Water relations of woody plants on contrasting soils during drought: does edaphic compensation account for dry rainforest distribution?

2009 ◽  
Vol 57 (8) ◽  
pp. 629 ◽  
Author(s):  
Timothy J. Curran ◽  
Peter J. Clarke ◽  
Nigel W. M. Warwick
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Soil Type ◽  
Plant Traits ◽  
Sandy Soils ◽  
Soil Types ◽  
Severe Drought ◽  
Ecotypic Differentiation ◽  
Compensation Hypothesis

The occurrence of dry rainforest in climates considered drier than the recognised limit for rainforest has been explained by the edaphic compensation hypothesis, which proposed that finer-textured soils facilitate the occurrence of rainforest at climatic extremes. We tested this by examining the effect of soil type on the water relations and plant traits of four dry rainforest species, during a severe drought and subsequent non-drought periods. We predicted plants growing in sandy soils would exhibit higher levels of water stress (lower predawn water potential and stomatal conductance) and possess morphological and physiological traits that more typically reflect drought resistance (late leaf fall in deciduous species, low specific leaf area, vertical leaf angles and stomata that close at low water potential) than those growing in loam soils. During drought, levels of water stress were similar across soil types, while post-drought plants on sandy soils were less stressed. Soil type did not cause shifts in drought tolerance traits, suggesting there has been no ecotypic differentiation of dry rainforest species across soil types for these traits. Hence, we found no support for the edaphic compensation hypothesis in adult plants; future studies should consider other life-cycle stages, such as seedlings.

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.

Anatomical adaptations of the desert species Stipa lagascae against drought stress

Biologia ◽  
2015 ◽  
Vol 70 (8) ◽  
Author(s):  
Façal Boughalleb ◽  
Raoudha Abdellaoui ◽  
Zied Hadded ◽  
Mohammed Neffati
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Deficit ◽  
Cortical Cell ◽  
Severe Drought ◽  
Leaf Rolling ◽  
Drought Period ◽  
Severe Water Deficit ◽  
Anatomical Adaptations ◽  
Stipa Lagascae

AbstractStipa lagascae R. & Sch. (perennial bunchgrass) is one of the most promising steppic species for arid and desert lands of Tunisia. The present study was designed to study the effect of drought on root and leaf anatomy, water relationship, and the growth of three- month-old S. lagascae plants, submitted to water deficit (5, 10, 15, 20, 30 days of withheld irrigation) and grown in pots in greenhouse conditions. The results show that water deficit treatments reduced the biomass accumulation (MS) and leaf water potential (Ψw) of plants. However, leaf relative water content (RWC) decreased significantly only at severe drought. The root’s anatomical features showed reduced root cross-sectional diameter under water deficit. Conversely, epidermis was unaffected by water stress. Moderate and/or severe water deficit (20-30 days) reduced significantly the cortex thickness, cortical cell size, stele diameter, xylem vessel diameter and the stele/root crosssectional ratio, while the number of cortical cells increased for severe water deficit. The cuticles and mesophyll of S. lagascae was thickened by moderate to severe drought and the entire lamina thickness was increased significantly by 5.8% only after 30 days of water deficit while epidermis was unaffected by water deficit. However, severe water deficit (30 days) decreased the width and the length of the bundle sheath. At the same time, the mesophyll cells size and both the xylem and phloem vessels diameter diminished by 12, 16.8 and 17.5%, respectively. Leaf rolling occurs as a response to water deficit and its level increases as the drought period is progressing in plants while reduced bulliform cells size occurred only at severe water deficit. Our findings suggest a complex network of root and leaf anatomical adaptations such as a reduced vessel size with lesser cortical and mesophyll parenchyma formation and increased leaf rolling. These proprieties are required for the maintenance of water potential and energy storage under water stress which can improve the resistance of S. lagascae to survive in extremely arid areas

Efficiency of the salt flotation technique in the recovery of Ascaris lumbricoides eggs from the soil

