Analyses using allometric principles indicate net photosynthetic acclimation resulted from: (i) growth-induced nutrient dilution; (ii) a decrease in foliar N levels not owing to dilution; and (iii) a decrease in net photosynthetic activity.

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