Water relations and gas exchange of tropical saplings during a prolonged drought in a Bornean heath forest, with reference to root architecture

2000 ◽  
Vol 16 (1) ◽  
pp. 101-116 ◽  
Author(s):  
Kun-fang Cao
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Status ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Deep Roots ◽  
Lower Maximum ◽  
Osmotic Acclimation ◽  
Heath Forest ◽  
Osmotic Potentials

Leaf water and osmotic potentials and gas exchange were monitored during a prolonged El Niño drought in 1998 for saplings of seven species in a Bornean heath forest and compared with measurements taken during a subsequent wet period. The four dipterocarp species maintained reasonably good water status throughout the drought, especially Dipterocarpus borneensis which had thick and deep tap roots. In contrast, two of three non-dipterocarp species, Cleistanthus baramicus and Tristaniopsis obovata displayed predawn leaf water potentials approaching their turgor-loss points. During the drought, all species except D. borneensis displayed strongly reduced stomatal conductance after a brief exposure to sun, and all displayed lower maximum rates of stomatal conductance and net photosynthesis than during the wet period. Only Cotylelobium burckii displayed significant osmotic acclimation to the drought. T. obovata possessing a superficial root system suffered a high mortality due to the drought, but recovered faster after the first rains than the other species all of which had tap roots. Deep roots and strong stomatal control favour trees in tropical heath forests where water deficits probably occur regularly.

scholarly journals Photosynthesis and Leaf Water, Carbohydrate, and Hormone Status during Rooting of Stem Cuttings of Acer rubrum

1991 ◽  
Vol 116 (6) ◽  
pp. 1052-1057 ◽  
Author(s):  
T.J. Smalley ◽  
M.A. Dirr ◽  
A.M. Armitage ◽  
B.W. Wood ◽  
R.O. Teskey ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Status ◽  
Soluble Sugars ◽  
Acer Rubrum ◽  
Net Photosynthesis ◽  
Zeatin Riboside ◽  
Leaf Water ◽  
Stem Cuttings ◽  
Leaf Water Status ◽  
Photosynthetic Rates

Leaf water status, carbohydrate levels, net photosynthesis, stomatal conductance, ABA, dihydrozeatin riboside (DHZR), and trans-zeatin riboside (ZR) levels were determined in a greenhouse during rooting of stem cuttings of Acer rubrum L. `Red Sunset' taken on 3 Sept. 1987 and 28 May 1988. Leaf water status deteriorated before rooting and improved after root emergence. Leaf carbohydrate concentrations (glucose, sucrose, total soluble sugars, and total carbohydrates) increased until rooting and decreased after rooting, while changes in starch concentrations were trendless. ABA levels increased after insertion of cuttings into the rooting medium, but decreased before rooting. No correlation between timing of rooting and concentrations of the cytokinins ZR or DHZR was observed. Photosynthetic rates during rooting were higher for the Sept. 1987 cuttings and did not decrease to the compensation point as did those for May 1988 cuttings. Low photosynthetic rates and stomatal conductance of the cuttings during rooting were associated with water stress. The relationship between photosynthetic rates of such cuttings and cytokinin (CK) or ABA content was unclear. Chemical names used: [S-(Z,E]-5-(1-hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-2, 4-pentadienoic acid (abscisic acid, ABA); 2-methyl-4-(1H-purin-6-ylamino)-2-buten-1-ol (zeatin, Z).

scholarly journals Physiological responses of beet plants irrigated with saline water and silicon application

2020 ◽  
Vol 11 ◽  
pp. E3113
Author(s):  
José Sebastião de Melo Filho ◽  
Toshik Iarley da Silva ◽  
Anderson Carlos de Melo Gonçalves ◽  
Leonardo Vieira de Sousa ◽  
Mario Leno Martins Véras ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Concentration ◽  
Saline Water ◽  
Block Design ◽  
Essential Element ◽  
Net Photosynthesis ◽  
Crop Productivity ◽  
Experimental Unit ◽  
Randomized Block Design

