scholarly journals Ecophysiology of coconut palm under water stress

2007 ◽  
Vol 19 (4) ◽  
pp. 377-391 ◽  
Author(s):  
Fábio P. Gomes ◽  
Carlos H.B.A. Prado
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Leaf Gas Exchange ◽  
Coconut Palm ◽  
Morphological Data ◽  
Genotypic Differences ◽  
Holistic View ◽  
Coconut Tree ◽  
Use Efficiency ◽  
The Tropics

Coconut palm is of great social and economic importance for millions of people in the tropics and subtropics. Drought is one of the main environmental factors that limit coconut productivity. In this review, physiological and morphological data are presented in an integrated perspective to provide a holistic view of the behavior of coconut trees facing water deficit under both field and controlled conditions. Great capacity to produce homorhizic roots capable of searching continuously for water and nutrients and high protoplasmic tolerance in leaves allows the coconut tree to endure water deficit. High membrane stability, osmoprotection, osmoregulation and enhanced activity of antioxidant enzymes are characteristics often found in leaves of drought-stressed coconut trees. Information on leaf gas exchange, leaf water potential, water-use efficiency and stomatal behavior was compiled highlighting the differences among cultivars and hybrids under water stress. Genotypic differences in physiological and morphological traits can largely explain the agronomic performance of field-grown coconut trees under drought conditions.

scholarly journals PHYSIOLOGICAL RESPONSES OF DWARF COCONUT PLANTS UNDER WATER DEFICIT IN SALT-AFFECTED SOILS

2017 ◽  
Vol 30 (2) ◽  
pp. 447-457 ◽  
Author(s):  
ALEXANDRE REUBER ALMEIDA DA SILVA ◽  
FRANCISCO MARCUS LIMA BEZERRA ◽  
CLAUDIVAN FEITOSA DE LACERDA ◽  
CARLOS HENRIQUE CARVALHO DE SOUSA ◽  
MARLOS ALVES BEZERRA
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Soil Salinity ◽  
Leaf Gas Exchange ◽  
Coconut Tree ◽  
Salinity Water ◽  
Salt Affected Soils ◽  
Physiological Acclimation ◽  
Adjustment Mechanisms ◽  
Different Levels

ABSTRACT The objective of this study was to characterize the physiological acclimation responses of young plants of the dwarf coconut cultivar Jiqui Green‘ associated with tolerance to conditions of multiple abiotic stresses (drought and soil salinity), acting either independently or in combination. The study was conducted under controlled conditions and evaluated the following parameters: leaf gas exchange, quantum yield of chlorophyll a fluorescence, and relative contents of total chlorophyll (SPAD index). The experiment was conducted under a randomized block experimental design, in a split plot arrangement. In the plots, plants were exposed to different levels of water stress, by imposing potential crop evapotranspiration replacement levels equivalent to 100%, 80%, 60%, 40%, and 20%, whereas in subplots, plants were exposed to different levels of soil salinity (1.72, 6.25, 25.80, and 40.70 dS m-1). Physiological mechanisms were effectively limited when water deficit and salinity acted separately and/or together. Compared with soil salinity, water stress was more effective in reducing the measured physiological parameters. The magnitudes of the responses of plants to water supply and salinity depended on the intensity of stress and evaluation period. The physiological acclimation responses of plants were mainly related to stomatal regulation. The coconut tree has a number of physiological adjustment mechanisms that give the species partial tolerance to drought stress and/or salt, thereby enabling it to revegetate salinated areas, provided that its water requirements are at least partially met.

Sensitivity of leaf gas exchange to atmospheric drought, soil drought, and water-use efficiency in some Mediterranean Abies species

1991 ◽  
Vol 21 (10) ◽  
pp. 1507-1515 ◽  
Author(s):  
J. M. Guehl ◽  
G. Aussenac ◽  
J. Bouachrine ◽  
R. Zimmermann ◽  
J. M. Pennes ◽  
...  
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Leaf Gas Exchange ◽  
Soil Drought ◽  
Drought Adaptation ◽  
Internal Water ◽  
Annual Growth Rings ◽  
Use Efficiency

