Changes In Stomatal Resistance Research Articles

Oxidative damage and photosynthetic impairment in tropical rice cultivars upon exposure to excess iron

Iron plays a pivotal role in the redox reactions of photosynthesis and metabolic processes such as chlorophyll synthesis. Iron availability in waterlogged soils can reach toxic levels and promote oxidative stress. Fe toxicity is the most concerning of stresses for rice in many lowland environments around the world and may cause severe impairments in rice photosynthesis. This study aimed to investigate the extension of oxidative stress after excess Fe exposure and its effects on the photosynthesis of rice cultivars with differential sensitivity. Three Brazilian rice cultivars (EPAGRI 107, BRSMG SELETA and BR IRGA 409) were grown in Hoagland nutrient solution (pH 4.0) with two Fe-EDTA doses corresponding to excess Fe (7 mM) and control (0.009 mM) treatments. After just three days of excess Fe exposure, there was a significant increase in iron concentration in the shoots. The BR IRGA 409 cultivar exhibited higher Fe accumulation in its shoots, and the EPAGRI 107 cultivar recorded the lowest values, which were below the critical toxicity level, as a resistance strategy. Impairment in light energy partitioning and oxidative damage became evident before changes in stomatal resistance, chlorophyll content, maximal PSII quantum yield or visual symptoms for the most sensitive cultivar (BR IRGA 409). The photosynthesis limitations, in addition to the impairment of excess energy dissipation in rice from iron toxicity, are the results of oxidative damage.

Trends in climatic variables and future reference evapotranspiration in Duero Valley (Spain)

Abstract. The impact of climate change and its relation with evapotranspiration was evaluated in the Duero River Basin (Spain). The study shows possible future situations 50 yr from now from the reference evapotranspiration (ETo). The maximum temperature (Tmax), minimum temperature (Tmin), dew point (Td), wind speed (U) and net radiation (Rn) trends during the 1980–2009 period were obtained and extrapolated with the FAO-56 Penman-Montheith equation to estimate ETo. Changes in stomatal resistance in response to increases in CO2 were also considered. Four scenarios were done, taking the concentration of CO2 and the period analyzed (annual or monthly) into consideration. The scenarios studied showed the changes in ETo as a consequence of the annual and monthly trends in the variables Tmax, Tmin, Td, U and Rn with current and future CO2 concentrations (372 ppm and 550 ppm). The future ETo showed increases between 118 mm (11 %) and 55 mm (5 %) with respect to the current situation of the river basin at 1042 mm. The months most affected by climate change are May, June, July, August and September, which also coincide with the maximum water needs of the basin's crops.

Responses of reference evapotranspiration to changes in atmospheric humidity and air temperature in Spain

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 44:27-40 (2010) - DOI: https://doi.org/10.3354/cr00919 Responses of reference evapotranspiration to changes in atmospheric humidity and air temperature in Spain R. Moratiel1,2,*, J. M. Durán1,2, R. L. Snyder3 1Universidad Politécnica de Madrid, Departamento de Producción Vegetal: Fitotecnia, 28040 Madrid, Spain 2CEIGRAM, Research Centre for the Management of Agricultural and Environmental Risks, 28040 Madrid, Spain 3University of California, Davis, Department of Land, Air and Water Resources, Davis, California 95616, USA *Email: ruben.moratiel@upm.es ABSTRACT: We studied the sensitivity of reference evapotranspiration (ETo) to global warming in Spain at the end of the 21st century. The FAO-56 Penman-Monteith equation was used to estimate ETo, and we examined the sensitivity of the latter to changes in temperature and relative humidity. Changes in stomatal resistance in response to increased CO2 concentration were not evaluated, nor were the changes in wind velocity and solar radiation. Different scenarios were used for estimation of future ETo in different river basins as a consequence of trends in the maximum and minimum temperatures and maximum and minimum humidities during the period 1973–2002, as observed from 38 meteorological stations. The temperature increases ranged between 0.3 and 0.7°C decade–1, and the relative humidities fluctuated between 0.1 and –3.7% decade–1. Four scenarios were simulated that considered the variations in linear tendency of the maximum and minimum temperatures and maximum and minimum relative humidities. The trends of the 4 scenarios were incorporated with the data from 338 agrometeorological stations to estimate future ETo. In all cases, there was an annual increase in ETo of 11, 21, 36 and 7% above the annual ETo (1196 mm) for Scenarios 0, 1, 2 and 3, respectively. The river basin most affected by these changes was the Ebro River valley. The most affected months were May, June, July and August, while the least affected months were November, December and January. KEY WORDS: Evapotranspiration · Climate change · Temperature · Relative humidity · Spain Full text in pdf format PreviousNextCite this article as: Moratiel R, Durán JM, Snyder RL (2010) Responses of reference evapotranspiration to changes in atmospheric humidity and air temperature in Spain. Clim Res 44:27-40. https://doi.org/10.3354/cr00919 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 44, No. 1. Online publication date: October 28, 2010 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2010 Inter-Research.

