共查询到20条相似文献,搜索用时 15 毫秒
1.
Almond plants (Amygdalus communis L. cv. Garrigues) were grown in the field under drip irrigated and non irrigated conditions. Leaf water potential () and leaf conductance (g1) were determined at three different times of the growing season (spring, summer and autumn). The relationships between and g1 in both treatments showed a continuous decrease of g1 as decreased in spring and summer. Data from the autumn presented a threshold value of (approx. –2.7 MPa in dry treatment, and approx. –1.4 MPa in wet treatment) below which leaf conductance remained constant. 相似文献
2.
Mature apricot (Prunus armeniaca L. cv. Búlida) trees, growing under field conditions, were submitted to two drip irrigation treatments: a control (T1), irrigated
to 100 % of seasonal crop evapotranspiration (ETc), and a continuous deficit (T2), irrigated to 50 % of the control throughout
the year. The behaviour of leaf water potential and its components, leaf conductance and net photosynthesis were studied at
three different times during the growing season, when they revealed a diurnal and seasonal pattern in response to water stress,
evaporative demand of the atmosphere and leaf age. The deficit-irrigated trees showed, among other effects, a pronounced decrease
in leaf water potential (ψw), decreased in leaf conductance (gs) and no osmotic adjustment. For this reason, gl and ψw can be considered good indicators of mature apricot tree water status and can therefore be used for irrigation scheduling. 相似文献
3.
M. C. Ruiz-Sýnchez A. Torrecillas F. Del Amor A. Leon J. M. Abrisqueta 《Biologia Plantarum》1988,30(5):327-332
Seasonal changes in leaf water potential (Φ) and leaf conductance (g1) were determined in almond trees under different irrigation regimes. The development of water stress in the rainfed treatment
induced a specific seasonal dynamics of Φ values and an important reduction in g1 values. A decrease in g1 values occurred independently of the irrigation treatment through the growing season. No statistically significant differences
were obtained in g1 values within the drip irrigated treatments. 相似文献
4.
Miconia albicans, a common evergreen cerrado species, was studied under field conditions. Leaf gas exchange and pre-dawn leaf water potential
(Ψpd) were determined during wet and dry seasons. The potential photosynthetic capacity (P
Npmax) and the apparent carboxylation efficiency (ε) dropped in the dry season to 28.0 and 0.7 %, respectively, of the maximum
values in the wet season. The relative mesophyll (Lm) and stomatal (Ls) limitations of photosynthesis increased, respectively, from 24 and 44 % in the wet season to 79 and 57 % at the peak of
the dry season when mean Ψpd reached −5.2 MPa. After first rains, the P
Npmax, ε, and Lm recovered reaching the wet season values, but Ls was maintained high (63 %). The shallow root system growing on stonemason limited by lateral concrete wall to a depth of
0.33 m explained why extreme Ψpd was brought about. Thus M. albicans is able to overcome quickly the strains imposed by severe water stress. 相似文献
5.
