RELATIVE EVAPOTRANSPIRATION IN RELATION TO SOIL WATER DEFICIT AND PREDAWN LEAF WATER POTENTIAL - APPLICATION TO TOMATO CROP -

1990 ◽  
pp. 101-112 ◽  
Author(s):  
B. Itier ◽  
N. Katerji ◽  
D. Flura ◽  
I. Ferreira
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Potential Application ◽  
Leaf Water ◽  
Soil Water Deficit ◽  
Tomato Crop ◽  
Predawn Leaf Water Potential

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.

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.

Evaporation from Lucerne Under Advective Conditions in the Sudan I. Factors Affecting Water Losses and Their Measurement

1965 ◽  
Vol 1 (1) ◽  
pp. 23-32
Author(s):  
J. P. Hudson
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Experimental Work ◽  
Leaf Water ◽  
Soil Water Deficit ◽  
Water Losses ◽  
Factors Affecting ◽  
Sudan I

SummaryIt is suggested that irrigation should ideally be based on two sets of measurements, i.e. of conditions in the leaf and of cumulative evaporation rates respectively, on the assumption that the question 'When to irrigate ? ’ can best be answered from a knowledge of leaf water potential and the daytime behaviour of stomata, and the question ‘How much water to apply?’ from a knowledge of the current soil water deficit. It is emphasized that there is no unique or fixed relation between leaf water potential and soil water deficit, and since neither can be deduced from the other it is advisable to measure both in critical experimental work on irrigation. Various methods of measuring leaf water potential and evaporation rates are discussed, and their value in experimental work assessed.

An Analysis of the Effects of Repeated Short-Term Soil Water Deficits on Stomatal Conductance to Carbon Dioxide and Leaf Photosynthesis by the Legume Macroptilium atropurpureum Cv. Siratro

1981 ◽  
Vol 8 (3) ◽  
pp. 347 ◽  
Author(s):  
MJ Fisher ◽  
DA Charles-Edwards ◽  
MM Ludlow
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Mathematical Function ◽  
Leaf Photosynthesis ◽  
Short Term ◽  
Macroptilium Atropurpureum

The response was measured of stomatal conductance and leaf photosynthesis to changing leaf water potential in the legume siratro subjected to a sequence of I-week cycles of increasing soil water deficit followed by watering. The response of stomatal conductance was described using a continuous mathematical function, which is more robust and accurate than the usual discontinuous linear function used to analyse such data. After seven successive cycles of water deficit, there was no apparent adjustment of the short-term response of leaf conductance to leaf water potential.

Photosynthesis Response of Sunlit and Shade Pepper (Capsicum annuum) Leaves at Different Positions in the Canopy Under Two Water Regimes

1994 ◽  
Vol 21 (3) ◽  
pp. 377 ◽  
Author(s):  
A Alvino ◽  
M Centritto ◽  
FD Lorenzi
Keyword(s):  
Water Potential ◽  
Capsicum Annuum ◽  
Leaf Water Potential ◽  
Co2 Exchange ◽  
Leaf Water ◽  
Predawn Leaf Water Potential ◽  
Water Regimes ◽  
Water Potentials ◽  
Sun And Shade ◽  
Shade Leaves

