scholarly journals Bark Transpiration Rates Can Reach Needle Transpiration Rates Under Dry Conditions in a Semi-arid Forest

2021 ◽  
Vol 12 ◽  
Author(s):  
Anna Lintunen ◽  
Yakir Preisler ◽  
Itay Oz ◽  
Dan Yakir ◽  
Timo Vesala ◽  
...  
Keyword(s):  
Transpiration Rate ◽  
Water Loss ◽  
Tree Mortality ◽  
Pinus Halepensis ◽  
Water Status ◽  
Stomatal Closure ◽  
Total Water ◽  
Evaporative Demand ◽  
Dry Conditions ◽  
Semi Arid

Drought can cause tree mortality through hydraulic failure and carbon starvation. To prevent excess water loss, plants typically close their stomata before massive embolism formation occurs. However, unregulated water loss through leaf cuticles and bark continues after stomatal closure. Here, we studied the diurnal and seasonal dynamics of bark transpiration and how it is affected by tree water availability. We measured continuously for six months water loss and CO2 efflux from branch segments and needle-bearing shoots in Pinus halepensis growing in a control and an irrigation plot in a semi-arid forest in Israel. Our aim was to find out how much passive bark transpiration is affected by tree water status in comparison with shoot transpiration and bark CO2 emission that involve active plant processes, and what is the role of bark transpiration in total tree water use during dry summer conditions. Maximum daily water loss rate per bark area was 0.03–0.14 mmol m−2 s−1, which was typically ~76% of the shoot transpiration rate (on leaf area basis) but could even surpass the shoot transpiration rate during the highest evaporative demand in the control plot. Irrigation did not affect bark transpiration rate. Bark transpiration was estimated to account for 64–78% of total water loss in drought-stressed trees, but only for 6–11% of the irrigated trees, due to differences in stomatal control between the treatments. Water uptake through bark was observed during most nights, but it was not high enough to replenish the lost water during the day. Unlike bark transpiration, branch CO2 efflux decreased during drought due to decreased metabolic activity. Our results demonstrate that although bark transpiration represents a small fraction of the total water loss through transpiration from foliage in non-stressed trees, it may have a large impact during drought.

scholarly journals Mutations in the tomato gibberellin receptors suppresses xylem proliferation and reduces water loss under water-deficit conditions

2020 ◽  
Author(s):  
Natanella Illouz-Eliaz ◽  
Idan Nissan ◽  
Ido Nir ◽  
Uria Ramon ◽  
Hagai Shohat ◽  
...  
Keyword(s):  
Water Deficit ◽  
Water Loss ◽  
Water Status ◽  
Stomatal Closure ◽  
Normal Growth ◽  
Hydraulic Conductance ◽  
Leaf Water Content ◽  
Whole Plant ◽  
Drought Conditions ◽  
Gibberellin Activity

AbstractLow gibberellin (GA) activity in tomato (Solanum lycopersicum) inhibits leaf expansion and reduces stomatal conductance. These lead to lower transpiration and improve water status under transient drought conditions. Tomato has three GIBBERELLIN-INSENSITIVE DWARF1 (GID1) GA receptors with overlapping activities and high redundancy. We have tested whether mutation in a single GID1 reduces transpiration without affecting growth and productivity. CRISPR-Cas9 gid1 mutants were able to maintain higher leaf water content under water-deficit conditions. Moreover, while gid1a exhibited normal growth, it showed reduced whole plant transpiration and better recovery from dehydration. Mutation in GID1a inhibited xylem vessels proliferation that led to lower hydraulic conductance. In stronger GA mutants, we also found reduced xylem vessel expansion. These results suggest that low GA activity affects transpiration by multiple mechanisms; it reduces leaf area, promotes stomatal closure and reduces xylem proliferation and expansion and as a result, xylem hydraulic conductance. We further examined if gid1a perform better than the control M82 in the field. Under these conditions, the high redundancy of GID1s was lost and gid1a plants were semi-dwarf, but their productivity was not affected. Although gid1a did not perform better under drought conditions in the field, it exhibited higher harvest index.HighlightThe loss of the tomato gibberellin receptors GID1s reduced xylem proliferation and xylem hydraulic conductance. These contribute to the effect of low gibberellin activity on water loss under water-deficit condition.

