scholarly journals Growth, photosynthesis and leaf water potential in young plants of Copaifera langsdorffii Desf. (Caesalpiniaceae) under contrasting irradiances

2009 ◽  
Vol 21 (3) ◽  
pp. 197-208 ◽  
Author(s):  
Carlos Cesar Ronquim ◽  
Carlos Henrique B. A. Prado ◽  
João Paulo de Souza
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Photochemical Efficiency ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Total Biomass ◽  
Natural Conditions ◽  
Significant Difference ◽  
Copaifera Langsdorffii

Growth and leaf nutrient content were compared in young potted plants of Copaifera langsdorffii in sunny and shaded areas without water stress. Besides, carbon assimilation and leaf water relations were evaluated by net photosynthesis, potential photochemical efficiency and leaf water potential during daily courses in dry and rainy periods under natural conditions in both contrasting irradiances. Higher values of total biomass, height and leaf area occurred in sunny than in shaded area. On the other hand, all young plants survived in shade under natural water stress probably by reason of fast and intense biomass accumulation in favor of roots in early development. There was no significant difference about nutrient concentration in leaves between plants growing in sunny and shaded areas. Net photosynthesis in shade increased occasionally when bunches of direct light reached the leaves. Theses sunflecks took place more frequently and at high intensity in dry period but they were more effective for net photosynthesis in rainy period. The ability of young plants to persist under natural conditions in contrasting irradiance up to 1,230 days after sowing could explain the wide distribution of C. langsdorffii in Cerrado physiognomies and in different types of forest.

scholarly journals Drought reduced monoterpene emissions from the evergreen Mediterranean oak <i>Quercus ilex</i>: results from a throughfall displacement experiment

2009 ◽  
Vol 6 (7) ◽  
pp. 1167-1180 ◽  
Author(s):  
A.-V. Lavoir ◽  
M. Staudt ◽  
J. P. Schnitzler ◽  
D. Landais ◽  
F. Massol ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Quercus Ilex ◽  
Photochemical Efficiency ◽  
Leaf Water ◽  
Control Treatment ◽  
Summer Drought ◽  
Drought Period ◽  
Significant Difference ◽  
Monoterpene Emission

Abstract. The effects of water limitations on the emission of biogenic volatile organic compounds are not well understood. Experimental approaches studying drought effects in natural conditions are still missing. To address this question, a throughfall displacement experiment was set up in a natural forest of Quercus ilex, an evergreen Mediterranean oak emitting monoterpenes. Mature trees were exposed in 2005 and 2006 either to an additional drought, to irrigation or to natural drought (untreated control). In both years, absolute monoterpene emission rates as well as the respective standard factors of the trees exposed to normal and additional drought strongly declined during the drought periods. Monoterpene emissions were lower in year 2006 than in year 2005 (factor 2) due to a more pronounced summer drought period in this respective year. We observed a significant difference between the irrigation and additional drought or control treatment: irrigated trees emitted 82% more monoterpenes during the drought period 2006 than the trees of the other treatments. However, no significant effect on monoterpene emission was observed between normal and additional drought treatments, despite a significant effect on leaf water potential and photochemical efficiency. During the development of drought, monoterpene emissions responded exponentially rather than linearly to decreasing leaf water potential. Emissions rapidly declined when the water potential dropped below −2 MPa and photosynthesis was persistently inhibited. Monoterpene synthase activities measured in vitro showed no clear reduction during the same period. From our results we conclude that drought significantly reduces monoterpene fluxes of Mediterranean Holm oak forest into the atmosphere due to a lack of primary substrates coming from photosynthetic processes.

scholarly journals Drought reduced monoterpene emissions from <i>Quercus ilex</i> trees: results from a throughfall displacement experiment within a forest ecosystem

2009 ◽  
Vol 6 (1) ◽  
pp. 863-893 ◽  
Author(s):  
A. V. Lavoir ◽  
M. Staudt ◽  
J. P. Schnitzler ◽  
D. Landais ◽  
F. Massol ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Quercus Ilex ◽  
Photochemical Efficiency ◽  
Leaf Water ◽  
Control Treatment ◽  
Summer Drought ◽  
Drought Period ◽  
Significant Difference ◽  
Monoterpene Emission

Abstract. The effects of water limitations on the emission of biogenic volatile organic compounds are not well understood. Experimental approaches studying drought effects in natural conditions are still missing. To address this question, a throughfall displacement experiment was set up in a natural forest of Quercus ilex, an evergreen Mediterranean oak emitting monoterpenes. Mature trees were exposed in 2005 and 2006 either to an additional drought, to irrigation or to natural drought (untreated control). In both years, absolute monoterpene emission rates as well as the respective standard factors of the trees exposed to normal and additional drought strongly declined during the drought periods. Monoterpene emissions were lower in year 2006 than in year 2005 (factor 2) due to a more pronounced summer drought period in this respective year. We observed a significant difference between the irrigation and additional drought or control treatment: irrigated trees emitted 82% more monoterpenes during the drought period 2006 than the trees of the other treatments. However, no significant effect on monoterpene emission was observed between normal and additional drought treatments, despite a significant effect on leaf water potential and photochemical efficiency. During the development of drought, monoterpene emissions responded exponentially rather than linearly to decreasing leaf water potential. Emissions rapidly declined when the water potential dropped below −2 MPa and photosynthesis was persistently inhibited. Monoterpene synthase activities measured in vitro showed no clear reduction during the same period. From our results we conclude that drought significantly reduces monoterpene fluxes of Mediterranean evergreen forest into the atmosphere due to a sustained inhibition of photosynthetic carbon assimilation.