Growth and photosynthesis of pea plants under different iron supply

Soil conditions, leading to iron deficiency or toxicity, are widespread in nature. Our objective was to study the effect of Fe supply, ranging from complete deficiency to excess, on growth and on some photosynthetic indices of pea plants. Both iron deficiency and toxicity decreased shoot and root growth. Complete deficiency resulted in a lower shoot/root ratio and a higher content of dry biomass per unit of fresh biomass in roots, while iron excess led to higher content of dry biomass per unit of fresh biomass in shoot. Complete deficiency was also characterized by low chlorophyll and carotenoid content, elevated ratios of chlorophyll a/chlorophyll b and carotenoids/chlorophylls, a drop of photosynthetic rate per leaf area, and an increase of photosynthetic rate per chlorophyll. The stomatal resistance substantially increased, while the transpiration rate decreased. Smaller changes in stomatal resistance and transpiration rate, but not in photosynthetic rate per leaf area, were found under partial iron deficiency and under excess of iron. In the first case, the chlorophyll content decreased, while in the second it increased. The maximum efficiency of photosystem II was unaffected by iron supply. Even when no genetic or experimental differences existed, changes in growth, pigment content and photosynthesis due to variation of Fe supply depended on the type and severity of the imposed stress, as well as on the studied parameter. A combination of indices described better the effect of iron supply, especially when small differences were characterized.

Plant physiological and environmental controls over the exchange of acetaldehyde between forest canopies and the atmosphere

Abstract. We quantified fine scale sources and sinks of gas phase acetaldehyde in two forested ecosystems in the US. During the daytime, the upper canopy behaved as a net source while at lower heights, reduced emission rates or net uptake were observed. At night, uptake generally predominated throughout the canopies. Net ecosystem emission rates were inversely related to foliar density due to the extinction of light in the canopy and a respective decrease of the acetaldehyde compensation point. This is supported by branch level studies revealing much higher compensation points in the light than in the dark for poplar (Populus deltoides) and holly oak (Quercus ilex) implying a higher light/temperature sensitivity for acetaldehyde production relative to consumption. The view of stomata as the major pathway for acetaldehyde exchange is supported by strong linear correlations between branch transpiration rates and acetaldehyde exchange velocities for both species. In addition, natural abundance carbon isotope analysis of gas-phase acetaldehyde during poplar branch fumigation experiments revealed a significant kinetic isotope effect of 5.1±0.3‰ associated with the uptake of acetaldehyde. Similar experiments with dry dead poplar leaves showed no fractionation or uptake of acetaldehyde, confirming that this is only a property of living leaves. We suggest that acetaldehyde belongs to a potentially large list of plant metabolites where stomatal resistance can exert long term control over both emission and uptake rates due to the presence of both source(s) and sink(s) within the leaf which strongly buffer large changes in concentrations in the substomatal airspace due to changes in stomatal resistance. We conclude that the exchange of acetaldehyde between plant canopies and the atmosphere is fundamentally controlled by ambient acetaldehyde concentrations, stomatal resistance, and the compensation point which is a function of light/temperature.