Pepper (Capsicum annuum L.) plants were grown in 1 m2 lysimeters under two different water regimes in order to investigate differences in the spatial arrangements of the leaves and to relate this to daily assimilation rates of leaves of the canopy. The control regime (well-watered (W) treatment) was irrigated whenever the accumulated 'A' pan evaporation reached 4 cm, whereas the water-stressed (S) treatment was watered whenever the predawn leaf water potential fell below -1 MPa. During the growing cycle, equal numbers of sun and shade leaves were chosen from the apical, middle and basal parts of the canopy, corresponding to groups of leaves of increasing age. The CO2 exchange rate (CER) was measured at 0830, 1230 and 1530 hours on 8 days along the crop cycle, on leaves in their natural inclination and orientation. Leaf water potentials were measured on apical leaves before dawn and concurrently with gas exchange measurements. Control plants maintained predawn leaf water potential at -0.3 MPa, but S plants reached values lower than -1.2 MPa. Midday leaf water potentials were about twice as low in the S plants as in the controls. Water stress reduced LA1 during the period of crop growth, and dry matter production at harvest. Stressed apical leaves appeared to reduce stress by changing their inclination. They were paraheliotropic around midday and diaheliotropic at 0830 and 1530 hours. The CER values of the S treatment were significantly lower than those of the W treatment in apical and middle leaves, whereas the CER of basal leaves did not differ in either treatments. In the S treatment, reduction in the CER values of sunlit apical leaves was more evident in the afternoon than at midday or early in the morning, whereas basal leaves were less affected by water than basal stress leaves if sunlit, and negligibly in shaded conditions.

scholarly journals Geospatial variation of grapevine water status, soil water availability, grape composition and sensory characteristics in a spatially heterogeneous premium wine grape vineyard

2014 ◽  
Vol 1 (1) ◽  
pp. 1013-1072
Author(s):  
D. R. Smart ◽  
S. Cosby Hess ◽  
R. Plant ◽  
O. Feihn ◽  
H. Heymann ◽  
...  
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Water Availability ◽  
Water Status ◽  
Leaf Water ◽  
Sensory Characteristics ◽  
Soil Water Availability ◽  
Wine Grape ◽  
Available Water

Abstract. The geoscience component of terroir in wine grape production continues to be criticized for its quasi-mystical nature, and lack of testable hypotheses. Nonetheless, recent relational investigations are emerging and most involve water availability as captured by available water capacity (AWC, texture) or plant available water (PAW) in the root zone of soil as being a key factor. The second finding emerging may be that the degree of microscale variability in PAW and other soil factors at the vineyard scale renders larger regional characterizations questionable. Cimatic variables like temperature are well mixed, and its influence on wine characteristic is fairly well established. The influence of mesogeology on mesoclimate factors has also been characterized to some extent. To test the hypothesis that vine water status mirrors soil water availability, and controls fruit sensory and chemical properties at the vineyard scale we examined such variables in a iconic, selectively harvested premium winegrape vineyard in the Napa Valley of California during 2007 and 2008 growing seasons. Geo-referenced data vines remained as individual study units throughout data gathering and analysis. Cartographic exercises using geographic information systems (GIS) were used to vizualize geospatial variation in soil and vine properties. Highly significant correlations (P < 0.01) emerged for pre-dawn leaf water potential (ΨPD), mid-day leaf water potential (ΨL) and PAW, with berry size, berry weight, pruning weights (canopy size) and soluble solids content (°Brix). Areas yielding grapes with perceived higher quality had vines with (1) lower leaf water potential (LWP) both pre-dawn and mid-day, (2) smaller berry diameter and weight, (3) lower pruning weights, and (4) higher °Brix. A trained sensory panel found grapes from the more water-stressed vines had significantly sweeter and softer pulp, absence of vegetal character, and browner and crunchier seeds. Metabolomic analysis of the grape skins showed significant differences in accumulation of amino acids and organic acids. Data vines were categorized as non-stressed (ΨPD ≥ −7.9 bars and ΨL ≥ −14.9 bars) and stressed (ΨPD ≤ −8.0 bars and ΨL ≤ −15.0 bars) and subjected to analysis of variance. Significant separation emerged for vines categorized as non-stressed versus stressed at véraison, which correlated to the areas described as producing higher and lower quality fruit. This report does not advocate the use of stress levels herein reported. The vineyard was planted to a vigorous, deep rooted rootstock (V. rupestris cv. St. George), and from years of management is known to be able to withstand stress levels of the magnitude we observed. Nonetheless, the results may suggest there is not a linear relationship between physiological water stress and grape sensory characteristics, but rather the presence of an inflection point controlling grape composition as well as physiological development.

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