Keisuke Ono Atsushi Maruyama Tsuneo Kuwagata Masayoshi Mano Takahiro Takimoto Kentaro Hayashi Toshihiro Hasegawa Akira Miyata 《Global Change Biology》2013,19(7):2209-2220
Modeling stomatal behavior is critical in research on land–atmosphere interactions and climate change. The most common model uses an existing relationship between photosynthesis and stomatal conductance. However, its parameters have been determined using infrequent and leaf‐scale gas‐exchange measurements and may not be representative of the whole canopy in time and space. In this study, we used a top‐down approach based on a double‐source canopy model and eddy flux measurements throughout the growing season. Using this approach, we quantified the canopy‐scale relationship between gross photosynthesis and stomatal conductance for 3 years and their relationships with leaf nitrogen content throughout each growing season above a paddy rice canopy in Japan. The canopy‐averaged stomatal conductance (gsc) increased with increasing gross photosynthesis per unit green leaf area (Ag), as was the case with leaf‐scale measurements, and 41–90% of its variation was explained by variations in Ag adjusted to account for the leaf‐to‐air vapor‐pressure deficit and CO2 concentration using the Leuning model. The slope (m) in this model (gsc versus the adjusted Ag) was almost constant within a 15‐day period, but changed seasonally. The m values determined using an ensemble dataset for two mid‐growing‐season 15‐day periods were 30.8 (SE = 0.5), 29.9 (SE = 0.7), and 29.9 (SE = 0.6) in 2004, 2005, and 2006, respectively; the overall mid‐season value was 30.3 and did not greatly differ among the 3 years. However, m appeared to be higher during the early and late growing seasons. The ontogenic changes in leaf nitrogen content strongly affected Ag and thus gsc. In addition, we have discussed the agronomic impacts of the interactions between leaf nitrogen content and gsc. Despite limitations in the observations and modeling, our canopy‐scale results emphasize the importance of continuous, season‐long estimates of stomatal model parameters for crops using top‐down approaches. 相似文献
6.
Marco V. Gutiérrez-Soto Adriana Pacheco N. Michele Holbrook 《Trees - Structure and Function》2008,22(3):393-401
We used experimental defoliations to examine the effect of leaf age on the timing of leaf shedding in two tropical dry forest
trees. Trees of the deciduous Bombacopsis quinata (bombacaceae, a.k.a. Pachira quinata) and the brevi-deciduous Astronium graveolens (anacardiaceae) were manually defoliated for three times during the rainy season. All trees started to produce a new crown
of leaves 2 weeks after defoliation, and continued expanding leaves throughout the rainy season. At the transition to the
dry season, the experimental groups consisted of trees with known differences in maximum leaf age. Defoliations resulted in
declines in stem growth but did not affect the mineral content or water relations of the leaves subsequently produced. There
was no effect of leaf age on the timing of leaf abscission in B. quinata. In A. graveolens, the initiation of leaf shedding followed in rank order, the maximum leaf age of the four treatments, but there was substantial
coherence among treatments in the major period of leaf abscission such that trees completed leaf shedding at the same time.
In the two species, leaf water potential (ΨL) and stomatal conducantce (g
S) declined with the onset of the dry season, reaching minimum values of –0.9 MPa in P. quinata and <–2.0 MPa in A. graveolens. Within each species, leaves of different age exhibited similar ΨL and g
S at the onset of drought, and then decreased at a similar rate as the dry season progressed. Overall, our study suggests that
the environmental factors were more important than leaf age in controlling the timing of leaf shedding. 相似文献
7.
Sandra J. Bucci Guillermo Goldstein Frederick C. Meinzer Augusto C. Franco Paula Campanello Fabián G. Scholz 《Trees - Structure and Function》2005,19(3):296-304
Seasonal regulation of leaf water potential (L) was studied in eight dominant woody savanna species growing in Brazilian savanna (Cerrado) sites that experience a 5-month dry season. Despite marked seasonal variation in precipitation and air saturation deficit (D), seasonal differences in midday minimum L were small in all of the study species. Water use and water status were regulated by a combination of plant physiological and architectural traits. Despite a nearly 3-fold increase in mean D between the wet and dry season, a sharp decline in stomatal conductance with increasing D constrained seasonal variation in minimum L by limiting transpiration per unit leaf area (E). The leaf surface area per unit of sapwood area (LA/SA), a plant architectural index of potential constraints on water supply in relation to transpirational demand, was about 1.5–8 times greater in the wet season compared to the dry season for most of the species. The changes in LA/SA from the wet to the dry season resulted from a reduction in total leaf surface area per plant, which maintained or increased total leaf-specific hydraulic conductance (Gt) during the dry season. The isohydric behavior of Cerrado tree species with respect to minimum L throughout the year thus was the result of strong stomatal control of evaporative losses, a decrease in total leaf surface area per tree during the dry season, an increase in total leaf-specific hydraulic conductance, and a tight coordination between gas and liquid phase conductance. In contrast with the seasonal isohydric behavior of minimum L, predawn L in all species was substantially lower during the dry season compared to the wet season. During the dry season, predawn L was more negative than bulk soil estimated by extrapolating plots of E versus L to E=0. Predawn disequilibrium between plant and soil was attributable largely to nocturnal transpiration, which ranged from 15 to 22% of the daily total. High nocturnal water loss may also have prevented internal water storage compartments from being completely refilled at night before the onset of transpiration early in the day. 相似文献
8.
