scholarly journals Nodulation Alleviates Water Stress in Vachellia Sieberiana

2021 ◽  
Author(s):  
Elizabeth Mary Telford ◽  
Nicola Stevens ◽  
Guy midgley ◽  
Caroline Lehmann
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Woody Species ◽  
Belowground Biomass ◽  
N Cycling ◽  
Life History Strategies ◽  
Nodule Biomass ◽  
Changing Patterns ◽  
Simulated Drought ◽  
Ecological Success

Abstract Species in the genus Vachellia (Fabaceae) have a global tropical and sub-tropical distribution. Numerous Vachellia species are currently observed to be expanding their indigenous ranges and increasing in dominance globally, suggesting an overarching driver. Most Vachellia species enhance nitrogen uptake mutualistically via specialized root nodule structures. Nodules contain N2-fixing rhizobia that consume host supplied carbon to catalyse atmospheric N2 into a plant useable form, a key element in plant growth. The rhizobial mutualism of some Vachellia species may be vital to understanding changing patterns of ecological success observed across the savanna precipitation gradient. Here, we investigated how the seedling root development and physiology of two dominant savanna woody species, the arid-adapted Vachellia erioloba and the mesic-adapted Vachellia sieberiana, responded to simulated drought events. Seedlings of both species were grown at 4%, 8% and 16% soil moisture content (SMC) for four months. Seedling growth and allometry of arid-adapted V. erioloba was unresponsive to water stress treatments, and no nodulation was observed, reflecting a fixed higher relative investment in belowground biomass. In contrast, V. sieberiana roots were nodulated, but developed the highest nodule biomass and growth rate when grown at the lowest soil moisture (4% SMC). These patterns suggest that effective life history strategies for the arid-30 adapted species precludes the need for rhizobial mutualism, possibly due to more “open” N cycling and lower competitive interactions in arid systems, while the more “closed” N cycling in mesic savannas, and higher competitive stress, may favour nodulation, especially under low water supply that limits root access to soil nitrogen, and signals a more competitive environment and an advantage from N2-fixing.

scholarly journals Net Photosynthesis and Growth of Three Novel Woody Species Under Water Stress: Calycanthus occidentalis, Fraxinus anomala, and Pinckneya pubens

HortScience ◽  
2007 ◽  
Vol 42 (6) ◽  
pp. 1341-1345 ◽  
Author(s):  
J. Ryan Stewart ◽  
Reid D. Landes ◽  
Andrew K. Koeser ◽  
Andrea L. Pettay
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Leaf Area ◽  
Woody Species ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
The United States ◽  
Carbon Accumulation ◽  
Organic Soils ◽  
Severe Drought

Frequent episodes of water stress in managed landscapes have led the nursery industry to look for attractive woody species that perform well under extreme conditions of drought and flooding. We chose to evaluate three taxa with highly localized natural distributions in the United States, Calycanthus occidentalis (north–central California), Fraxinus anomala (northeastern Utah), and Pinckneya pubens (northeastern Florida), each of which may merit further use under cultivated conditions beyond their respective ranges. Although widespread cultivation of each taxon may not be possible as a result of limitations related to cold hardiness, we hypothesized that each species can tolerate extremes in soil moisture availability more so than their native habitats imply. Our objective was to characterize, under greenhouse conditions, how the quantity of soil water affects gas exchange of potted plants of each species. Plants were divided into five groups, each exposed to treatment conditions ranging from complete submersion to severe drought. Complete submersion killed plants of C. occidentalis and F. anomala, although in drought or severe drought conditions, C. occidentalis plants had lower net photosynthesis and less leaf area and plant dry weight than control plants. Net photosynthesis, leaf area, and plant dry weight of partially flooded plants, however, were not found to be significantly less than that of the control plants. Mean net photosynthetic levels and plant dry weights of severe drought, drought, and control F. anomala did not differ. While severe drought plants of P. pubens exhibited much lower levels of net photosynthesis, but not plant dry weights or leaf area, than the control plants, those exposed to drought, partial flood, and complete submersion were not found to differ in net photosynthesis levels from the control plants. Due to the sustained tolerance of F. anomala and P. pubens to a range of extreme soil moisture conditions, as exhibited by net photosynthetic responses, carbon accumulation, and survival, we conclude that use of these species in landscapes is warranted if invasiveness and other potential problems are not identified. Calycanthus occidentalis, however, appears unsuitable for cultivation in areas with organic soils greater than ≈66% and lower than ≈30% soil moisture content as a result of its high mortality in flooded conditions and poor physiological responses under dry conditions.

