scholarly journals IS ABSCISIC ACID INVOLVED IN THE DROUGHT RESPONSES OF BRAZILIAN GREEN DWARF COCONUT?

2009 ◽  
Vol 45 (2) ◽  
pp. 189-198 ◽  
Author(s):  
F. P. GOMES ◽  
M. A. OLIVA ◽  
M. S. MIELKE ◽  
A-A. F. DE ALMEIDA ◽  
H. G. LEITE ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Water Use ◽  
Severe Drought ◽  
Use Efficiency ◽  
Recovery Cycles ◽  
Mild Drought

SUMMARYAbscisic acid (ABA) accumulation in leaves of drought-stressed coconut palms and its involvement with stomatal regulation of gas exchange during and after stress were investigated. Two Brazilian Green Dwarf coconut ecotypes from hot/humid and hot/dry environments were submitted to three consecutive drying/recovery cycles under greenhouse conditions. ABA accumulated in leaflets before significant changes in pre-dawn leaflet water potential (ΨPD) and did not recover completely in the two ecotypes after 8 days of rewatering. Stomatal conductance was influenced by ABA under mild drought and by ΨPD under severe drought. There were no significant differences between the ecotypes for most variables measured. However, the ecotype from a hot/dry environment showed higher water use efficiency after repeated cycles of water stress.

scholarly journals Interaction of CO<sub>2</sub> concentrations and water stress in semiarid plants causes diverging response in instantaneous water use efficiency and carbon isotope composition

2017 ◽  
Vol 14 (14) ◽  
pp. 3431-3444 ◽  
Author(s):  
Na Zhao ◽  
Ping Meng ◽  
Yabing He ◽  
Xinxiao Yu
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Environmental Changes ◽  
Isotope Composition ◽  
Water Soluble ◽  
Severe Drought ◽  
Semiarid Areas ◽  
Use Efficiency

Abstract. In the context of global warming attributable to the increasing levels of CO2, severe drought may be more frequent in areas that already experience chronic water shortages (semiarid areas). This necessitates research on the interactions between increased levels of CO2 and drought and their effect on plant photosynthesis. It is commonly reported that 13C fractionation occurs as CO2 gas diffuses from the atmosphere to the substomatal cavity. Few researchers have investigated 13C fractionation at the site of carboxylation to cytoplasm before sugars are exported outward from the leaf. This process typically progresses in response to variations in environmental conditions (i.e., CO2 concentrations and water stress), including in their interaction. Therefore, saplings of two typical plant species (Platycladus orientalis and Quercus variabilis) from semiarid areas of northern China were selected and cultivated in growth chambers with orthogonal treatments (four CO2 concentration ([CO2])  ×  five soil volumetric water content (SWC)). The δ13C of water-soluble compounds extracted from leaves of saplings was determined for an assessment of instantaneous water use efficiency (WUEcp) after cultivation. Instantaneous water use efficiency derived from gas-exchange measurements (WUEge) was integrated to estimate differences in δ13C signal variation before leaf-level translocation of primary assimilates. The WUEge values in P. orientalis and Q.  variabilis both decreased with increased soil moisture at 35–80 % of field capacity (FC) and increased with elevated [CO2] by increasing photosynthetic capacity and reducing transpiration. Instantaneous water use efficiency (iWUE) according to environmental changes differed between the two species. The WUEge in P. orientalis was significantly greater than that in Q. variabilis, while an opposite tendency was observed when comparing WUEcp between the two species. Total 13C fractionation at the site of carboxylation to cytoplasm before sugar export (total 13C fractionation) was species-specific, as demonstrated in the interaction of [CO2] and SWC. Rising [CO2] coupled with moistened soil generated increasing disparities in δ13C between water-soluble compounds (δ13CWSC) and estimates based on gas-exchange observations (δ13Cobs) in P. orientalis, ranging between 0.0328 and 0.0472 ‰. Differences between δ13CWSC and δ13Cobs in Q. variabilis increased as [CO2] and SWC increased (0.0384–0.0466 ‰). The 13C fractionation from mesophyll conductance (gm) and post-carboxylation both contributed to the total 13C fractionation that was determined by δ13C of water-soluble compounds and gas-exchange measurements. Total 13C fractionation was linearly dependent on stomatal conductance, indicating that post-carboxylation fractionation could be attributed to environmental variation. The magnitude and environmental dependence of apparent post-carboxylation fractionation is worth our attention when addressing photosynthetic fractionation.

scholarly journals Estimation of Leaf Water Use Efficiency Threshold Values for Water Stress in Winter Wheat (Triticum aestivum L.)

