Water relations and growth response to drought stress of Prosopis tamarugo Phil. A review (original) (raw)
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Effects of Water Deficits on Prosopis tamarugo Growth, Water Status and Stomata Functioning
Plants
The effect of water deficit on growth, water status and stomatal functioning of Prosopis tamarugo was investigated under controlled water conditions. The study was done at the Antumapu Experiment Station of the University of Chile. Three levels of water stress were tested: (i) well-watered (WW), (ii) medium stress intensity (low-watered (LW)) and (iii) intense stress (non-watered (NW)), with 10 replicates each level. All growth parameters evaluated, such as twig growth, specific leaf area and apical dominance index, were significantly decreased under water deficit. Tamarugo twig growth decreased along with twig water potential. The stomatal conductance and CO2 assimilation decreased significantly under the water deficit condition. Tamarugo maintained a high stomatal conductance at low leaf water potential. In addition, tamarugo reduced its leaf area as a strategy to diminish the water demand. These results suggest that, despite a significant decrease in water status, tamarugo can ma...
Frontiers in Plant Science, 2018
Water extraction from the underground aquifers of the Pampa del Tamarugal (Atacama Desert, Chile) reduced the growing area of Prosopis tamarugo, a strict phreatic species endemic to northern Chile. The objective of this work was to evaluate the effect of various architectural and morpho-physiological traits adjustment of P. tamarugo subjected to three groundwater depletion intervals (GWDr): <1 m (control), 1-4 m and 6-9 m. The traits were evaluated at three levels, plant [height, trunk cross-section area, leaf fraction (fGCC), and crown size], organ [length of internodes, leaf mass per unit area (LMA), leaflet mass and area], and tissue level [wood density (WD), leaf 13 C, 18 O isotope composition (δ), and intrinsic water use efficiency (iWUE)]. In addition, soil water content (VWC) to 1.3 m soil depth, pre-dawn and midday water potential difference (), and stomatal conductance (g s) were evaluated. At the deeper GWDr, P. tamarugo experienced significant growth restriction and reduced fGCC, the remaining canopy had a significantly higher LMA associated with smaller leaflets. No differences in internode length and WD were observed. Values for δ 13 C and δ 18 O indicated that as GWDr increased, iWUE increased as a result of partial stomata closure with no significant effect on net assimilation over time. The morpho-physiological changes experienced by P. tamarugo allowed it to acclimate and survive in a condition of groundwater depletion, keeping a functional but diminished canopy. These adjustments allowed maintenance of a relatively high g s ; was not different among GWDrs despite smaller VWC at greater GWDr. Although current conservation initiatives of this species are promising, forest deterioration is expected continue as groundwater depth increases.
Adaptability of Woody Plants in Aridic Conditions
Evapotranspiration - Remote Sensing and Modeling, 2012
Ecological conditions and sources such as water, temperature, solar radiation, and carbon dioxide concentration are factors that limit plant growth, development, and reproduction. Deviations from the optimal values of these factors can cause stress. Plants are subjected to multiple abiotic and biotic stresses that adversely influence plant survival and growth by inducing physiological dysfunctions (Kozlowski & Pallardy, 2002). On the other hand, plants use different strategies for survival that are important for their distribution throughout various regions. Plants differ widely in their ability to adjust to a changing environment and the associated stress (Itail et al., 2002), including the ability to cope with drought (Kozlowski Pallardy 1997). Water deficiency is the most significant stress factor for plant growth and reproduction. Drought is mostly associated with the dieback of trees within various regions and throughout the world (Mc Dowel et al., 2008). However, physiological mechanisms of woody plant survival have not yet been described. According to Passioura (2002a), all mechanisms that support physiological functions of plants under conditions of limited water availability are mechanisms of stress resistance. These mechanisms have developed over a long period of time as part of plant adaptability. According to Jones (1993), there are three mechanisms for plant drought resistance. The first mechanism consists of avoiding water deficit and involves the limitation of transpiration and maximisation of root uptake. The second mechanism involves the tolerance to water deficit (Passioura, 2002b; Gielen et al., 2008), and the third mechanism optimises the utilisation of water (Jones 2004). Plant water stress is the result of a disproportionate balance between the amount of received and released water through various interactions with plant growth, development, and biomass