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.

Effects of water stress and soil type on photosynthesis, leaf water potential and yield of olive trees (Olea europaea L. cv. Chemlali Sfax)

2007 ◽  
Vol 47 (12) ◽  
pp. 1484 ◽  
Author(s):  
B. Ben Rouina ◽  
A. Trigui ◽  
R. d'Andria ◽  
M. Boukhris ◽  
M. Chaïeb
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Sandy Soil ◽  
Clay Soil ◽  
Sandy Loam ◽  
Leaf Water ◽  
Severe Drought ◽  
Relative Water ◽  
Olive Trees

In Tunisia, olives are grown under severe rain-fed, arid conditions. To determine the behaviour of olive trees (cv. Chemlali Sfax) during the severe drought affecting Tunisian arid areas in 2002, a range of physiological parameters were investigated in three adjacent orchards. Two olive orchards were rain-fed, one located on a sandy soil, and the other on a sandy-loam clay soil. A third orchard was also located on sandy soil, but received remedial irrigation (415 mm of water per year; ~40% of olive evapotranspiration). Predawn leaf water potential (Ψpd) did not fall below –1.52 MPa for irrigated olive trees. However, a large decrease in Ψpd was observed for rain-fed olive trees in the same period with Ψpd measured at about –3.2 MPa on sandy soil and –3.6 MPa on sandy-loam clay soil. At the same time, the minimal leaf water potential recorded at midday (Ψmin) decreased to –4.15 MPa and –4.71 MPa in the rain-fed trees for sandy and sandy-loam clay soil, respectively. For irrigated trees, the Ψmin was –1.95 MPa. These results were associated with relative water content, which varied from 80% for irrigated trees to 54 and 43.6%, respectively, for rain-fed trees and trees subjected to severe drought. In August, when the relative water content values were less than 50%, a progressive desiccation in the outer layer of canopy and death of terminal shoots were observed in trees, which grew on the sandy-loam clay soil. Furthermore, low soil water availability also affected (negatively) the net photosynthetic rate in rain-fed orchards (10.3 µmol/m2.s for irrigated trees v. 5.3 µmol/m2.s in rain-fed trees on sandy soil) and stomatal conductance (98.5 mmol/m2.s v. 69.3 mmol/m2.s). However, it improved water use efficiency (7.6 v. 4.7 µmol CO2/mmol H2O), which increased by more than 50% in both groups of rain-fed trees compared with the irrigated ones. We can conclude that olive trees respond to drought by showing significant changes in their physiological and biological mechanisms. These results also help our understanding of how olive trees cope with water stress in the field and how marginal soils can restrict growth and lower yields.

scholarly journals The importance of cuticular permeance in assessing plant water–use strategies

2020 ◽  
Vol 40 (4) ◽  
pp. 425-432
Author(s):  
Matthew Lanning ◽  
Lixin Wang ◽  
Kimberly A Novick
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Use ◽  
Leaf Water Potential ◽  
Stress Responses ◽  
Leaf Water ◽  
Plant Water ◽  
Stomatal Control ◽  
Plant Water Use ◽  
The Impact

Abstract Accurate understanding of plant responses to water stress is increasingly important for quantification of ecosystem carbon and water cycling under future climates. Plant water-use strategies can be characterized across a spectrum of water stress responses, from tight stomatal control (isohydric) to distinctly less stomatal control (anisohydric). A recent and popular classification method of plant water-use strategies utilizes the regression slope of predawn and midday leaf water potentials, σ, to reflect the coupling of soil water availability (predawn leaf water potential) and stomatal dynamics (daily decline in leaf water potential). This type of classification is important in predicting ecosystem drought response and resiliency. However, it fails to explain the relative stomatal responses to drought of Acer sacharrum and Quercus alba, improperly ranking them on the spectrum of isohydricity. We argue this inconsistency may be in part due to the cuticular conductance of different species. We used empirical and modeling evidence to show that plants with more permeable cuticles are more often classified as anisohydric; the σ values of those species were very well correlated with measured cuticular permeance. Furthermore, we found that midday leaf water potential in species with more permeable cuticles would continue to decrease as soils become drier, but not in those with less permeable cuticles. We devised a diagnostic parameter, Γ, to identify circumstances where the impact of cuticular conductance could cause species misclassification. The results suggest that cuticular conductance needs to be considered to better understand plant water-use strategies and to accurately predict forest responses to water stress under future climate scenarios.

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