The responses of CO2 assimilation rate (A), transpiration rate (E), and leaf conductance (g) to increasing leaf to air water vapor concentration difference (ΔW) were investigated (i) using excised shoots from mature trees of Abiesalba, Abiescephalonica, Abiesmarocana, and Abiesnordmanniana and (ii) in situ on a mature tree of Abiesbornmulleriana. Gas-exchange responses to increasing soil drought were also studied in plants of A. bornmulleriana, A. cephalonica, and Cedrusatlantica. Stable carbon isotope composition measurements were carried out on annual growth rings of A. bornmulleriana to estimate the time-integrated values of the ratio of intercellular leaf (Ci) to ambient (Ca) CO2 concentration. Increasing ΔW around the shoots reduced A and g in such a way that either Ci remained constant or its decrease was not pronounced enough for the changes in A to be accounted for by changes in g only. This suggests a direct effect of ΔW on photosynthesis. The different Abies species showed clear differences in water-use efficiency. Abiescephalonica and A. marocana had lower water costs of CO2 assimilation (E/A) than A. nordmanniana and A. alba. It has also been shown that A. cephalonica and A. marocana are characterized by an optimal stomatal control of leaf gas exchange. Stomata closed very rapidly in A. bornmulleriana in response to water supply being withheld, even prior to there being any important decrease in leaf predawn water potential. The stomatal response in C. atlantica was more gradual. In A. bornmulleriana, drought adaptation appears to be linked to the ability to avoid internal water stress, whereas drought adaptation in C. atlantica involves the ability to tolerate internal water stress. The high stomatal sensitivity mA. bornmulleriana is also supported by the isotopic carbon composition data, as shown by the substantial interannual variations in the estimates of Ci/Ca, ranging from 0.48 for the dryest years to 0.61 for the rainy years.

Variation among wheat cultivars in the response of leaf gas exchange to light

1990 ◽  
Vol 115 (3) ◽  
pp. 305-311 ◽  
Author(s):  
A. Blum
Keyword(s):  
Gas Exchange ◽  
Photosynthetic Capacity ◽  
Leaf Gas Exchange ◽  
Genotypic Variation ◽  
Genotypic Differences ◽  
Use Efficiency ◽  
Genetic Shift ◽  
Linear Regressions ◽  
Nonlinear Fashion ◽  
High Irradiation

SUMMARYThis research was done in order to explore genetic variation in carbon exchange rate (CER) of spring wheat (Triticum aestivum) leaves in response to variable photosynthetically active radiation (PAR) and to compare old and new Israeli cultivarsin this respect. Leaf gas exchange was measured in detached turgid leaves of 17 cultivars inan open system at 25 °C when PAR was reduced from c. 1200 to 200 μmol/m2 per s. Linear regressions of CER, stomatal conductance, transpirationand leaf internal CO2 concentration (Ci) on log PAR were fitted for each leaf(regression r2 was never <0·79) and the regressions were compared among cultivars by analysis of variance.Genotypes differed significantly for the slope (b) but not the intercept (a) of the regression of CER on log PAR, indicating that genotypic differences for CER increased with increasing PAR. Photosynthetic capacity, as expressed by the ratio of CER/Ci, differed significantly among cultivars only at high PAR. Stomatal conductanceand transpiration increased in a linear or a nonlinear fashion with log PAR and differences among cultivars for both were greatest at medium to low PAR. Photosynthetic water–use efficiency (WUE) and its variation among cultivars were greatest at the highest PAR. Genotypic variation in CER athigh PAR was confirmed by repeated results for 11 cultivars intwo independent experiments.The recently developed high-yielding cultivar V652 had a higher maximum CER, higher photosynthetic capacity and greater WUE at high PAR than older and lower-yielding cultivars. The results suggest an upward genetic shift in photosynthetic capacity andin CER at high PAR when selection for yield was performed under the high-irradiation conditions of Israel.

scholarly journals Triploidy in Citrus Genotypes Improves Leaf Gas Exchange and Antioxidant Recovery From Water Deficit

2021 ◽  
Vol 11 ◽  
Author(s):  
Radia Lourkisti ◽  
Yann Froelicher ◽  
Stéphane Herbette ◽  
Raphael Morillon ◽  
Jean Giannettini ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Water Deficit ◽  
Leaf Gas Exchange ◽  
Thermal Dissipation ◽  
Oxidative Markers ◽  
Recovery Capacity ◽  
Intrinsic Water Use Efficiency ◽  
Powerful Approach ◽  
Relative Water ◽  
Use Efficiency