Simulation of willow short‐rotation forest evaporation using a modified Shuttleworth–Wallace approach

AbstractEvaporation from a willow short‐rotation forest was analysed using a modified version of the Shuttleworth–Wallace model. The main modification consisted of a two‐layer soil module, which enabled soil surface resistance to be calculated as a function of the wetness of the top soil. Introduction of the threshold value of the leaf area index when scaling up from the leaf to the canopy resistance resulted in improvement to the simulated evaporation. The analysis was concentrated mainly on the 1988 season (May–October) when total evaporation was measured by the energy balance/Bowen ratio method throughout the growing season, covering all stages of canopy development. At the beginning of the 1994 season, soil evaporation were also measured with a ventilated chamber system. The general seasonal dynamics of the evaporation were fairly well simulated with the model. The largest deviation between measured and simulated evaporation occurred in June, when the model underestimated evaporation by about 1 mm day−1. The model underestimated also in May but not as much as in June. In September and October the performance of the model was very good. For 130 days of the period May–October the cumulated measured evaporation was 364 mm and the simulated evaporation for the same days was 362 mm. It should be pointed out that this result was obtained without calibrating the model against the measured evaporation. The total simulated evaporation for the season was 450 mm with transpiration constituting 298 mm (66%), soil evaporation 102 mm (23%) and interception evaporation 50 mm (11%). The sensitivity analysis showed, in general, that simulated evaporation was most sensitive to changes in resistances when the leaf area index was smallest, i.e. under non‐closed canopy conditions. Changes in stomatal resistance, which is one of the most sensitive parameters, with associated changes in canopy transpiration, resulted in a negative feedback effect on soil evaporation. This reduced the total evaporation's sensitivity to stomatal resistance. This type of interaction between canopy and soil or undergrowth fluxes has been observed in other studies as well. Copyright © 2001 John Wiley & Sons, Ltd.

The simulation of canopy transpiration under doubled CO 2: The evidence and impact of feedbacks on transpiration in two 1-D soil-vegetation-atmosphere-transfer models

Increasing levels of atmospheric CO 2 concentration [CO 2] has caused a debate in the scientific community over how vegetation responds to this increase — specifically in the stomatal resistance increase (SR increase) and the transpiration decrease (TR decrease). This paper presents results in changes of stomatal resistance and transpiration from two canopy model simulations under varying environmental conditions for corn and soybeans for presentday and doubled atmospheric [CO 2] conditions. The two canopy models used in the simulations were the off-line version of the land surface exchange parameterization of the GENESIS general circulation model (LSX) and the Penn State University Biosphere-Atmosphere Modeling Scheme (PSUBAMS). Simulations were performed with each model’s original stomatal resistance parameterization (SRP) and then with a field-derived SRP developed from corn and soybeans field measurements taken during 1993–1995. For corn using the original SRP, the percentage ratio (TR decrease/SR increase×100) calculated ranged from 20 to 37% for both models and values of Ω (a non-dimensional ‘decoupling coefficient’ that relates how closely the TR decrease is correlated with SR increase) ranged from 0.63 to 0.80. The results for corn, using the field derived SRP, showed that the percentage ratio and Ω ranged from 18 to 25% and 0.75 to 0.82, respectively. For soybeans, the values of the percentage ratio and Ω for the original SRP ranged from 20 to 39% and 0.61 to 0.80, respectively, while for the field derived SRP they were 12–20% and 0.80–0.87. The model derived values for the percentage ratio were substantially less than those reported in the literature for experiments conducted at the leaf scale. It is also demonstrated, using these models, how inter-canopy (LSX and PSUBAMS) and mixing layer (PSUBAMS) feedbacks modify transpiration beyond those initiated by changes in stomatal resistance alone.

Seasonal changes in water use of ash trees exposed to ozone episodes.