production. The interactions are modified by genetic properties of the specimen and by the character and degree of plant adaptation. The amount of water that a plant can receive depends on the water supply in the soil and on eco-physiological characteristics of plant roots. The transport of water enables for a potential water gradient between the atmosphere and soil, and depends on the hydraulic resistance of the root and stem vascular system. Another component of the water regime of plants-release through transpirationis a function of the physiological availability and mobility of the water. Plant regulation of the stomata opening and transpiration depend on the pressure potential and other influencing factors. Maintenance of a positive pressure potential is therefore conditional for the survival of plants under drought. The water regime of plants is therefore an ensemble of
Further observations on the water relations ofProsopis tamarugo of the northern Atacama desert
Oecologia, 1980
Prosopis tamarugo, a tree native to the Atacama desert of Chile apparently has unique water relations. It is proposed that in its native habitat, where there is essentially no precipitation, establishment occurs during the rare flooding periods, with water coming as runoff from the Andes. These plants subsequently exist as phreatophytes tapping the relatively shallow ground water. Although phreatophytic, the plants appear to come under increasing drought stress as the growing season progresses. Because of the very low water potentials of the salty surface soils, water evidently moves from the plant into the soil under certain conditions. This water may be reabsorbed subsequently and used by the plant as the water table capillary fringe is depleted toward the end of the leafy period.
Effects of water stress and high temperature on photosynthetic rates of two species of Prosopis
Journal of Photochemistry and Photobiology B: Biology, 2008
The main aim of this research was to compare the photosynthetic responses of two species of Prosopis, Prosopis chilensis (algarrobo) and Prosopis tamarugo (tamarugo) subjected to heat and water stress, to determine how heat shock or water deficit, either individually or combined, affect the photosynthesis of these two species. The photosynthetic rates expressed as a function of photon flow density (PFD) were determined by the O 2 liberated, in seedlings of tamarugo and algarrobo subjected to two water potentials: À0.3 MPa and À2.5 MPa and to three temperatures: 25°C, 35°C and 40°C. Light response curves were constructed to obtain light compensation and light saturation points, maximum photosynthetic rates, quantum yields and dark respiration rates. The photochemical efficiency as the F v /F m ratio and the amount of RUBISCO were also determined under heat shock, water deficit, and under the combined action of both stress. Photosynthetic rates at a light intensity higher than 500 lmole photons m À2 s À1 were not significantly different (P > 0.05) between species when measured at 25°C under the same water potential. The maximum photosynthetic rates decreased with temperature in both species and with water deficit in algarrobo. At 40°C and À2.5 MPa, the photosynthetic rate of algarrobo fell to 72% of that of tamarugo. The quantum yield decreased in algarrobo with temperature and water deficit and it was reduced by 50% when the conditions were 40°C and À2.5 MPa. Dark respiration increased by 62% respect to the control at 40°C in tamarugo while remained unchanged in algarrobo. The photochemical efficiency decreased with both, high temperature and water deficit, without differences between species. RUBISCO content increased in algarrobo 35°C. Water deficit reduced the amount of RUBISCO in both species. The results of this work support the conclusion that in both Prosopis species, the interaction between high temperature and water deficit affects photosynthesis responses greater than each individual stress, and that the interactive effect is more pronounce in algarrobo than in tamarugo.
Frontiers in plant science, 2018
Water extraction from the underground aquifers of the Pampa del Tamarugal (Atacama Desert, Chile) reduced the growing area of , a strict phreatic species endemic to northern Chile. The objective of this work was to evaluate the effect of various architectural and morpho-physiological traits adjustment of subjected to three groundwater depletion intervals (GWDr): <1 m (control), 1-4 m and 6-9 m. The traits were evaluated at three levels, plant [height, trunk cross-section area, leaf fraction (GCC), and crown size], organ [length of internodes, leaf mass per unit area (LMA), leaflet mass and area], and tissue level [wood density (WD), leaf C, O isotope composition (δ), and intrinsic water use efficiency (iWUE)]. In addition, soil water content (VWC) to 1.3 m soil depth, pre-dawn and midday water potential difference (ΔΨ), and stomatal conductance (g) were evaluated. At the deeper GWDr, experienced significant growth restriction and reduced GCC, the remaining canopy had a significan...
