Water potential and gas exchange did not reflect performance of Pinus radiata D. Don in an agroforestry system under conditions of soil-water deficit in a temperate environment

2005 ◽  
Vol 275 (1-2) ◽  
pp. 195-206 ◽  
Author(s):  
Isa A. M. Yunusa ◽  
Sue E. Thomson ◽  
Keith P. Pollock ◽  
Lu Youwei ◽  
Donald J. Mead
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Pinus Radiata ◽  
Agroforestry System ◽  
Soil Water Deficit ◽  
Temperate Environment

scholarly journals Water status and gas exchange of umbu plants (Spondias tuberosa Arr. Cam.) propagated by seeds and stem cuttings

2007 ◽  
Vol 29 (2) ◽  
pp. 355-358 ◽  
Author(s):  
José Moacir Pinheiro Lima Filho
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Leaf Gas Exchange ◽  
Leaf Water ◽  
Soil Water Deficit ◽  
Stem Cuttings

The experiment was carried out at the Embrapa Semi-Árido, Petrolina-PE, Brazil, in order to study the physiological responses of umbu plants propagated by seeds and by stem cuttings under water stress conditions, based on leaf water potential and gas exchange measurements. Data were collected in one-year plants established in pots containing 30 kg of a sandy soil and submitted to twenty-day progressive soil water deficit. The evaluations were based on leaf water potential and gas exchange data collection using psychrometric chambers and a portable infra-red gas analyzer, respectively. Plants propagated by seeds maintained a significantly higher water potential, stomatal conductance, transpiration and photosynthesis under decreasing soil water availability. However, plants propagated by stem cuttings were unable to maintain a favorable internal water balance, reflecting negatively on stomatal conductance and leaf gas exchange. This fact is probably because umbu plants propagated by stem cuttings are not prone to formation of root tubers which are reservoirs for water and solutes. Thus, the establishing of umbu plants propagated by stem cuttings must be avoided in areas subjected to soil water deficit.

Soybean Irrigation Initiation in Mississippi: Yield, Soil Moisture, and Economic Response

2019 ◽  
Vol 35 (1) ◽  
pp. 39-50
Author(s):  
H. C. Pringle, III ◽  
L. L. Falconer ◽  
D. K. Fisher ◽  
L. J. Krutz
Keyword(s):  
Soil Moisture ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Mississippi Delta ◽  
Soil Water Potential ◽  
Irrigation Scheduling ◽  
Silty Clay ◽  
Soil Water Deficit ◽  
Soybean Yield

Abstract. Irrigated acreage is expanding and groundwater supplies are decreasing in the Mississippi Delta. Efficient irrigation scheduling of soybean [ (L.) Merr] will aid in conservation efforts to sustain groundwater resources. The objective of this study was to develop irrigation initiation recommendations for soybean grown on Mississippi Delta soils. Field studies were conducted on a deep silty clay (SiC) in 2012, 2013, 2014, and 2015 and on a deep silty clay loam (SiCL) and deep silt loam (SiL) or loam (L) soil in 2013, 2014, and 2015. Irrigation was initiated multiple times during the growing season and soybean yield and net return were determined to evaluate the effectiveness of each initiation timing. Growth stage, soil water potential (SWP), and soil water deficit (SWD) were compared at these initiation timings to determine which parameter or combination of parameters consistently predicted the resulting greatest yields and net returns. Stress conditions that reduce yield can occur at any time from late vegetative stages to full seed on these deep soils. The wide range of trigger values found for SWP and SWD to increase yields in different years emphasizes the complexity of irrigation scheduling. Monitoring soil moisture by itself or use of a single trigger value is not sufficient to optimize irrigation scheduling to maximize soybean yield with the least amount of water every year on these soils. Monitoring one or more parameters (e.g., leaf water potential, canopy temperature, air temperature, humidity, solar radiation, and wind) is needed in conjunction with soil moisture to directly or indirectly quantify the abiotic stresses on the plant to better define when a yield reducing stress is occurring. Keywords: Irrigation initiation, Irrigation scheduling, Soil water deficit, Soil water potential, Soybean, Water conservation.

scholarly journals HydroShoot: a functional-structural plant model for simulating hydraulic structure, gas and energy exchange dynamics of complex plant canopies under water deficit - application to grapevine (Vitis vinifera L.)