Young ash trees (Fraxinus excelsior L.) growing in the field were exposed to episodes of 150 nl 1-1 ozone, or to clean air, in open-top chambers at the University of Nottingham, Sucton Bonington Campus, UK, in the summer of 1992. The episodes were for 8 h daily and for 1-4 in succession, with a seasonal total of 27 d. From late-June until mid-September 1942, flow of water in the stems of individual trees was measured using a heat balance method. Short-term effects of ozone exposure on stem flow were not detected. However, in the longer-term, daily integrated stem flow values for the ozone treatment decreased throughout the measurement period relative to the clear air treatment. Further data analysis showed that integrated stem flow values for morning, evening and for the more stable central part of the day changed in a similar way, but this was statistically significant only for the evening period. No treatment differences, however, were detected in night-time water use values. This response was probably mediated by changes in stomatal resistance and, if applicable to other species, has important implications for the long-term growth of trees in regions where photochemical ozone is common.

SENSITWITY OF IRRIGATION DEMAND IN A HUMID‐TEMPERATE REGION TO HYPOTHETICAL CLIMATIC CHANGE1

ABSTRACT: An irrigation model based on a modified Thornthwaite water balance was used to simulate the effects of various hypothetical climatic changes on annual irrigation demand in a humidtemperate climate. The climatic‐change scenarios consisted of combinations of changes in temperature, precipitation, and stomatal resistance of plants to transpiration. The objectives were to (1) examine the effects of long‐term changes in these components of climatic change on annual irrigation demand, and (2) identify which of these factors would cause the largest changes in annual irrigation demand.Hypothetical climatic changes that only included increases in temperature and changes in precipitation resulted in increased annual irrigation demand, even with a 20 percent increase in precipitation. The model results showed that, for the ranges of changes in temperature and precipitation used in this study, changes in irrigation demand were more sensitive to changes in temperature than to changes in precipitation. Model results also indicated that increased stomatal resistance to transpiration counteracted the effects of increases in temperature and decreases in precipitation on irrigation demand. Changes in irrigation demand were even more sensitive to changes in stomatal resistance than to changes in temperature. A large amount of uncertainty is associated with predictions of future climatic conditions; however, uncertainty associated with natural climatic variability may be larger and may mask the effects of climatic change on irrigation demand.

Atmospheric pollution and the sensitivity of stomata on barley leaves to abscisic acid and carbon dioxide

summarySpring barley (Hordeum vulgare L. cv. Klaxon) plants were exposed to mixtures of SO2+ NO2 (at concentrations of 24–35 nl l−1of each gas, depending upon fumigation system), or to charcoal‐filtered, or unfiltered ambient air during the period in which the second, and subsequent, leaves were emerging. The ability of individual detached leaves to regulate water loss was then examined after terminating the pollutant treatment.Observations of diurnal changes in stomatal resistance of well‐watered plants, using a viscous flow porometer, failed to indicate any major alterations which could be attributed to prior exposure to SO2+ NO2. By contrast, when an ABA solution (10−1mol m−3) was applied to detached leaves, the stomata of polluted plants were less responsive than plants previously exposed to control air. The dynamics of the observed responses strongly implicated impaired physiology of the guard cells rather than mechanical changes in the epidermis that might, for example, result from damage to the cuticle. Stomatal closure was considerably slower in polluted leaves compared with the controls. This decline in responsiveness to ABA was observed using leaves excised from well‐watered plants and in the absence of any externally visible injury.The ability of stomata to respond to a range of CO2 concentrations from 195–735 μmol mol−1was also examined using individual leaves, attached to the plant, in an environmentally controlled cuvette. Here the stomata of leaves which had been fumigated with SO2+ NO2 behaved in a similar manner to the non‐fumigated leaves, both showing closure in elevated CO2 concentrations.