Nitrogen mitigates effect of salinity on plant water relations and photosynthesis in indian mustard ( Brassica juncea )

2008 ◽  
Vol 56 (4) ◽  
pp. 463-476
Author(s):  
N. Nathawat ◽  
M. Kuhad ◽  
A. Patel ◽  
R. Kumar ◽  
C. Goswami
Keyword(s):  
Adverse Effect ◽  
Brassica Juncea ◽  
Transpiration Rate ◽  
Saline Water ◽  
Water Status ◽  
Stomatal Closure ◽  
Substantial Reduction ◽  
Indian Mustard ◽  
Growth Stages ◽  
Osmotic Effect

The interaction between salinity (8 and 12 dS m −1 ) and three levels (40, 80 and 120 kg ha −1 ) of different forms of nitrogen (NO 3− , NH 4+ and NO 3− + NH 4+ ) were studied in Brassica juncea cv. RH-30. The plants were salinized with 8 and 12 dS m −1 at 35 and 55 days after sowing. The relative water content (RWC), water potential (Ψ w ) and osmotic potential (Ψ s ) exhibited a marked decline under salinity stress. The application of the combined form (NO 3− + NH 4+ ) of nitrogen (120 kg ha −1 ) considerably improved the water status and mitigated the adverse effect of salinity on growth. The salinity-induced osmotic effect led to stomatal closure and caused a substantial reduction in net photosynthetic rate (P N ), stomatal conductance (g s ) and transpiration rate (E) at the pre-flowering and flowering stages (45 and 65 DAS). Salinity effects were considerably moderated by additional nitrogen supply, which varied with the source of nitrogen, the level of salinity/fertilizer and the stage of plant growth. The inhibition in photosynthesis was relatively greater in ammonium-fed (NH 4+ ) than in nitrate-fed (NO 3− ) plants, while the transpiration rate was relatively lower in nitrate-fed plants grown either with or without saline water irrigation. The nitrate form of nitrogen @ 120 kg ha −1 proved best in alleviating the adverse effect of salinity on photosynthesis and transpiration at both the growth stages.

Behavioral and Physiological Resistance to Desiccation in Spotted Wing Drosophila (Diptera: Drosophilidae)

2019 ◽  
Vol 48 (4) ◽  
pp. 792-798 ◽  
Author(s):  
Philip D Fanning ◽  
Anne E Johnson ◽  
Benjamin E Luttinen ◽  
Elizabeth M Espeland ◽  
Nolan T Jahn ◽  
...  
Keyword(s):  
Water Loss ◽  
Water Status ◽  
High Surface ◽  
Volume Ratio ◽  
Spotted Wing Drosophila ◽  
Drosophila Suzukii ◽  
Geographical Regions ◽  
Wide Range ◽  
Dry Conditions ◽  
Hot Weather

Abstract With a high surface to volume ratio, small organisms must carefully regulate their internal water status. Spotted-wing drosophila, Drosophila suzukii (Matsumura), is an invasive frugivorous insect distributed across a wide range of geographical regions that can have periods of dry and hot weather, suggesting that this species has strategies to avoid stressful environments and reduce water loss. It also survives winter as an adult fly, indicating that it has adaptations to the low air humidity of this season. To determine the importance of water stress to D. suzukii, we studied their survival in environments of low humidity, which was manipulated using Drierite, and their survival and water loss in response to desiccation. Survival of both sexes was lower in drier conditions, and while female winter morph D. suzukii had higher mortality early on, remaining flies were able to survive longer in the drier conditions than the summer morphs. A bioassay method was adapted from Enjin et al. (2016) using 48-well plates to videotape the location of flies and quantify their behavioral responses to humidity. Male and female D. suzukii avoided dry conditions within the bioassay system, but only when there was at least 25% differential between humidity extremes. This response was observed for both summer and winter morphs of D. suzukii and our results provide guidance for attempts to manipulate crop environments to reduce the economic impact of this pest.