Although not considered an essential element, silicon can be used to increase crop productivity, especially under stress conditions. In this sense, the objective was to evaluate the gas exchange of beet plants irrigated with saline water depending on the application of silicon. The experiment was conducted in a randomized block design, in a 5 x 5 factorial, referring to five levels of electrical conductivity of irrigation water (ECw): (0.5; 1.3; 3.25; 5.2 and 6.0 dS m-1) and five doses of silicon (0.00; 2.64; 9.08; 15.52 and 18.16 mL L-1), with six beet plants as an experimental unit. The effect of treatments on beet culture was evaluated at 30 and 60 days after irrigation with saline water from measurements of internal carbon concentration, stomatal conductance, net photosynthesis rate, instantaneous water use efficiency and instantaneous carboxylation efficiency using the LCpro+Sistem infrared gas analyzer (IRGA). Irrigation with saline water reduced the gas exchange of beet plants at 60 days after irrigation, but at 30 days after irrigation, the use of saline water increased stomatal conductance, transpiration rate and internal carbon concentration. The application of silicon decreased stomatal conductance, internal carbon concentration and efficiency in the use of water, but increased the rate of net photosynthesis, the rate of transpiration and instantaneous efficiency of carboxylation at 30 and 60 days after irrigation.

Relationship Between Root/Soil Hydraulic Properties and Stomatal Behaviour in Sugarcane

1989 ◽  
Vol 16 (3) ◽  
pp. 241 ◽  
Author(s):  
NZ Saliendra ◽  
FC Meinzer
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Water Status ◽  
Hydraulic Conductance ◽  
Leaf Water ◽  
Soil Drying ◽  
Root Hydraulic Conductance ◽  
High Soil Moisture

Stomatal conductance, leaf and soil water status, transpiration, and apparent root hydraulic conductance were measured during soil drying cycles for three sugarcane cultivars growing in containers in a greenhouse. At high soil moisture, transpiration and apparent root hydraulic conductance differed considerably among cultivars and were positively correlated, whereas leaf water potential was similar among cultivars. In drying soil, stomatal and apparent root hydraulic conductance approached zero over a narrow (0.1 MPa) range of soil water suction. Leaf water potential remained nearly constant during soil drying because the vapor phase conductance of the leaves and the apparent liquid phase conductance of the root system declined in parallel. The decline in apparent root hydraulic conductance with soil drying was manifested as a large increase in the hydrostatic pressure gradient between the soil and the root xylem. These results suggested that control of stomatal conductance in sugarcane plants exposed to drying soil was exerted primarily at the root rather than at the leaf level.

The impact of kaolin clay sprays on leaf gas exchange of Ginger Gold apple trees in New Brunswick

2006 ◽  
Vol 86 (Special Issue) ◽  
pp. 1377-1381 ◽  
Author(s):  
J. P. Privé ◽  
L. Russell ◽  
A. LeBlanc
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
New Brunswick ◽  
Leaf Gas Exchange ◽  
Net Photosynthesis ◽  
Apple Orchard ◽  
Kaolin Clay ◽  
Gas Exchange Parameters ◽  
Leaf Physiology ◽  
The Impact

A field trial was conducted over two growing seasons in a Ginger Gold apple orchard in Bouctouche, New Brunswick, Canada to examine the impact of Surround (95% kaolin clay) on leaf gas exchange [net photosynthesis (Pn), stomatal conductance (gs), intercellular CO2 (Ci) and transpiration (E)]. In 2004, a greater rate of Pn and gs was achieved at the higher than at the lower frequency of Surround applications. This was particularly notable at leaf temperatures exceeding 35°C. In 2005, no significant (P ≤ 0.05) differences among leaf residue groupings [Trace (< 0.5 g m-2), Low (0.5 to 2 g m-2), and High (≥ 2 g m-2)] were found for the four leaf gas exchange parameters at leaf temperatures ranging from 25 to 40°C. It would appear that under New Brunswick commercial orchard conditions, the application of Surround favours or has no effect on leaf gas exchange. Key words: Surround, particle film, leaf physiology, photosynthesis, stomatal conductance, intercellular CO2, transpiration

Effect of Water Stress on Stomatal Conductance and Leaf Water Relations of Leaves Along Current-Year Branches of Peach

1989 ◽  
Vol 16 (6) ◽  
pp. 549 ◽  
Author(s):  
SL Steinberg ◽  
MJ Mcfarland ◽  
JC Miller
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Status ◽  
Stomatal Closure ◽  
Water Flux ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Mature Leaves ◽  
Water Potentials

A gradation, that reflects the maturity of the leaves, exists in the leaf water, osmotic and turgor potential and stomatal conductance of leaves along current and 1-year-old branches of peach. Predawn leaf water potentials of immature folded leaves were approximately 0.24 MPa lower than mature leaves under both well-watered and dry conditions. During the daytime the leaf water potential of immature leaves reflected the water potential produced by water flux for transpiration. In well- watered trees, mature and immature unfolded leaves had a solute potential at least 0.5 MPa lower than immature folded leaves, resulting in a turgor potential that was approximately 0.8 MPa higher. The turgor requirement for growth appeared to be much less than that maintained in mature leaves. As water stress developed and leaf water potentials decreased, the osmotic potential of immature folded leaves declined to the level found in mature leaves, thus maintaining turgor. In contrast, mature leaves showed little evidence of turgor maintenance. Stomatal conductance was lower in immature leaves than in fully mature leaves. With the onset of water stress, conductance of mature leaves declined to a level near that of immature leaves. Loss of turgor in mature leaves may be a major factor in early stomatal closure. It was concluded that osmotic adjustment played a role in maintenance of a leaf water status favorable for some growth in water-stressed immature peach leaves.