1995 ◽  
Vol 69 (1) ◽  
pp. 1-5 ◽  
Author(s):  
M.O. Ajala ◽  
S.O. Asaolu
Keyword(s):  
Specific Gravity ◽  
Sandy Soil ◽  
Sodium Nitrate ◽  
Ascaris Lumbricoides ◽  
Soil Type ◽  
Zinc Sulphate ◽  
Sandy Soils ◽  
Soil Types ◽  
Flotation Technique ◽  
Zinc Sulphate Solution

AbstractThe efficacy of the salt flotation technique using saturated solutions of sodium nitrate (specific gravity 1.30) and zinc sulphate (specific gravity 1.16) for separating Ascaris lumbricoides eggs from clay, loamy and sandy soils has been investigated. Ten samples of each of the egg concentrations of 100, 500, 2500, 5000 and 10,000 eggs/25 g of soil were used for each soil type. Using T-test and ANOVA, the number of eggs recovered from sand was significantly higher than from loam and the number from loam significantly higher than from clay. With sodium nitrate, the maximum egg recovery rate was 25.04% from sandy soil at a concentration of 500 eggs/25 g soil while with zinc sulphate it was 13.88% also from sandy soil and concentration of 500 eggs/25 g soil. While the number of eggs recovered increased with soil egg concentration, the percentage of eggs recovered is inversely proportional to egg concentration. The number of eggs recovered with sodium nitrate was significantly higher than with zinc sulphate solution in the three soil types.

Water stress and reduced fruit size in micro-irrigated pear trees under deficit partial rootzone drying

2007 ◽  
Vol 58 (7) ◽  
pp. 670 ◽  
Author(s):  
Mark G. O'Connell ◽  
Ian Goodwin
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Fruit Size ◽  
Leaf Conductance ◽  
Stem Water Potential ◽  
Crop Water ◽  
Reproductive Growth ◽  
Stem Water ◽  
Partial Rootzone Drying

Crop water relations, vegetative and reproductive growth, and soil water status were studied during 2 seasons to determine the effectiveness of partial rootzone drying (PRD) in a mature micro-irrigated pear orchard in the Goulburn Valley, Australia. PRD treatments were 50% (PRD50) and 100% (PRD100) of predicted crop water requirement (ETc) applied on one side of the tree alternated on a 14-day cycle compared with a Control treatment, which received 100% of ETc irrigated on both sides of the tree. Irrigation was applied daily by micro-jets to replace ETc estimated using reference crop evapotranspiration (ETo) and a FAO-56 crop coefficient of 1.15 adjusted for tree size. The PRD50 regime applied 174–250 mm for the season v. 347–470 mm for both the Control and PRD100 treatments. Irrigation maintained a well watered rootzone under the emitter compared with the drying profiles of the alternated wet/dry irrigated zones of the PRD treatments. There was no significant benefit of PRD100 compared with the Control irrigation regime. Similar vegetative growth (canopy radiation interception), reproductive growth (fruit growth rate, final fruit size, yield), fruit quality (total soluble solids, flesh firmness), and crop water relations (midday leaf conductance, midday leaf and stem water potential) were measured between the Control and PRD100. Trees under the PRD50 regime showed symptoms of severe water stress, that being greater fruit drop, reduced fruit size, lower yield, reduced leaf conductance, and lower leaf and stem water potential. The 50% water saving afforded by PRD50 led to a yield penalty of 16–28% compared with the Control and PRD100. PRD50 fruit failed to meet commercial cannery requirements due to poor fruit size. We conclude from an agronomic basis that deficit PRD irrigation management is not recommended for micro-irrigated pear orchards on fine-textured soils in the Goulburn Valley, Australia.

scholarly journals Canopy temperature and heat stress are increased by compound high air temperature and water stress and reduced by irrigation – a modeling analysis

2021 ◽  
Vol 25 (3) ◽  
pp. 1411-1423 ◽  
Author(s):  
Xiangyu Luan ◽  
Giulia Vico
Keyword(s):  
Heat Stress ◽  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Air Temperature ◽  
Water Availability ◽  
Plant Traits ◽  
Soil Water Potential ◽  
Canopy Temperature ◽  
Threshold Temperature