Regulation of water loss under moisture stress in sunflower genotypes: stomatal sensitivity in relation to stomatal frequency, diffusive resistances and transpiration rate, at different canopy positions

1985 ◽  
Vol 105 (3) ◽  
pp. 673-678 ◽  
Author(s):  
T. G. Prasad ◽  
V. R. Sashidhar ◽  
Malathi Chari ◽  
S. Rama Rao ◽  
R. Devendra ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Area ◽  
Seed Yield ◽  
Transpiration Rate ◽  
Water Loss ◽  
Stomatal Closure ◽  
Moisture Stress ◽  
Stress Conditions ◽  
Stomatal Frequency ◽  
Stomatal Sensitivity

SUMMARYTranspiration rate, diffusive resistances, canopy conductances and water potentials were determined at three canopy positions in non·stressed and stressed plants of sunflower hybrid BSH·1 and five other cultivars of sunflower under field conditions. The leaf area (LA) and stomatal frequency (f) was determined at the three canopy positions in field·grown plants and the total number of stomata per plant was calculated as the product of LA and f. These variables were then related to the dry·matter accumulation and seed yield in these cultivars. Cultivars with either a high leaf area or high number of stomata per plant were more productive under non-stress conditions. Under stress conditions, cultivars differed in the extent of change in conductance (g) and transpiration rate at different canopy positions. In the hybrid BSH·1, g was low at all levels in the canopy associated with a higher (less negative) water potential and this hybrid had lower transpiration rates at all canopy levels under stress although the number of stomata per plant was high. Stomatal sensitivity associated with a higher threshold water potential for stomatal closure is discussed as a possible explanation for the higher dry·matter accumulation and productivity of hybrid sunflower BSH·1 under moisture stress conditions.

scholarly journals Effects of In Vitro-formed Roots and Acclimatization on Water Status and Gas Exchange of Tissue-cultured Apple Shoots

1995 ◽  
Vol 120 (3) ◽  
pp. 435-440 ◽  
Author(s):  
Juan C. Díaz-Pérez ◽  
Kenneth A. Shackel ◽  
Ellen G. Sutter
Keyword(s):  
Steady State ◽  
Water Uptake ◽  
Water Loss ◽  
Water Status ◽  
Net Photosynthesis ◽  
Plant Water ◽  
Evaporative Demand ◽  
Higher Plant ◽  
Relative Water

Little is known about the physiological changes that occur during acclimatization and how these changes influence plant survival and growth in the new environment. In particular, it is unclear to what extent in vitro-formed roots are functional in water uptake, particularly when the plantlet is exposed to conditions of increasing evaporative demand. Tissue-cultured shoots and plantlets (shoots with roots) were acclimatized by exposing them to a linear reduction in relative humidity (RH) from 99 % to 75%over 4 days. When conductance was measured at 95% RH (21 C), in vitro shoots and plantlets showed a very high initial conductance, followed by a gradual decline, reaching steady state in 12 hours. Acclimatized shoots and plantlets had a 50% lower initial conductance compared to nonacclimatized ones, and reached steady state in 4 hours. The reduction in conductance as a result of acclimatization most likely contributes to a reduced transpiration under conditions of increased evaporative demand. Roots formed in vitro were associated with a higher plant water status, suggesting that these roots were functional in water uptake. Relative water content of the shoot was positively correlated with leaf conductance and net photosynthesis. We suggest that tissue-cultured plantlets behave as hydraulically integrated units, in which there must be a coordination between control of water loss by the shoot and uptake of water by the root to maintain a favorable plant water balance. Our results also indicate that methods that use excised shoots or leaves to determine transpiration gravimetrically may not accurately represent the stomatal water loss characteristics of tissue-cultured plants.