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qiu Xinqiang ◽  
Zhang Yushun ◽  
Qin Haixia ◽  
Wang Min ◽  
Wang Yanping ◽  
...  
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Winter Wheat ◽  
Water Use ◽  
Growth Stage ◽  
Severe Drought ◽  
Threshold Values ◽  
Gas Exchange Parameters ◽  
Use Efficiency ◽  
Exchange Parameters

Drought significantly threatens crop productivity and food security worldwide. However, the severity of drought is predicted to increasingly intensify in the future. To provide an antidrought strategy for farmers and breeders, the response of stomatal behavior of crops to water stress should be well studied. In this study, a lysimeter experiment was conducted to study the relationship between gas exchange parameters and grain yields of winter wheat. Light, moderate, and severe drought levels were imposed at seedling, jointing, heading, and filling stages. The results showed that crop evapotranspiration (ETc, mm) of winter wheat during the entire growing season was limited by drought imposed at any growth stage, and ETc under severe drought treatment was always the lowest. The stomatal limitation value had a significant linear correlation with the stomatal conductance (Gs, μmol mol H2O m–2 s–1) and transpiration rate (Tr, mmol H2O m–2 s–1). Light and moderate drought levels at the seedling stage did not generate irreversible physiological stress on wheat plants, while severe drought at any growth stage caused significant reduction in gas exchange parameters and grain yields. Theoretical threshold values of leaf water use efficiency (WUEl) for light, moderate, and severe drought levels were 2.62, 3.36, and 4.11 μmol mmol–1, respectively. The threshold values are useful to provide theoretical reference for achieving smart irrigation in the North China Plain.

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.

Boron Supply and Water Deficit Consequences in Young Paricá (Schizolobium parahyba var. amazonicum) Plants

2016 ◽  
Vol 44 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Bianca do Carmo SILVA ◽  
Pêola Reis de SOUZA ◽  
Daihany Moraes CALLEGARI ◽  
Vanessa Ferreira ALVES ◽  
Allan Klynger da Silva LOBATO ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Deficit ◽  
Water Use ◽  
Electrolyte Leakage ◽  
Tolerance Mechanism ◽  
Schizolobium Parahyba ◽  
Use Efficiency

Boron (B) is a very important nutrient required by forest plants; when supplied in adequate amounts, plants can ameliorate the negative effects of abiotic stresses. The objective of this study was to (i) investigate gas exchange, (ii) measure oxidant and antioxidant compounds, and (iii) respond how B supply acts on tolerance mechanism to water deficit in young Schizolobium parahyba plants. The experiment employed a factorial that was entirely randomised, with two boron levels (25 and 250 µmol L-1, simulating conditions of sufficient B and high B, respectively) and two water conditions (control and water deficit). Water deficit induced negative modifications on net photosynthetic rate, stomatal conductance and water use efficiency, while B high promoted intensification of the effects on stomatal conductance and water use efficiency. Hydrogen peroxide and electrolyte leakage of both tissues suffered non-significant increases after B high and when applied water deficit. Ascorbate levels presented increases after water deficit and B high to leaf and root. Our results suggested that the tolerance mechanism to water deficit in young Schizolobium parahyba plants is coupled to increases in total glutathione and ascorbate aiming to control the overproduction of hydrogen peroxide and alleviates the negative consequences on electrolyte leakage and gas exchange. In relation to B supply, this study proved that sufficient level promoted better responses under control and water deficit conditions.

Response of greenhouse-grown bell pepper (Capsicum annuum L.) to variable irrigation

2014 ◽  
Vol 94 (2) ◽  
pp. 303-310 ◽  
Author(s):  
Olanike Aladenola ◽  
Chandra Madramootoo
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
Capsicum Annuum ◽  
Water Use ◽  
Irrigation Water ◽  
Bell Pepper ◽  
Marketable Yield ◽  
Capsicum Annuum L ◽  
Use Efficiency

Aladenola, O. and Madramootoo, C. 2014. Response of greenhouse-grown bell pepper (Capsicum annuum L.) to variable irrigation. Can. J. Plant Sci. 94: 303–310. In order to optimize water use in bell pepper production information about the appropriate irrigation water applications and agronomic and physiological response to mild and severe water stress is necessary. Different water applications were tested on yield, quality and water stress threshold of greenhouse-grown bell pepper (Capsicum annuum L.) cultivar Red Knight in 2011 and 2012 on the Macdonald Campus of McGill University, Ste Anne De Bellevue, QC. The study was carried out on a soil substrate in the greenhouse. Irrigation was scheduled with four treatments:120% (T1), 100% (T2), 80% (T3), and 40% (T4) replenishment of crop evapotranspiration in a completely randomized design. The highest marketable yield, water use efficiency and irrigation water use efficiency were obtained with T1 in both years. T1 received 20% more water than T2 to produce 23% more marketable yield than T2. Fruit total soluble solids content was highest in T4, and smallest in T1. The mean crop water stress index (CWSI) of the irrigation treatments ranged between 0.08 and 1.18. Leaf stomatal conductance of bell pepper was 75 to 80% lower in T4 than in T1. Regression obtained between stomatal conductance and CWSI resulted in a polynomial curve with coefficients of determination of 0.88 and 0.97 in 2011 and 2012, respectively. The result from this study indicate that the yield derived justifies the use of an extra quantity of water. Information from this study will help water regulators to make appropriate decision about water to be allocated for greenhouse production of bell pepper.