2019 ◽  
Author(s):  
Rami Albasha ◽  
Christian Fournier ◽  
Christophe Pradal ◽  
Michael Chelle ◽  
Jorge Prieto ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Energy Budget ◽  
Hydraulic Structure ◽  
Scaling Up ◽  
Plant Model ◽  
Plant Canopies

This paper aims at presenting HydroShoot, a functional-structural plant model (FSPM) that is developed to simulate gas-exchange rates of complex plant canopies under water deficit conditions, by scaling up gas-exchange rates from the leaf to the canopy levels. The main hypothesis is that simulating both the hydraulic structure of the shoot together with the energy budget of individual leaves is the asset for successfully achieving this up-scaling task. HydroShoot was hence built as the ensemble of three interacting modules: hydraulic which calculates the distribution of xylem water potential across shoot hydraulic segments, energy which calculates the complete energy budget of individual leaves, and exchange which calculates net assimilation and transpiration rates of individual leaves. HydroShoot was coupled with irradiance interception and soil water balance models, and was evaluated on virtual and real grapevines having strongly contrasted canopies, under well-watered and water-deficit conditions. HydroShoot captured accurately the impact of canopy architecture and the varying soil water deficit conditions on plant-scale gas-exchange rates and leaf-scale temperature and water potential distributions. Both shoot hydraulic structure and leaf energy budget simulations were, as postulated, required to adequately scaling-up leaf to canopy gas-exchange rates. Notwithstanding, simulating the hydraulic structure of the shoot was found far more necessary to adequately performing this scaling task than simulating leaf energy balance. That is, the intra-canopy variability of leaf water potential was a better predictor of the reduction of whole plant gas-exchange rates under water deficit than the intra-canopy variability of leaf temperature. We conclude therefore that simulating the shoot hydraulic structure is a prerequisite if FSPM's are to be used to assess gas-exchange rates of complex plant canopies as those of grapevines. Finally HydroShoot is available through the OpenAlea platform (https://github.com/openalea/hydroshoot) as a set of reusable modules.

A basis for improved soil and water management for irrigated pastures in northern Victoria

1988 ◽  
Vol 28 (3) ◽  
pp. 315 ◽  
Author(s):  
SJ Blaikie ◽  
FM Martin ◽  
WK Mason ◽  
DJ Connor
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
White Clover ◽  
Soil Profile ◽  
Leaf Water ◽  
Individual Species ◽  
Soil Water Deficit ◽  
Leaf Elongation

The water relations of white clover and paspalum as monocultures and components of a mixed pasture were studied on a normal and a modified soil profile during the interval between 2 successive irrigations. Responses of individual species were similar in monocultures and mixed pastures. On the normal profile white clover was the first species to react to soil water deficit when the rate of leaf elongation fell by 33% to about 10 mm/day after 30 mm of cumulative evaporation minus rainfall (E - R). This was followed by a reduction in dawn and midday leaf water potential at around 50 mm E - R. After 65 mm E - R, leaf elongation had ceased. In contrast, paspalum showed no signs of water shortage until 70-80 mm E - R. At this stage both the rate of leaf elongation and midday leaf water potential fell. After 90 mm E - R the dawn leaf water potential fell and by 120 mm E - R leaf elongation was negligible. Modification of the profile increased soil water availability by allowing more extraction of water at depth in the profile. This delayed the onset of water stress by about 40 mm E - R in both species. These observations show that the common irrigation interval of 60-90 mm E - R in northern Victoria is likely to restrict pasture yields because it causes a period of soil water deficit stress, especially for white clover, and the development of leaf area is impeded, increasing the time taken for canopies to recover maximum productivity after grazing. To overcome these limitations farmers will have to water more frequently or modify the soil profile to provide pastures with a better water supply.

Fluxes of carbon and water in a Pinus radiata forest subject to soil water deficit

1998 ◽  
Vol 25 (5) ◽  
pp. 557 ◽  
Author(s):  
A. Arneth ◽  
F.M. Kelliher ◽  
T.M. McSeveny ◽  
J.N. Byers
Keyword(s):  
Soil Water ◽  
Water Deficit ◽  
Pinus Radiata ◽  
Growing Season ◽  
Surface Conductance ◽  
Soil Water Deficit ◽  
Soil Moisture Deficit ◽  
Abiotic Environment ◽  
Ecosystem Carbon ◽  
Moisture Deficit

We measured, by eddy covariance, seasonal CO2 (FCO2) and water (E) fluxes in an 8-year-old New Zealand Pinus radiata D.Don plantation subject to growing season soil water deficit. Average rates of FCO2 and E were highest in spring (324 mmol m-2 d-1 and 207 mol m-2 d-1, respectively) when the abiotic environment was most favourable for surface conductance and photosynthesis. During summer, fluxes were impeded by soil water (θ) deficit and were equal to or smaller than during winter (FCO2 = 46 mmol m-2 d-1 in summer and 115 mmol m-2 d-1 in winter; E = 57 and 47 mol m-2 d-1, respectively). On particularly hot and dry days, respiration exceeded photosynthetic uptake and the ecosystem was a net carbon source. Portraying the underlying biochemistry of photosynthesis, daytime half-hourly FCO2 increased with quantum irradiance absorbed by the canopy (Qabs) following a non-saturating, rectangular hyperbola. Except for winter, this relation was variable, including hysteresis attributable to diurnal variation in air saturation deficit (D). Daily ecosystem FCO2, FCO2/Qabs and FCO2/E were inversely proportional to maximum daily D, but in the cases of FCO2 and FCO2/Qabs only after soil moisture deficit became established. Consequently, as the tree growing season progressed, ecosystem carbon sequestration was strongly limited by the co-occurrence of high D at low θ.