scholarly journals Evaluation of water loss in transit and surface runoff in a Brazilian semi-arid basin

2020 ◽  
Vol 15 (4) ◽  
pp. 1
Author(s):  
Cristian Epifanio Toledo ◽  
João Carlos Mohn Nogueira ◽  
Alexandre De Amorim Camargo
Keyword(s):  
Water Loss ◽  
Surface Runoff ◽  
High Efficiency ◽  
Heterogeneous Environments ◽  
Runoff Coefficient ◽  
Water Losses ◽  
Proposed Model ◽  
Reservoir Basin ◽  
In Transit ◽  
Semi Arid

The objective of this work was to propose and evaluate a model to estimate transit water losses and surface runoff in a Brazilian semi-arid basin, fundamental components in the hydrological studies of the region, such as in the verification of hydrological connectivity. The study area was the Orós Reservoir Basin, located in the state of Ceará. The modeling of transit water loss and surface runoff were developed based on the work of Araújo and Ribeiro (1996) and Peter et al. (2014). In the proposed model, the parameter of loss in transit (k) was estimated at 0.027 km-1 for a section of the river basin, and when simulated for other stretches it provided good flow results at the end of the stretch, obtaining an NSE of 82%. The value of the runoff coefficient was estimated at 3% and when evaluating a spatial variation of this coefficient in the basin, the values varied from 2% to 12%, and the use of specialized runoff coefficient (RC) values promoted a higher NSE in the discharge simulation in the basin. It is concluded that the proposed model to estimate transit water losses and surface runoff demonstrated a high efficiency in the simulation of hydrological processes. The basin of Orós reservoir presented a high variability of the coefficient of surface runoff, justifying the need for a greater spatiality of this coefficient in heterogeneous environments.

scholarly journals Climate Differently Impacts the Growth of Coexisting Trees and Shrubs under Semi-Arid Mediterranean Conditions

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 381
Author(s):  
J. Julio Camarero ◽  
Cristina Valeriano ◽  
Antonio Gazol ◽  
Michele Colangelo ◽  
Raúl Sánchez-Salguero
Keyword(s):  
Soil Moisture ◽  
Radial Growth ◽  
Pinus Halepensis ◽  
Growth Dynamics ◽  
Early Summer ◽  
Growth Responses ◽  
Shrub Species ◽  
High Soil Moisture ◽  
Semi Arid ◽  
Mediterranean Conditions

Background and Objectives—Coexisting tree and shrub species will have to withstand more arid conditions as temperatures keep rising in the Mediterranean Basin. However, we still lack reliable assessments on how climate and drought affect the radial growth of tree and shrub species at intra- and interannual time scales under semi-arid Mediterranean conditions. Materials and Methods—We investigated the growth responses to climate of four co-occurring gymnosperms inhabiting semi-arid Mediterranean sites in northeastern Spain: two tree species (Aleppo pine, Pinus halepensis Mill.; Spanish juniper, Juniperus thurifera L.) and two shrubs (Phoenicean juniper, Juniperus phoenicea L.; Ephedra nebrodensis Tineo ex Guss.). First, we quantified the intra-annual radial-growth rates of the four species by periodically sampling wood samples during one growing season. Second, we quantified the climate–growth relationships at an interannual scale at two sites with different soil water availability by using dendrochronology. Third, we simulated growth responses to temperature and soil moisture using the forward, process-based Vaganov‒Shashkin (VS-Lite) growth model to disentangle the main climatic drivers of growth. Results—The growth of all species peaked in spring to early summer (May–June). The pine and junipers grew after the dry summer, i.e., they showed a bimodal growth pattern. Prior wet winter conditions leading to high soil moisture before cambium reactivation in spring enhanced the growth of P. halepensis at dry sites, whereas the growth of both junipers and Ephedra depended more on high spring–summer soil moisture. The VS-Lite model identified these different influences of soil moisture on growth in tree and shrub species. Conclusions—Our approach (i) revealed contrasting growth dynamics of co-existing tree and shrub species under semi-arid Mediterranean conditions and (ii) provided novel insights on different responses as a function of growth habits in similar drought-prone regions.