scholarly journals Variability among Young Table Grape Cultivars in Response to Water Deficit and Water Use Efficiency

Agronomy ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 135 ◽  
Author(s):  
Carolin Weiler ◽  
Nikolaus Merkt ◽  
Jens Hartung ◽  
Simone Graeff-Hönninger
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Deficit ◽  
Water Use ◽  
Dry Mass ◽  
Table Grape ◽  
Water Limitation ◽  
Use Efficiency ◽  
Response To Water ◽  
Grape Cultivars

Climate change will lead to higher frequencies and durations of water limitations during the growing season, which may affect table grape yield. The aim of this experiment was to determine the variability among 3-year old table grape cultivars under the influence of prolonged water deficit during fruit development on gas exchange, growth, and water use efficiency. Six own rooted, potted table grape cultivars (cv. ‘Muscat Bleu’, ‘Fanny’, ‘Nero’, ‘Palatina’, ‘Crimson Seedless’ and ‘Thompson Seedless’) were subjected to three water deficit treatments (Control treatment with daily irrigation to 75% of available water capacity (AWC), moderate (50% AWC), and severe water deficit treatment (25% AWC)) for three consecutive years during vegetative growth/fruit development. Water deficit reduced assimilation, stomatal conductance, and transpiration, and increased water use efficiencies (WUE) with severity of water limitation. While leaf area and number of leaves were not affected by treatments in any of the tested cultivars, the response of specific leaf area to water deficit depended on the cultivar. Plant dry mass decreased with increasing water limitation. Overall, high variability of cultivars to gas exchange and water use efficiencies in response to water limitation was observed. ’Palatina’ was the cultivar having a high productivity (high net assimilation) and low water use (low stomatal conductance) and the cultivar ‘Fanny’ was characterized by the highest amount of total annual dry mass as well as the highest total dry mass production per water supplied during the experiment (WUEDM). Hence, ‘Fanny’ and ‘Palatina’ have shown to be cultivars able to cope with water limiting conditions and should be extensively tested in further studies.

Comparative forage yield, water use, and water use efficiency of alfalfa, crested wheatgrass and spring wheat in a semiarid climate in southern Saskatchewan

2005 ◽  
Vol 85 (4) ◽  
pp. 877-888 ◽  
Author(s):  
Paul G. Jefferson ◽  
Herb W. Cutforth
Keyword(s):  
Water Stress ◽  
Water Use Efficiency ◽  
Water Potential ◽  
Soil Water ◽  
Water Use ◽  
Spring Wheat ◽  
Forage Yield ◽  
Forage Crops ◽  
Crested Wheatgrass ◽  
Use Efficiency

Crested wheatgrass (Agropyron cristatum L. Gaertn.) and alfalfa (Medicago sativa L.) are introduced forage species used for hay and grazing by cattle across western Canada. These species are well adapted to the semiarid region but their long-term responses to water stress have not been previously compared. Two alfalfa cultivars with contrasting root morphology (tap-rooted vs. creeping-rooted) and two crested wheatgrass (CWG) cultivars with different ploidy level (diploid vs. tetraploid) were compared with continuously cropped spring wheat (Triticum aestivum L.) for 6 yr at a semiarid location in western Canada. Soil water depletion, forage yield, water use efficiency, leaf water potential, osmotic potential and turgor were compared. There were no consistent differences between cultivars within alfalfa or CWG for variables measured. However, these two species exhibit different water stress response strategies. Leaf water potential of CWG was lower during midday stress period than that of alfalfa or wheat. Alfalfa apparently had greater capacity to osmotically adjust to avoid midday water stress and maintain higher turgor. Soil water use patterns changed as the stands aged. In the initial years of the trial, forage crops used soil water from upper layers of the profile. In later years, soil water was depleted down to 3 m by alfalfa and to 2 m by crested wheatgrass. Alfalfa was able to deplete soil water to lower concentrations than crested wheatgrass or wheat. Soil water depletion by wheat during the non-active growth season (after harvest to fall freeze-up) was much less than for CWG or alfalfa as expected for annual vs. perennial crops. As a result, more soil water was available to wheat during its active growth period. In the last 3 yr, the three species depleted all available soil water. Forage yield responses also changed over time. In the initial 3 yr, crested wheatgrass yielded as much as or more than alfalfa. For the last 3 yr of the experiment, alfalfa yielded more forage than crested wheatgrass. Forage crops deplete much more soil water during periods of aboveground growth dormancy than wheat. Water use efficiency of crested wheatgrass declined with stand age compared with fertilized continuous spring wheat. Alfalfa exhibited deep soil water extraction and apparent osmotic adjustment in response to water stress while CWG exhibited tolerance of low water potential during stress. Key words: forage yield, soil water, water potential, water use, water use efficiency, drought

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