Roupala montana is an evergreen species widespread in the seasonal savannas of the central plains of Brazil. I examined the degree of coupling of photosynthetic gas-exchange characteristics, water relations and growth responses of R. montana with regard to seasonal changes in soil water availability. Despite a rainless period of over three months soil water potential at 60 cm depth reached values of only about -1.0 MPa, while pre-dawn leaf water potential (l) reached about -0.4 MPa by the end of the three-month drought. Thus, R. montana had access to deep soil water in the dry period, but pre-dawn l did not reach the high wet season values of -0.2 MPa. Most of the shoot growth was concluded in the onset of the rainy season. Although some individual branches might have shown some extension thereafter, most of them remained inactive during the rest of the rainy season and the subsequent dry season. New leaf production was also restricted to the first part of the wet period. R. montana remained evergreen in the dry season, but there was a 27% decrease in the number of leaves and herbivory removed about 16% of the leaf area still present in the plant. CO2-exchange rates of these leaves reached only ca. 55% of the maximum rainy season values of 14 µmol m-2 s-1. Thus, the estimated potential daily carbon gain was about 34% of the maximum by the end of the dry period. These values will be even lower, if we considered the decrease in photosynthetic rates that occurred around midday. These reductions in photosynthetic rates as a result of partial stomatal closure were measured both in the wet and dry season and they were related to increases in the evaporative demand of the atmosphere. In conclusion, the combined effect of herbivory, leaf loss and reductions in photosynthetic rates limited plant productivity in the dry season. 相似文献
9.
Stomatal control of water use in olive tree leaves 总被引:2,自引:1,他引:1
Little is known about the strategies used by olive trees to overcome the long dry periods typical of the areas where they are cropped. This makes it difficult to optimize the water supply in orchards. To study the control of water consumption by olive trees, measurements of leaf water potential () and stomatal conductance to H2O (g) were made on 26-year-old t Manzanillo olive trees under three irrigation treatments. The first treatment provided enough water to cover the crop water demand, the next treatment supplied one third of that rate, and the final treatment was no irrigation at all, typical of dry-farming conditions. Under conditions of high vapour pressure deficit of the air (Da), the olive trees prevented excessive water loss by closing their stomata. Leaves of the current year showed better stomatal control than did the 1-year-old leaves. The upper-bound functional relationships between t g and t Da and photon flux density (IP) were obtained by boundary-line analysis, based on a technique of non-linear least squares. Maximum values of t g were observed at relatively low levels of t IP, from about 500 mol m-2 s-1, and a proportional decrease in t g with increasing t Da was also found, at least for values of up to approximately 3.5 kPa. Higher values of t g were observed in the morning than in the afternoon, for similar levels of t IP and t Da. Unirrigated olive trees recovered quickly after the dry season, showing values of and t g similar to those of irrigated trees after just two days. 相似文献
10.
Relationships Between Climatic Variables and Sap Flow, Stem Water Potential and Maximum Daily Trunk Shrinkage in Lemon Trees 总被引:3,自引:0,他引:3
M. F. Ortuño Y. García-Orellana W. Conejero M. C. Ruiz-Sánchez O. Mounzer J. J. Alarcón A. Torrecillas 《Plant and Soil》2006,279(1-2):229-242
The feasibility of obtaining sap flow (SF), maximum daily trunk shrinkage (MDS) and midday stem water potential (Ψstem) baselines or reference values for use in irrigation scheduling was studied in adult Fino lemon trees (Citrus limon (L.) Burm. fil.) grafted on sour orange (C. aurantium L.) rootstocks. Plants were irrigated daily above their water requirements in order to obtain non-limiting soil water conditions.