Landscape-scale disturbances and regeneration in semi-arid woodlands of southwestern Australia

1994 ◽  
Vol 1 (3) ◽  
pp. 214 ◽  
Author(s):  
Colin J. Yates ◽  
Richard J. Hobbs ◽  
Richard W. Bell
Keyword(s):  
Tree Mortality ◽  
Landscape Scale ◽  
Eucalyptus Species ◽  
Natural Ecosystems ◽  
Fragmented Landscapes ◽  
The Past ◽  
Adult Tree ◽  
Western Australian ◽  
Semi Arid

Woodlands dominated by Eucalyptus salmonophloia occur both in the fragmented landscapes of the Western Australian wheatbelt and in the adjacent unfragmented goldfields area. We examined the responses of the unfragmented woodlands to landscape-scale disturbances caused by fire, floods, windstorms and drought. Sites known to have experienced disturbances of these types over the past 50 years all had cohorts of sapling-stage E. salmonophloia and other dominant Eucalyptus species. Sites disturbed either by fire, flood or storm during 1991-92 displayed adult tree mortality and extensive seedling establishment, although rates of establishment and survival varied between sites. No regeneration was observed at equivalent undisturbed sites. These results indicate that landscape-scale disturbances of several types are important drivers of the dynamics of these semi-arid woodlands. Lack of regeneration of fragmented woodlands in the wheatbelt is likely to be due to changed disturbance regimes coupled with altered physical and biotic conditions within remnants. We argue that it may be difficult to identify processes which are important for the long-term persistence of natural ecosystems in fragmented landscapes without reference to equivalent unfragmented areas.

Potential yield and water-use efficiency benefits in sorghum from limited maximum transpiration rate

2005 ◽  
Vol 32 (10) ◽  
pp. 945 ◽  
Author(s):  
Thomas R. Sinclair ◽  
Graeme L. Hammer ◽  
Erik J. van Oosterom
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Transpiration Rate ◽  
Simulation Analysis ◽  
Stomatal Closure ◽  
Risk Attitude ◽  
Potential Yield ◽  
Yield Increase ◽  
Use Efficiency ◽  
Yield Responses

Limitations on maximum transpiration rates, which are commonly observed as midday stomatal closure, have been observed even under well-watered conditions. Such limitations may be caused by restricted hydraulic conductance in the plant or by limited supply of water to the plant from uptake by the roots. This behaviour would have the consequences of limiting photosynthetic rate, increasing transpiration efficiency, and conserving soil water. A key question is whether the conservation of water will be rewarded by sustained growth during seed fill and increased grain yield. This simulation analysis was undertaken to examine consequences on sorghum yield over several years when maximum transpiration rate was imposed in a model. Yields were simulated at four locations in the sorghum-growing area of Australia for 115 seasons at each location. Mean yield was increased slightly (5–7%) by setting maximum transpiration rate at 0.4 mm h–1. However, the yield increase was mainly in the dry, low-yielding years in which growers may be more economically vulnerable. In years with yield less than ∼450 g m–2, the maximum transpiration rate trait resulted in yield increases of 9–13%. At higher yield levels, decreased yields were simulated. The yield responses to restricted maximum transpiration rate were associated with an increase in efficiency of water use. This arose because transpiration was reduced at times of the day when atmospheric demand was greatest. Depending on the risk attitude of growers, incorporation of a maximum transpiration rate trait in sorghum cultivars could be desirable to increase yields in dry years and improve water use efficiency and crop yield stability.

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