Abstract. Crop yield is reduced by heat and water stress and even more when these conditions co-occur. Yet, compound effects of air temperature and water availability on crop heat stress are poorly quantified. Existing crop models, by relying at least partially on empirical functions, cannot account for the feedbacks of plant traits and response to heat and water stress on canopy temperature. We developed a fully mechanistic model, coupling crop energy and water balances, to determine canopy temperature as a function of plant traits, stochastic environmental conditions, and irrigation applications. While general, the model was parameterized for wheat. Canopy temperature largely followed air temperature under well-watered conditions. But, when soil water potential was more negative than −0.14 MPa, further reductions in soil water availability led to a rapid rise in canopy temperature – up to 10 ∘C warmer than air at soil water potential of −0.62 MPa. More intermittent precipitation led to higher canopy temperatures and longer periods of potentially damaging crop canopy temperatures. Irrigation applications aimed at keeping crops under well-watered conditions could reduce canopy temperature but in most cases were unable to maintain it below the threshold temperature for potential heat damage; the benefits of irrigation in terms of reduction of canopy temperature decreased as average air temperature increased. Hence, irrigation is only a partial solution to adapt to warmer and drier climates.

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.

Comparing plant water relations for wheat with alternative pulse and oilseed crops grown in the semiarid Canadian prairie

2009 ◽  
Vol 89 (5) ◽  
pp. 823-835 ◽  
Author(s):  
H W Cutforth ◽  
S V Angadi ◽  
B G McConkey ◽  
M H Entz ◽  
D Ulrich ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Oilseed Crops ◽  
Pulse Crops ◽  
The Mean

Understanding the drought physiology of alternate crops is essential to assess the production risks of new cropping systems. We compared the water relations of dry (field) pea (Pisum sativum L.), chickpea (Cicer arietinum L.), canola (Brassica napus L.) and mustard (Brassica juncea L.) with spring wheat (Triticum aestivum L.) under different moisture availabilities in field trials conducted in 1997 and 1998 at Swift Current, SK. Stress experience and stress responses varied with crop type. In general, there were similarities in drought physiology between the two pulse crops and between the two oilseed crops. The mean predawn leaf water potential of pea was frequently lowest, while the mean midday leaf water potential of wheat was at least -0.40 MPa lower than for any other crop. The crops exhibited different strategies to overcome water stress. Wheat had the lowest osmotic potential at full turgor, except under drought when turgor was lowest for chickpea and wheat; the highest values were observed in Brassica spp. Mean midday pressure potentials were lowest in wheat (and mostly negative, indicating loss of turgor) and highest for the pulse crops. Mean midday pressure potential for canola was positive when well-watered, otherwise it was near 0. Despite lowering osmotic potential, wheat could not maintain positive turgor much of the time at midday. Pulse crops, with the contributions from both osmotic adjustment and cell elasticity, maintained positive turgor over a wider range of water potentials compared with the other crops. With regard to both osmotic adjustment and tissue elasticity, we ranked the crops from high to low ability to adjust to moderate to severe water stress as pulses > wheat > Brassica oilseeds. Key words: Leaf water, osmotic, turgor potentials, wheat, pulse, canola, semiarid prairie

scholarly journals Canopy temperature and heat stress are increased by compound high air temperature and water stress, and reduced by irrigation – A modeling analysis

2020 ◽  
Author(s):  
Xiangyu Luan ◽  
Giulia Vico
Keyword(s):  
Heat Stress ◽  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Air Temperature ◽  
Water Availability ◽  
Plant Traits ◽  
Soil Water Potential ◽  
Canopy Temperature ◽  
Threshold Temperature

Abstract. Crop yield is reduced by heat and water stress, and even more when they co-occur. Yet, compound effects of air temperature and water availability on crop heat stress are poorly quantified: crop models, by relying at least partially on empirical functions, cannot account for the feedbacks of plant traits and response to heat and water stress on canopy temperature. We developed a fully mechanistic model coupling crop energy and water balances, to determine canopy temperature as a function of plant traits, stochastic environmental conditions and their variability; and irrigation applications. While general, the model was parameterized for wheat. Canopy temperature largely followed air temperature under well-watered conditions; but when soil water potential was more negative than −0.14 MPa, further reductions in soil water availability led to a rapid rise in canopy temperature – up to 10 °C warmer than air at soil water potential of −0.62 MPa. More intermittent precipitation led to higher canopy temperatures and longer periods of potentially damaging crop canopy temperatures. Irrigation applications aimed at keeping crops under well-watered conditions could reduce canopy temperature, but in most cases were unable to maintain it below the threshold temperature for potential heat damage; the benefits of irrigation became smaller as average air temperature increased. Hence, irrigation is only a partial solution to adapt to warmer and drier climates.