Comparison of Stomatal Action of Orange, Soybean and Wheat Under Field Conditions

1981 ◽  
Vol 8 (1) ◽  
pp. 65 ◽  
Author(s):  
WS Meyer ◽  
GC Green
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Water Status ◽  
Radiant Energy ◽  
Plant Water ◽  
Soil Water Deficit ◽  
Late Afternoon ◽  
Constant Rate ◽  
Orange Trees

Diurnal trends in leaf diffusive conductance, Cs, leaf water potential ΨL and rates of evapotranspiration E*T were monitored on orchard-grown orange trees and field-grown crops of soybeans and wheat. Changes in these measurements were observed on soybeans and wheat as the soil water deficit increased. Maximum values of Cs of well watered plants differed between the three species (soybeans > wheat >> orange) probably as a result of different stomatal sizes and densities. Diurnal trends in Cs were common for all species, with maximum values occurring during midmorning followed by slightly lower midday values. The reduction in Cs around midday became much more pronounced as the soil water deficit increased. Slight increases in Cs values of soybeans and wheat were recorded during late afternoon. This pattern of stomatal aperture change can reasonably be explained in terms of responses to both radiant energy and plant water status. The pattern also seems to comply with the premise that stomates interact to optimize the rate of assimilation while minimizing the rate of transpiration in a given environment. Stomatal action appeared to have little effect on daily ET in soybeans under well watered conditions; ET was closely related to incoming radiant energy. The low midday values of Cs apparently caused a midday plateau in the rate of CT in wheat while even lower daytime Cs values for orange seemed to cause a low and fairly constant rate of ET which was relatively insensitive to changes in incoming radiant energy. The value of ΨL attained during mid morning at which Cs initially began to decline was fairly constant for soybeans (-0.9 to -1.1 MPa) as the predawn ΨL decreased from -0.1 to -0.8 MPa. A similar decline in predawn ΨL for wheat caused a change in the value of ΨL at which initial decreases in Cs were observed from - 1.3 MPa to -2.4 MPa. Thus there appeared to be little adjustment of stomatal action in soybeans but considerable adjustment in wheat.

scholarly journals Salicylic Acid-Induced Morpho-Physiological and Biochemical Changes Triggered Water Deficit Tolerance in Syzygium cumini L. Saplings

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 491
Author(s):  
Zikria Zafar ◽  
Fahad Rasheed ◽  
Rana Muhammad Atif ◽  
Muhammad Maqsood ◽  
Oliver Gailing
Keyword(s):  
Salicylic Acid ◽  
Water Stress ◽  
Gas Exchange ◽  
Soil Water ◽  
Water Deficit ◽  
Foliar Application ◽  
Leaf Gas Exchange ◽  
Dry Weight ◽  
Soil Water Deficit ◽  
Water Stress Tolerance

Fruit tree culture is at the brink of disaster in arid to semi-arid regions due to low water availability. A pot experiment was carried out to analyze whether foliar application of salicylic acid (SA) can improve water stress tolerance in Syzygiumcumini. Saplings were subjected to control (CK, 90% of field capacity, FC), medium stress (MS, 60% of FC) and high stress (HS, 30% of FC) along with foliar application of 0.5 and 1.0 mM of SA. Results showed that soil water deficit significantly decreased leaf, stem and total dry weight, leaf gas exchange attributes and chlorophyll a, b. However, root dry weight and root/shoot ratio increased under MS and HS, respectively. Contrarily, foliar application of SA significantly improved chlorophyll a, b, leaf gas exchange attributes, and dry weight production under soil water deficit. Concentration of oxidants like hydrogen peroxide and superoxide radicals, along with malondialdehyde and electrolyte leakage increased under soil water deficit; however, decreased in plants sprayed with SA due to the increase in the concentration of antioxidant enzymes like superoxide dismutase, peroxidase, catalase and ascorbate peroxidase. Results suggest that the foliar application of SA can help improve water stress tolerance in Syzygiumcumini saplings; however, validation of the results under field conditions is necessary.

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