The results indicated that baselines for plant-based water status indicators (MDS, SF and Ψstem) can be obtained, even though there was a certain scattering of the data points representing the relations between the plant-based
measurements and the environmental variables (reference evapotranspiration, solar radiation, vapour pressure deficit and temperature).
SF was more closely associated with changes in the studied evaporative demand variables than were MDS and Ψstem. SF and Ψstem were more closely correlated with changes in reference evapotranspiration (ETo) (r
2 = 0.93 and 0.79, respectively), while MDS behaviour was best correlated with mean daily air temperature (T
m) (r
2 = 0.76). Increases in the evaporative demand induced more negative Ψstem values and, as a consequence, SF increased, which, in turn, was translated into an increase in MDS. This confirmed that SF
and MDS were very good predictors of the plant water status during the observation period and their continuous recording offers
the promising possibility of their use in automatic irrigation scheduling in lemon trees. 相似文献
11.
Physiological responses to water stress following a conditioning period in berseem clover 总被引:4,自引:0,他引:4
Berseem clover (Trifolium alexandrinum L.) is an important crop in semi-arid regions; its herbage and seed yields are often reduced by water stress. Our objectives
were (i) to determine the effect of water stress, applied after a conditioning period, on water relations, proline accumulation
and plant dry weight, and (ii) to investigate if some physiological responses differed in varieties of berseem. Five cultivars
(Axi, Bigbee, Lilibeo, Sacromonte and Saniros) were grown in a controlled environment, and subjected to four irrigation treatments
(T1, T2, T3 and T4 referring to plants irrigated to field capacity every 1, 2, 3 or 4 d, respectively) during a conditioning
period (12 d). T1 treatment indicated the well-watered control, whereas T2, T3 and T4 treatments represented the conditioned
plants. Leaf water potential (Ψ), osmotic potential (Ψπ), relative water content (RWC), gravimetric soil water content (GSWC)
and leaf proline concentration were recorded during the conditioning period and a subsequent water deficit period (3 d) applied
at early flowering growth stage. The conditioned plants subjected to subsequent water deficit maintained higher values of
Ψ, Ψπ, RWC and GSWC, and lower values of leaf proline concentration. Reductions in parameter values were inversely related
to the water stress severity that plants had previously experienced. At the end of the experiment, T1 showed 42%, 58% and
31% lower values for Ψ, Ψπ and RWC, respectively, than those of T4. Conditioned plants were also shorter and accumulated less
leaf, stem and total dry weight. The conditioning treatments did not affect the relation between Ψ and Ψπ since conditioned
plants show similar values of Ψπ as the control at the same Ψ value. Thus, drought acclimation in berseem clover contributed
to water stress tolerance by the maintenance of tissue hydration. The berseem cultivars examined showed differences in plant
growth parameters, but they were very similar for physiological responses to water deficit. The main genetic difference was
recorded for turgor maintenance capacity.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
Roberto Tognetti Riccardo d’Andria Giovanni Morelli Arturo Alvino 《Plant and Soil》2005,273(1-2):139-155
A field experiment on olive trees (Olea europaea L.) was designed with the objective to search for an optimum irrigation scheduling by analyzing the possible effects of deficit irrigation. Treatments were: a non-irrigated control (rainfed) and three treatments that received seasonal water amount equivalent to 33 and 66% of crop evapotranspiration (ETC) in the period August–September (respectively 33II and 66II), and 66% of (ETC) from late May to early October (66I-II). Atmospheric evaporative demand and soil moisture conditions were regularly monitored. Irrigation effects on plant water relations were characterized throughout a growing season. Whole-plant water use, in deficit irrigated (66I-II) and rainfed olive trees, was determined using a xylem sap flow method (compensation heat-pulse technique). The magnitude of variations in water use and the seasonal dynamic of water relations varied among treatments, suggesting that olive trees were strongly responsive to both irrigation amount and time. Physiological parameters responded to variations in tree water status, soil moisture conditions and atmospheric evaporative demand. All measurements of tree water status were highly correlated with one another. There was a considerable degree of agreement between daily transpiration deduced from heat-pulse velocity and that determined by calibration using the water balance technique. Deficit irrigation during the whole summer (66I-II) resulted in improved plant water relations with respect to other watering regimes; while, severe regulated deficit irrigation differentiated only slightly 33II treatment from rainfed plants. Nevertheless, regulated deficit irrigation of olive trees after pit hardening (66II) could be recommended, at least in soil, cultivar and environmental conditions of this study. 相似文献
13.