EFFECT OF DEFICIT IRRIGATION ON YIELD, RELATIVE LEAF WATER CONTENT, LEAF PROLINE ACCUMULATION AND CHLOROPHYLL STABILITY INDEX OF COTTON–MAIZE CROPPING SEQUENCE

2013 ◽  
Vol 50 (3) ◽  
pp. 407-425 ◽  
Author(s):  
T. SAMPATHKUMAR ◽  
B. J. PANDIAN ◽  
P. JEYAKUMAR ◽  
P. MANICKASUNDARAM
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Water Content ◽  
Deficit Irrigation ◽  
Stability Index ◽  
Moisture Gradient ◽  
Proline Content ◽  
Leaf Water Content ◽  
Chlorophyll Stability Index ◽  
Soil Moisture Gradient

SUMMARYWater stress induces some physiological changes in plants and has cumulative effects on crop growth and yield. Field experiments were conducted to study the effect of deficit irrigation (DI) on yield and some physiological parameters in cotton and maize in a sequential cropping system. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through alternate deficit irrigation (ADI) practice in paired row system of drip layout that is commonly practiced in India. In the present study, PRD and DI concepts (creation of soil moisture gradient) were implemented through ADI at two levels of irrigation using drip system. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Relative leaf water content (RLWC) and chlorophyll stability index (CSI) of cotton and maize were reduced under water stress. A higher level of leaf proline content was observed under severe water-stressed treatments in cotton and maize. RLWC and CSI were highest and leaf proline content was lowest in mild water deficit (ADI at 100% crop evapotranspiration once in three days) irrigation in cotton and maize. The same treatments registered higher values for crop yields, net income and benefit cost ratio for both the crops.

Effect of Spray Components on Glyphosate Toxicity to Annual Grasses

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Douglas D. Buhler ◽  
Orvin C. Burnside
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Surfactant Concentration ◽  
Growth Stage ◽  
Annual Grass ◽  
Spray Solution ◽  
Annual Grasses ◽  
Small Grains ◽  
Carrier Volume

Field and greenhouse research was conducted during 1980 and 1981 to evaluate the effects of carrier volume, surfactant concentration, and treatment date on glyphosate [N- (phosphonomethyl)glycine] toxicity to annual-grass weeds and volunteer small grains. Glyphosate phytotoxicity increased as carrier volume was decreased from 190 to 24 L/ha. The presence of a surfactant in the spray solution did not influence grass control when glyphosate was applied in a carrier volume of 24 L/ha. When glyphosate was applied in 48 or 95 L/ha, the presence of surfactant resulted in better grass control than glyphosate without surfactant. When applied in 190 L/ha, glyphosate with 0.5% (v/v) surfactant gave better grass control than glyphosate alone or commercially formulated glyphosate. When glyphosate was applied to plants under water stress, little control was achieved regardless of plant growth stage. Glyphosate application to grass after head initiation also resulted in reduced control. Maximum weed control with glyphosate was attained when applications were made to seedlings growing actively because of adequate soil moisture and favorable temperatures.