Journal of Experimental Botany, 1998
bulk tissue elastic modulus (wall rigidity) which resulted in turgor loss at the same h in both stressed Ber (Ziziphus mauritiana Lamk.) is a major fruit tree and unstressed leaves. The possible ecological signicrop of the northwest Indian arid zone. In a study of ficance of maintenance of turgor potential and cell the physiological basis of drought tolerance in this volume at low water potentials for drought tolerance species, two glasshouse experiments were conducted in Ziziphus is discussed. in which trees were droughted during single stresscycles. In the first experiment, during a 13 d drying Key words: Ziziphus mauritiana, drought, solute accumulacycle, pre-dawn leaf water (Y leaf) and osmotic (Y p) tion, osmotic adjustment, proline. potentials in droughted trees declined from −0.5 and −1.4 MPa to −1.7 and −2.2 MPa, respectively, for a decrease in relative water content (h) of 14%. During
Water Stress in Plants: Causes, Effects and Responses
Water Stress, 2012
Plants experience water stress either when the water supply to their roots becomes limiting or when the transpiration rate becomes intense. Water stress is primarily caused by the water deficit, i.e. drought or high soil salinity. In case of high soil salinity and also in other conditions like flooding and low soil temperature, water exists in soil solution but plants cannot uptake it-a situation commonly known as 'physiological drought'. Drought occurs in many parts of the world every year, frequently experienced in the field grown plants under arid and semi-arid climates. Regions with adequate but non-uniform precipitation also experience water limiting environments. Since the dawn of agriculture, mild to severe drought has been one of the major productionlimiting factors. Consequently, the ability of plants to withstand such stress is of immense economic importance. The general effects of drought on plant growth are fairly well known. However, the primary effect of water deficit at the biochemical and molecular levels are not considerably understood yet and such understanding is crucial. All plants have tolerance to water stress, but the extent varies from species to species. Knowledge of the biochemical and molecular responses to drought is essential for a holistic perception of plant resistance mechanisms to water limited conditions in higher plants. 3. Effects of water stress on plants Drought, as an abiotic stress, is multidimensional in nature, and it affects plants at various levels of their organization. In fact, under prolonged drought, many plants will dehydrate and die. Water stress in plants reduces the plant-cell's water potential and turgor, which elevate the solutes' concentrations in the cytosol and extracellular matrices. As a result, cell enlargement decreases leading to growth inhibition and reproductive failure. This is followed by accumulation of abscisic acid (ABA) and compatible osmolytes like proline, which cause wilting. At this stage, overproduction of reactive oxygen species (ROS) and formation of radical scavenging compounds such as ascorbate and glutathione further aggravate the adverse influence. Drought not only affects plant water relations through the reduction of water content, turgor and total water, it also affects stomatal closure, limits gaseous exchange, reduces transpiration and arrests carbon assimilation (photosynthesis) rates. Negative effects on mineral nutrition (uptake and transport of nutrients) and metabolism leads to a decrease in the leaf area and alteration in assimilate partitioning among the organs. Alteration in plant cell wall elasticity and disruption of homeostasis and ion distribution in the cell has also been reported. Synthesis of new protein and mRNAs associated with the drought response is another outcome of water stress on plants. Under the water stress cell expansion slows down or ceases, and plant growth is retarded. However, water stress influences cell enlargement more than cell division. Plant growth under drought is influenced by altered photosynthesis, respiration, translocation, ion uptake, carbohydrates, nutrient metabolism, and hormones. 3.1 Photosynthesis Photosynthesis is particularly sensitive to the effects of water deficiency. Plants' resistance to water deficiency yields metabolic changes along with functional and structural rearrangements of photosynthesizing apparatus. Photosynthesis of higher plants decreases with the reduction in the relative water content (RWC) and leaf water potential. Lower