The interplay between irrigation and fruiting on branch growth and mortality, gas exchange and water relations of coffee trees

2020 ◽  
Author(s):  
Wellington L Almeida ◽  
Rodrigo T Ávila ◽  
Junior P Pérez-Molina ◽  
Marcela L Barbosa ◽  
Dinorah M S Marçal ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Stomatal Density ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Co2 Concentration ◽  
Plant Hydraulics ◽  
Branch Growth ◽  
Source To Sink ◽  
Leaf Transpiration

Abstract The overall coordination between gas exchanges and plant hydraulics may be affected by soil water availability and source-to-sink relationships. Here we evaluated how branch growth and mortality, leaf gas exchange and metabolism are affected in coffee (Coffea arabica L.) trees by drought and fruiting. Field-grown plants were irrigated or not, and maintained with full or no fruit load. Under mild water deficit, irrigation per se did not significantly impact growth but markedly reduced branch mortality in fruiting trees, despite similar leaf assimilate pools and water status. Fruiting increased net photosynthetic rate in parallel with an enhanced stomatal conductance, particularly in irrigated plants. Mesophyll conductance and maximum RuBisCO carboxylation rate remained unchanged across treatments. The increased stomatal conductance in fruiting trees over nonfruiting ones was unrelated to internal CO2 concentration, foliar abscisic acid (ABA) levels or differential ABA sensitivity. However, stomatal conductance was associated with higher stomatal density, lower stomatal sensitivity to vapor pressure deficit, and higher leaf hydraulic conductance and capacitance. Increased leaf transpiration rate in fruiting trees was supported by coordinated alterations in plant hydraulics, which explained the maintenance of plant water status. Finally, by preventing branch mortality, irrigation can mitigate biennial production fluctuations and improve the sustainability of coffee plantations.

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 Parameterization of a coupled CO<sub>2</sub> and H<sub>2</sub>O gas exchange model at the leaf scale of <i>Populus euphratica</i>

2010 ◽  
Vol 14 (3) ◽  
pp. 419-431 ◽  
Author(s):  
G. F. Zhu ◽  
X. Li ◽  
Y. H. Su ◽  
C. L. Huang
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Electron Transport Rate ◽  
Populus Euphratica ◽  
Coupled Model ◽  
Net Photosynthesis ◽  
Combined Model ◽  
Validation Data ◽  
Bisphosphate Carboxylase ◽  
Diurnal Patterns

Abstract. The following two models were combined to simultaneously predict CO2 and H2O gas exchange at the leaf scale of Populus euphratica: a Farquhar et al. type biochemical sub-model of photosynthesis (Farquhar et al., 1980) and a Ball et al. type stomatal conductance sub-model (Ball et al., 1987). The photosynthesis parameters [including maximum carboxylation rate allowed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), potential light-saturated electron transport rate (Jmax), triose phosphate utilization (TPU) and day respiration (Rd)] were determined by using the genetic algorithm (GA) method based on A/Ci data. Values of Vcmax and Jmax standardized at 25 °C were 75.09±1.36 (mean ± standard error), 117.27±2.47, respectively. The stomatal conductance sub-model was calibrated independently. Prediction of net photosynthesis by the coupled model agreed well with the validation data, but the model tended to underestimate transpiration rates. Overall, the combined model generally captured the diurnal patterns of CO2 and H2O exchange resulting from variation in temperature and irradiation.

scholarly journals Foliar water‐uptake strategies are related to leaf water status and gas exchange in plants from a ferruginous rupestrian field

2019 ◽  
Vol 106 (7) ◽  
pp. 935-942 ◽  
Author(s):  
Daniela Boanares ◽  
Alessandra R. Kozovits ◽  
José P. Lemos‐Filho ◽  
Rosy M. S. Isaias ◽  
Ricardo R. R. Solar ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Water Uptake ◽  
Water Status ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Foliar Water Uptake
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