Responses of two hybrid Populus clones to flooding, drought, and nitrogen availability. I. Morphology and growth

1992 ◽  
Vol 70 (11) ◽  
pp. 2265-2270 ◽  
Author(s):  
Zhijun Liu ◽  
Donald I. Dickmann
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Nitrogen Availability ◽  
Carbon Allocation ◽  
Hybrid Poplar ◽  
Leaf Expansion ◽  
Root Production ◽  
Leaf Initiation ◽  
Stem Biomass ◽  
Nitrogen Levels

Repeated progressive drought and flooding stress were imposed on hybrid poplar clones Populus × euramericana 'Eugenei', and Populus tristis × Populus balsamifera ‘Tristis’ grown in pots in a greenhouse under two nitrogen levels. In both clones the rate of leaf initiation was promoted only in high-N plants subjected to minimum water stress. Water stress alone did not retard the rate of leaf initiation, but it significantly reduced leaf expansion of 'Eugenei', whereas only flooding led to smaller leaves in 'Tristis'. The addition of N stimulated leaf expansion, leaf chlorophyll and N concentrations, and leaf and stem biomass production across soil moisture levels, but the greatest effect of N was associated with minimum water stress. High N altered carbon allocation towards the aboveground portions, leading to lower root to shoot ratios. High N also appeared to stimulate initiation of fine roots. Soil moisture determined the amount of biomass that accumulated in roots, with highest root production in well-watered pots and lowest in flooded pots, with the droughted treatment in between. Leaves became thinner as soil moisture decreased from flooding. Stem biomass of 'Tristis' declined more under flooding than under drought, whereas 'Eugenei' displayed a greater reduction of stem biomass in droughty than in flooded soil. Key words: water stress, nitrogen, leaf and root morphology, root to shoot ratio, biomass, Populus, flooding.

Sensitivities of isoprene emissions to soil moisture and impacts on surface ozone levels as simulated over the Euro-Mediterranean region by the regional climate model RegCM4.7chem-CLM4.5-MEGAN2.1

2021 ◽  
Author(s):  
Susanna Strada ◽  
Andrea Pozzer ◽  
Graziano Giuliani ◽  
Erika Coppola ◽  
Fabien Solmon ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Regional Climate Model ◽  
Mediterranean Region ◽  
Control Experiment ◽  
Climate Model ◽  
Surface Ozone ◽  
Regional Climate ◽  
Activity Factor ◽  
Ozone Levels

<p>In response to changes in environmental conditions (e.g., temperature, radiation, soil moisture), plants emit biogenic volatile organic compounds (BVOCs). In the large family of BVOCs, isoprene dominates and plays an important role in atmospheric chemistry. Once released in the atmosphere, isoprene influences levels of ozone, thus affecting both climate and air quality. In turn, climate change may alter isoprene emissions by increasing the occurrence and intensity of severe thermal and water stresses that alter plant functioning. To better constrain the evolution of isoprene emissions under future climates, it is critical to reduce the uncertainties in global and regional estimates of isoprene under present climate. Part of these uncertainties is related to the impact of water stress on isoprene. Recently, the BVOC emission model MEGAN has adopted a more sophisticated soil moisture activity factor γ<sub>sm</sub> which does not only account, as previously, for soil moisture available to plants but also links isoprene emissions to photosynthesis and plant water stress.</p><p>To assess the effects of soil moisture on isoprene emissions and, lastly, on ozone levels in the Euro-Mediterranean region, we use the regional climate model RegCM4.7, coupled to the land surface model CLM4.5, MEGAN2.1 and a chemistry module (RegCM4.7chem-CLM4.5-MEGAN2.1). We have performed a control experiment over 1987-2016 (with a 5-yr spin-up) at a horizontal resolution of 0.22°. Model output from the control experiment is used to initialize RegCM4.7chem-CLM4.5-MEGAN2.1 for the 10 most dry/wet summers (May-August) selected referring to the 1970-2016 precipitation climatology. Each May-August experiment is run with the old and with the new MEGAN soil moisture activity factor γ<sub>sm</sub>.  The results are then compared with a simulation whit no soil moisture activity factor. Both activity factors γ<sub>sm</sub> reduce isoprene emissions under water deficit.</p><p>During dry summers, the old soil moisture activity factor reduces isoprene emissions homogeneously over the model domain by nearly 100%, while ozone levels decrease by around 10%. When the new γ<sub>sm </sub>is used,<sub></sub>isoprene emissions are reduced with a patchy pattern by 10-20%, while ground-surface ozone levels diminish homogeneously by few percent over the southern part of the model domain.</p>