Potted two-year-old lemon plants (Citrus limon (L.) Burm. fil.) cv. Fino, growing under field conditions were subjected to
drought by withholding irrigation for 13 d. After that, plants were re-irrigated and the recovery was studied for 5 d. Control
plants were daily irrigated maintaining the soil matric potential at about -30 kPa. Young leaves of control plants presented
higher leaf conductance (g1) and lower midday leaf water potential (Ψmd) than mature ones. Young leaves also showed higher
leaf water potential at the turgor loss point (Ψtlp) than mature leaves. In both leaf types g1 decreased with increased vapour
pressure deficit of the atmosphere. From day 1 of the withholding water, predawn and midday leaf water potentials (Ψpd and
Ψmd) decreased, reaching in both cases minimum values of -5.5 MPa, with no significant differences between mature and young
leaves. Water stress induced stomatal closure, leaf rolling and partial defoliation. No osmotic adjustment was found in response
to water stress in either leaf type, but both were able to enhance the cell wall elasticity (elastic adjustment). After rewatering,
leaf water potential recovered quickly (within 2 d) but g1 did not.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
We assessed the daily time‐courses of CO2 assimilation rate (A), leaf transpiration rate (E), stomatal conductance for water vapour (gs), leaf water potential ( Ψ w) and tree transpiration in a wet and a dry season for three late‐stage canopy rainforest tree species in French Guiana differing in leaf carbon isotope composition ( δ 13C). The lower sunlit leaf δ 13C values found in Virola surinamensis ( ? 29·9‰) and in Diplotropis purpurea ( ? 30·9‰), two light‐demanding species, as compared to Eperua falcata ( ? 28·6‰), a shade‐semi‐tolerant species, were clearly associated with higher maximum gs values of sunlit leaves in the two former species. These two species were also characterized by a high sensitivity of gs, sap flow density (Ju) and canopy conductance (gc) to seasonal soil drought, allowing maintenance of high midday Ψ w values in the dry season. The data for Diplotropis provided an original picture of increasing midday Ψ w with increasing soil drought. In Virola, stomata were extremely sensitive to seasonal soil drought, leading to a dramatic decrease in leaf and tree transpiration in the dry season, whereas midday Ψ w remained close to ? 0·3 MPa. The mechanisms underlying such an extremely high sensitivity of stomata to soil drought remain unknown. In Eperua, gs of sunlit leaves was non‐responsive to seasonal drought, whereas Ju and gc were lower in the dry season. This suggests a higher stomatal sensitivity to seasonal drought in shaded leaves than in sunlit ones in this species. 相似文献
15.