ABSORPTION OF NITROGEN DIOXIDE BY SUNFLOWER PLANTS GROWN AT VARIOUS LEVELS OF NITRATE

SummaryThe effect of varied levels of nitrate on the absorption of atmospheric nitrogen dioxide (NO2) by sunflower (Helianthus annus L.) plants was investigated by using a 15N dilution method. Growth of the plants was greatest at 5 mM nitrate, with less growth at 15 mM nitrate and a considerable reduction at zero nitrate. The total amount of NO2‐nitrogen absorbed by the plant depended on the plant size and total leaf area.Nitrate supply did not influence the rate of absorption of NO2 by the plants when exposed to 0.3 μl l−1 NO2. On the contrary, when the plants were exposed to 2.0 μl l−1 NO2, the absorption rate was significantly lower for the plants grown at zero nitrate compared with those grown at 5 or 15 mM nitrate. The lower rate of NO2 absorption in the nitrate‐deficient plants was not due to the changes in stomatal resistance or stomatal density of the leaves, but could have been due to an increase in mesophyll resistance resulting from accumulation of high levels of nitrite in the leaf tissues. Nitrogen dioxide at 0.3 μl l−1 exerted a nutritional effect on the nitrate‐deficient plants, while NO2 at 2.0 μl l−1 acted as a toxic air pollutant on the plants at all the levels of nitrate supplied.

CO2 EXCHANGE RATES AND STOMATAL DIFFUSIVE RESISTANCE IN SOYBEAN EXPOSED TO O3 AND SO2

Soybean (Glycine max (L.) Merr. ’Essex’) plants, 21–24 days old, were exposed to 400 μg/m3 (0.20 μL/L) ozone (O3) and 1865 μg/m3 (0.70 μL/L) sulfur dioxide (SO2) in various combinations. Fumigation was administered for 2 h either as single pollutants (O3 and SO2), simultaneously (O3 + SO2), or in overlapping pollutant combinations (O3 for 1 h followed by O3 + SO2 or SO2 for 1 h followed by SO2 + O3). Carbon dioxide exchange rates (CER) of trifoliolate leaves were measured during the fumigations, and stomatal resistance to H2O was determined immediately before and after pollutant exposure. At the end of a 2-h exposure, O3 and SO2, administered separately, did not significantly affect CER. Exposure to O3 followed by O3 + SO2, SO2 followed by SO2 + O3, and continuous O3 + SO2 significantly reduced CER to 62, 41 and 33% of preexposure rates, respectively. Stomatal resistance was not significantly altered by pollutant fumigation except in the simultaneous application of O3 + SO2 where an 11% decrease occurred. Reductions in CER in response to fumigation were not attributed to changes in stomatal resistance, but appeared to result from changes in mesophyll resistance. A proposed mechanism for pollutant-induced reduction in CER is discussed.Key words: Air pollution, net photosynthesis, pollutant mixtures

Enhancement of Ethylene Release from Leaf Tissue during Glycolate Decarboxylation

When leaf discs of Xanthium strumarium L. and Salvia splendens L. are incubated in sealed flasks in the light, more C(2)H(4) gas is released in the presence of added CO(2) (30-200 millimolar NaHCO(3)) than without CO(2). In Salvia, the maximum rate of C(2)H(4) release occurs when sufficient CO(2) (above 125 millimolar NaHCO(3)) is added to saturate photosynthesis confirming previous studies. The maximum rate of C(2)H(4) release from illuminated discs is similar to the rate in the dark with or without CO(2) in both species. Glycolate enhances a CO(2)-dependent C(2)H(4) evolution from illuminated leaf discs. However, the maximum rate of C(2)H(4) release with glycolate is the same as that observed with saturating CO(2). When photosynthesis is inhibited by darkness or by 3-(3,4-dichlorophenyl)-1,1-dimethylurea, glycolate has no effect.Studies with [2,3-(14)C]-1-aminocyclopropane-1-carboxylic acid (ACC) show that the pattern of C(2)H(4) release and the specific activity of the (14)C(2)H(4) in the presence and absence of glycolate is similar to that described above, indicating that glycolate does not alter uptake of the exogenously supplied precursor (ACC) or stimulate C(2)H(4) release from an endogenous source at appreciable rates. Glycolate oxidase in vitro generates H(2)O(2) which stimulates a slow breakdown of ACC to C(2)H(4), but since exogenous glycolate is oxidized to CO(2) in both the light and the dark it is argued that the glycolate-dependent increase in C(2)H(4) release from illuminated leaf discs is not mediated directly by the action of enzymes of glycolate catabolism. The effects of glycolate and CO(2) are not easily explained by changes in stomatal resistance. The data support the view that glycolate decarboxylation at subsaturating levels of CO(2) in the light stimulates C(2)H(4) release by raising the CO(2) level in the tissue.