Uncovering the critical soil moisture thresholds of plant water stress for European ecosystems

2021 ◽  
Author(s):  
Zheng Fu ◽  
Philippe Ciais ◽  
David Makowski ◽  
Ana Bastos ◽  
Paul C. Stoy ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Water ◽  
Plant Water Stress

scholarly journals A conceptual dynamic vegetation-soil model for arid and semiarid zones

2008 ◽  
Vol 12 (5) ◽  
pp. 1175-1187 ◽  
Author(s):  
D. I. Quevedo ◽  
F. Francés
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Water Balance ◽  
Water Availability ◽  
Leaf Biomass ◽  
Soil Conditions ◽  
Model Parameters ◽  
Arid Zones ◽  
Soil Model ◽  
Arid And Semiarid

Abstract. Plant ecosystems in arid and semiarid climates show high complexity, since they depend on water availability to carry out their vital processes. In these climates, water stress is the main factor controlling vegetation development and its dynamic evolution. The available water-soil content results from the water balance in the system, where the key issues are the soil, the vegetation and the atmosphere. However, it is the vegetation, which modulates, to a great extent, the water fluxes and the feedback mechanisms between soil and atmosphere. Thus, soil moisture content is most relevant for plant growth maintenance and final water balance assessment. A conceptual dynamic vegetation-soil model (called HORAS) for arid and semi-arid zones has been developed. This conceptual model, based on a series of connected tanks, represents in a way suitable for a Mediterranean climate, the vegetation response to soil moisture fluctuations and the actual leaf biomass influence on soil water availability and evapotranspiration. Two tanks were considered using at each of them the water balance and the appropriate dynamic equation for all considered fluxes. The first one corresponds to the interception process, whereas the second one models the evolution of moisture by the upper soil. The model parameters were based on soil and vegetation properties, but reduced their numbers. Simulations for dominant species, Quercus coccifera L., were carried out to calibrate and validate the model. Our results show that HORAS succeeded in representing the vegetation dynamics and, on the one hand, reflects how following a fire this monoculture stabilizes after 9 years. On the other hand, the model shows the adaptation of the vegetation to the variability of climatic and soil conditions, demonstrating that in the presence or shortage of water, the vegetation regulates its leaf biomass as well as its rate of transpiration in an attempt to minimize total water stress.

scholarly journals RESEARCH NOTEA comparison between reference transpiration and measurements of evaporation for a riparian grassland site

1998 ◽  
Vol 2 (1) ◽  
pp. 129-136 ◽  
Author(s):  
J. W. Finch ◽  
R. J. Harding
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Free Water ◽  
Eddy Correlation ◽  
Meteorological Variables ◽  
Direct Measurements ◽  
Riparian Grassland ◽  
Grassland Site

Abstract. This paper compares direct measurements of evaporation with the values predicted for reference transpiration. The measurements of actual evaporation were made using an eddy correlation device on a grass field adjacent to the river Thames. Measurements of soil moisture and the driving meteorological variables were also made. The results showed that, during a period with minimal rainfall but no water stress, the cumulative values of reference transpiration compared very well with the cumulative measured evaporation and changes in soil moisture content. However, the values on specific days did not compare well. Following significant rainfall, the measured evaporation increased for a few days, probably due to evaporation of free water from the canopy or soil. Reference transpiration fell consistently below the measured evaporation once the soil moisture deficits exceeded 140 to 150 mm.

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