The triploidy has proved to be a powerful approach breeding programs, especially in Citrus since seedlessness is one of the main consumer expectations. Citrus plants face numerous abiotic stresses including water deficit, which negatively impact growth and crop yield. In this study, we evaluated the physiological and biochemical responses to water deficit and recovery capacity of new triploid hybrids, in comparison with diploid hybrids, their parents (“Fortune” mandarin and “Ellendale” tangor) and one clementine tree used as reference. The water deficit significantly decreased the relative water content (RWC) and leaf gas exchange (Pnet and gs) and it increased the levels of oxidative markers (H2O2 and MDA) and antioxidants. Compared to diploid varieties, triploid hybrids limited water loss by osmotic adjustment as reflected by higher RWC, intrinsic water use efficiency (iWUE Pnet/gs) iWUE and leaf proline levels. These had been associated with an effective thermal dissipation of excess energy (NPQ) and lower oxidative damage. Our results showed that triploidy in citrus enhances the recovery capacity after a water deficit in comparison with diploids due to better carboxylation efficiency, restored water-related parameters and efficient antioxidant system.

scholarly journals Foliar Application of Salicylic Acid Improves Water Stress Tolerance in Conocarpus erectus L. and Populus deltoides L. Saplings: Evidence from Morphological, Physiological and Biochemical Changes

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1242
Author(s):  
Zikria Zafar ◽  
Fahad Rasheed ◽  
Rana Muhammad Atif ◽  
Muhammad Asif Javed ◽  
Muhammad Maqsood ◽  
...  
Keyword(s):  
Water Stress ◽  
Stress Tolerance ◽  
Soil Water ◽  
Water Deficit ◽  
Populus Deltoides ◽  
Foliar Application ◽  
Leaf Gas Exchange ◽  
Soil Water Deficit ◽  
Water Stress Tolerance ◽  
Conocarpus Erectus

Reforestation efforts are being challenged as water stress is hampering the sapling growth and survival in arid to semiarid regions. A controlled experiment was conducted to evaluate the effect of foliar application of salicylic acid (SA) on water stress tolerance of Conocarpus erectus and Populus deltoides. Saplings were watered at 90%, 60%, and 30% of field capacity (FC), and half of the saplings under 60% and 30% FC were sprayed with 1.0 mM SA. Results indicated that dry weight production decreased significantly in Populus deltoides under both water deficit conditions, and leaf gas exchange parameters decreased significantly in both the species under both soil water deficit conditions. Foliar application of SA resulted in a significant increase in leaf gas exchange parameters, and compatible solutes, thereby increasing the dry weight production in both of the species under soil water deficit. Oxidative stress (hydrogen peroxide and superoxide anions) increased under soil water deficit and decreased after the foliar application of SA and was parallel to the increased antioxidant enzymes activity (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase). Therefore, it can be concluded that foliar application of 1.0 mM SA can significantly improve the water stress tolerance in both species, however, positive impacts of SA application were higher in Conocarpus erectus due to improved photosynthetic capacity and increased antioxidant enzyme activity.

scholarly journals Salicylic Acid-Induced Morpho-Physiological and Biochemical Changes Triggered Water Deficit Tolerance in Syzygium cumini L. Saplings

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 491
Author(s):  
Zikria Zafar ◽  
Fahad Rasheed ◽  
Rana Muhammad Atif ◽  
Muhammad Maqsood ◽  
Oliver Gailing
Keyword(s):  
Salicylic Acid ◽  
Water Stress ◽  
Gas Exchange ◽  
Soil Water ◽  
Water Deficit ◽  
Foliar Application ◽  
Leaf Gas Exchange ◽  
Dry Weight ◽  
Soil Water Deficit ◽  
Water Stress Tolerance

Fruit tree culture is at the brink of disaster in arid to semi-arid regions due to low water availability. A pot experiment was carried out to analyze whether foliar application of salicylic acid (SA) can improve water stress tolerance in Syzygiumcumini. Saplings were subjected to control (CK, 90% of field capacity, FC), medium stress (MS, 60% of FC) and high stress (HS, 30% of FC) along with foliar application of 0.5 and 1.0 mM of SA. Results showed that soil water deficit significantly decreased leaf, stem and total dry weight, leaf gas exchange attributes and chlorophyll a, b. However, root dry weight and root/shoot ratio increased under MS and HS, respectively. Contrarily, foliar application of SA significantly improved chlorophyll a, b, leaf gas exchange attributes, and dry weight production under soil water deficit. Concentration of oxidants like hydrogen peroxide and superoxide radicals, along with malondialdehyde and electrolyte leakage increased under soil water deficit; however, decreased in plants sprayed with SA due to the increase in the concentration of antioxidant enzymes like superoxide dismutase, peroxidase, catalase and ascorbate peroxidase. Results suggest that the foliar application of SA can help improve water stress tolerance in Syzygiumcumini saplings; however, validation of the results under field conditions is necessary.

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