Abstract Climatic conditions should not hinder nutrient release from decomposing leaf‐litter (mineralization) in the humid tropics, even though many tropical forests experience drought lasting from several weeks to months. We used a dry‐season irrigation experiment to examine the effect of seasonal drought on nutrient concentrations in leaf‐fall and in decomposing leaf‐litter. In the experiment, soil in two 2.25‐ha plots of old‐growth lowland moist forest on Barro Colorado Island, Republic of Panama, was watered to maintain soil water potential at or above field capacity throughout the 4‐month dry season. Wet‐season leaf‐fall had greater concentrations of nitrogen (N, 13.5 mg g?1) and calcium (Ca, 15.6 mg g?1) and lower concentrations of sulfur (S, 2.51 mg g?1) and potassium (K, 3.03 mg g?1) than dry‐season leaf‐fall (N = 11.6 mg g?1, Ca = 13.6 mg g?1, S = 2.98 mg g?1, K = 5.70 mg g?1). Irrigation did not affect nutrient concentrations or nutrient return from forest trees to the forest floor annually (N = 18 g m?2, phosphorus (P) = 1.06 g m?2, S = 3.5 g m?2, Ca = 18.9 g m?2, magnesium = 6.5 g m?2, K = 5.7 g m?2). Nutrient mineralization rates were much greater during the wet season than the dry season, except for K, which did not vary seasonally. Nutrient residence times in forest‐floor material were longer in control plots than in irrigated plots, with values approximately equal to that for organic matter (210 in control plots vs 160 in irrigated plots). Calcium had the longest residence time. Forest‐floor material collected at the transition between seasons and incubated with or without leaching in the laboratory did not display large pulses in nutrient availability. Rather, microorganisms immobilized nutrients primarily during the wet season, unlike observations in tropical forests with longer dry seasons. Large amounts of P moved among different pools in forest‐floor material, apparently mediated by microorganisms. Arylsulfatase and phosphatase enzymes, which mineralize organically bound nutrients, had high activity throughout the dry season. Low soil moisture levels do not hinder nutrient cycling in this moist lowland forest. 相似文献
16.
Xylem cavitation and hydraulic control of stomatal conductance in Laurel (Laurus nobilis L.) 总被引:15,自引:4,他引:11
Sebastiano Salleo rea Nardini Franco Pitt & Maria A. Lo Gullo 《Plant, cell & environment》2000,23(1):71-79
The possible link between stomatal conductance (gL), leaf water potential ( Ψ L) and xylem cavitation was studied in leaves and shoots of detached branches as well as of whole plants of Laurus nobilis L. (Laurel). Shoot cavitation induced complete stomatal closure in air‐dehydrated detached branches in less than 10 min. By contrast, a fine regulation of gL in whole plants was the consequence of Ψ L reaching the cavitation threshold ( Ψ CAV) for shoots. A pulse of xylem cavitation in the shoots was paralleled by a decrease in gL of about 50%, while Ψ L stabilized at values preventing further xylem cavitation. In these experiments, no root signals were likely to be sent to the leaves from the roots in response to soil dryness because branches were either detached or whole plants were growing in constantly wet soil. The stomatal response to increasing evaporative demand appeared therefore to be the result of hydraulic signals generated during shoot cavitation. A negative feedback link is proposed between gL and Ψ CAV rather than with Ψ L itself. 相似文献
17.
Significance and limits in the use of predawn leaf water potential for tree irrigation 总被引:5,自引:1,他引:4
Améglio Thierry Archer Philippe Cohen Moisés Valancogne Charles Daudet François-alain Dayau Sylvia Cruiziat Pierre 《Plant and Soil》1999,207(2):155-167
Research in estimating the water status of crops is increasingly based on plant responses to water stress. Several indicators
can now be used to estimate this response, the most widely available of which is leaf water potential (ΨLWP) as measured with a pressure chamber. For many annual crops, the predawn leaf water potential (ΨPLWP), assumed to represent the mean soil water potential next to the roots, is closely correlated to the relative transpiration
rate, RT. A similar correlation also holds for young fruit trees grown in containers. However, exceptions to this rule are
common when soil water content is markedly heterogeneous.
Two experimental conditions were chosen to assess the validity of this correlation for heterogeneous soil water content: 1)
young walnut trees in split-root containers. The heterogeneity was created by two unequal compartments (20% and 80% of total
volume), of which only the smaller was irrigated and kept at a moisture content higher than field capacity (permanent drainage).