Time Trends for Change in Osmotic Adjustment and Water Relations of Leaves of Cenchrus ciliaris During and After Water Stress

1983 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Leaf Growth ◽  
Weight Ratio ◽  
Bound Water ◽  
Arid Environment ◽  
Leaf Water ◽  
Buffel Grass

Buffel grass was subjected to a soil drying cycle for 5 weeks in a semi-arid environment. As water stress developed, the leaf water relations characteristics of these plants (Dry treatment) were compared with those of irrigated plants (Wet treatment). Leaf water potential (Ψ) of the Dry treatment measured at 1400 h decreased to a minimum of -6.9 MPa. The stressed leaves adjusted osmotically, with the osmotic potential at full turgor (Ψπ100) decreasing (becoming more negative) linearly with time (0.017 MPa day-1) and with decreasing water potential measured at 1400 h (0.11 MPa per 1 MPa decrease in Ψ). Maximum osmotic adjustment (Ψπ100 Wet -Ψπ100 Dry) was 0.66 MPa, and this change together with lower cell wall elasticity decreased by 1.03 MPa the water potential (Ψ0) at which the stressed leaves lost turgor. Differences between the stress- acclimated Dry leaves and the Wet leaves in bound water, turgid weight:dry weight ratio and the relative water content at which they reached zero turgor were small and inconsistent. At 18 days after rewatering, the Ψπ100 value of acclimated leaves was still 0.18 MPa lower than that of the control leaves. The substantial shift in Ψ0 gained the stress-acclimated leaves only one extra day before they lost turgor at 1400 h, and only 2.5 extra days before being permanently wilted. This small gain in time and the rapid cessation of leaf growth even before positive turgor was completely lost suggests that osmotic adjustment may not contribute greatly to continued leaf growth in water-stressed plants of buffel grass.

scholarly journals Water Relations of Fruit End Cracking in French Prune (Prunus domestica L. cv. French)

1992 ◽  
Vol 117 (5) ◽  
pp. 824-828 ◽  
Author(s):  
Rémy E. Milad ◽  
Kenneth A. Shackel
Keyword(s):  
Mechanical Properties ◽  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Osmotic Potential ◽  
Vertical Axis ◽  
Field Conditions ◽  
Prunus Domestica ◽  
Irrigation Regimes

Irrigation of previously water-stressed French prune trees is known to induce fruit end cracking. The relationships between end cracking, water relations, and mechanical properties of the skin of French prune were studied as a function of irrigation regimes under field conditions. Water stress resulted in the accumulation of solutes in the fruit of nonirrigated trees. A gradient in osmotic potential (ΨS) existed along the vertical axis of fruit from all treatments; ΨS was always lower at the stylar than stem end. Irrigation of previously water-stressed trees (irrigated-dry treatment) resulted in ΨS gradients exceeding those of all other treatments. Moreover, estimated turgor (ΨP) at the stylar end of the fruit increased 2-fold within 24 hours after irrigation. These changes were accompanied by the onset of fruit end cracking, and neither the well-watered controls nor the continuously droughted fruit exhibited such changes. During the 24 hours following irrigation, the overall ΨS of irrigated-dry treatment fruit was diluted by the same amount as the calculated increase in fruit volume. However, during the same period, ΨS at the stem end of the fruit showed more dilution than expected, and ΨS at the stylar end of the fruit concentrated, indicating a redistribution of solutes. There were no differences in skin mechanical properties along the fruit vertical axis and, hence, this could not have accounted for the observed changes in ΨS and ΨP. Thus, when previously stressed French prune trees were irrigated, the overall recovery in water potential (Ψ) and the subsequent movement of solutes to the stylar end of the fruit resulted in apparently excessive turgors in this region and hence the observed pattern of end cracking.

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