2) adult walnut trees in an orchard. In this case, soil water heterogeneity was achieved by limiting the amount of localised
irrigation (20% of the irrigated control)
which was applied every evening.
Values of sap flux and of minimum and predawn leaf water potentials with homogeneous and heterogeneous soil water content
were compared for trees grown in the orchard and in containers. In spite of intense drought reflected by very low RT or stem
water potential, ΨPLWP of trees under heterogeneous moisture conditions remained high (between -0.2 and -0.4 MPa) both in the orchard and in containers.
These values were higher than those usually considered critical under homogeneous soil conditions. A semi-quantitative model,
based on the application of Ohm's analogy to split-root conditions, is proposed to explain the apparently conflicting results
in the literature on the relation between ΨPLWP and soil water potential.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
Lemon plants (Citrus limonum L. cv. Verna) were grown in the field under two different flood irrigation treatments. The dry treatment received four irrigations
per year (March, July, September and November) and the wet treatment one monthly. The amounts of water applied per year for
dry and wet treatments were 340.0 mm and 1020.0 mm, respectively. The effects of the two treatments on certain aspects of
the plant water relations during the period between flowering and the end of rapid fruit growth (critical period) were studied.
Soil matric potential (ψm) and leaf water potential (ψi) values in the dry treatment revealed development of water stress
during the experimental period. The water supply in the wet treatment seems sufficient to achieve the crop water requirements.
The g1 values in July were higher in the wet than dry treatments. Pronounced oscillations in g1 from sunrise to afternoon were found especially in the dry treatment. 相似文献
19.
A. L. García L. Marcelis F. Garcia-Sanchez N. Nicolas V. Martínez 《Biologia Plantarum》2007,51(4):707-712
The responses of water relations, stomatal conductance (gs) and growth parameters of tomato (Lycopersicon esculentum Mill. cv. Royesta) plants to nitrogen fertilisation and drought were studied. The plants were subjected to a long-term, moderate
and progressive water stress by adding 80 % of the water evapotranspirated by the plant the preceding day. Well-watered plants
received 100 % of the water evapotranspirated. Two weeks before starting the drought period, the plants were fertilised with
Hoagland’s solution with 14, 60 and 110 mM NO3
− (N14, N60 and N110, respectively). Plants of the N110 treatment had the highest leaf area. However, gs was higher for N60 plants and lower for N110 plants. At the end of the drought period, N60 plants showed the lowest values
of water potential (Ψw) and osmotic potential (Ψs), and the highest values of pressure potential (Ψp). N60 plants showed the highest Ψs at maximum Ψp and the highest bulk modulus of elasticity. 相似文献
20.
On the dependence of salt tolerance of beans (Phaseolus vulgaris L.) on soil water matric potentials
Summary Bean plants (Kora cv) were grown in potted soil artificially salinized by adding NaCl and CaCl2 to the irrigation water to obtain an electrical conductivity of the soil saturation extract (ECe) thirty days after emergence of 0.1, 0.3, 0.5 and 0.7 S/m at 25°C and a sodium adsorption ratio (SAR) of 4 (mmol/l)2. Thereafter, plants were irrigated when soil water matric potential (M) was in the range of –20 to –30 kPa (wet treatment) and when M was in the range of –40 to –60 kPa (dry treatment).Transpiration rates (Tr) and leaf extension rates (LER) per plant or per unit of leaf area were decreased by increasing soil salinity and by decreasing soil moisture. However, a given decrement of M produced a considerable larger decrement in Tr of LER than an equivalent decrement of soil water osmotic potential (0). Absolute yields of green pods under wet treatments were from twice to one and a half time as large under the wet than under the dry treatment at equivalent values of 0. Relative yields were reduced by 25% when ECe were about 0.5 S/m and 0.7 S/m in the dry and wet treatment respectively. Salt tolerance data of crops may not have a quantitative interest when soil irrigation regimes under which they were obtained are not specified. 相似文献