Effects of position and age on leaf photosynthesis in corn (Zea mays)

The effects of position and age of leaves on CO2 exchange rate (CER) are described for a single-cross corn (Zea mays L.) hybrid ('Harrow 691') grown at 10-h and 20-h photoperiods. The effect of leaf age is also described for barren plants grown at a 10-h photoperiod.CER of newly matured leaves increased from leaf 3 to leaf 6 (10 h) or 8 (20 h). The rates were not significantly different for leaves 6 to 13, but were lower for leaf 14, at 10 h; while the rate for leaf 10 was lower than for leaf 8 but not different from that for leaves 11–15, at 20 h.CER declined with leaf age, but the rate of decline was reduced after pollination at both 10 h and 20 h. The stomatal resistance changed little for a period of 4 to 5 weeks following silking. The decline in CER of all leaves studied for barren plants was smooth, with the rate being unaffected in the postsilking period; in these plants changes in stomatal resistance closely reflected the decrease in photosynthetic rates.The results emphasize that the CER of newly matured leaves was lower for leaves produced in the early stages of ontogeny than for those maturing later, and that the pattern of decline with age in photosynthetic activity varied considerably amongst those leaves that would have been contributing assimilates to the developing ear.

Modification of chronuc sulphur dioxide injury to Lolium perennel L. By different sulphur and nitrogen nutrient treatments

The effects of high and low levels of soil N and S on chronic SO 2 injury of Lolium perenne L. cv S23 were studied in a fumigation experiment. 380 μg m −3 SO 2 depressed growth in all treatments after 62 days, without any visible symptoms on the foilage and with some indications that the high level of N decreased the severity of injury. The level of soil S had few effects on growth and there was little evidence of SO 2 acting as a nutrient in any of the treatments. Measurements of total S and N in the plants, as well as stomatal resistance and uptake rates of 35SO 2, provided no clear explanation of the effects of nutrition of the degree of injury. The results that changes in stomatal resistance reported during short-term SO 2 fumigations are only of a transitory nature and are not relevant to long-term exposures in the field, except possibly in the case of plants grown in low concentrations of both N and S.

Turbulent transfer of sulphur dioxide to a wheat crop

AbstractFluxes of sulphur dioxide to wheat were measured over two growing seasons. The deposition velocity, vg, depended primarily on affinities of surfaces for SO2 and varied from less than 0.1 to about 1.5cms−1. Stomata were an important sink, and diurnal changes in stomatal resistance accounted for most of the variation in vg when leaves were green and dry. When leaves were wet with dew, vg was generally large, irrespective of the physiological state of vegetation. A resistance analogue of transfer to the canopy agrees well with published work and is used to estimate seasonal uptake of SO2 by the crop, showing that 30% of the sulphur content of the crop at harvest was probably supplied by absorption of SO2 through stomata.

Stomatal responses to humidity in Opuntia inermis in relation to control of CO2 and H2O exchange patterns.

At constant cladode temperature the stomatal resistance of O. inermis increased when the cladode-air vapor pressure difference was increased and stomatal resistance decreased when the cladode-air vapor pressure difference was lowered. Net CO2 fixation in the dark was very responsive to these humidity dependent changes in stomatal resistance. Net CO2 fixation and stomatal resistance in the light did not respond to changes in cladode-air vapor pressure differences in the light under the conditions tested. When temperature response functions for dark CO2 fixation were examined at constant ambient humidity, the reduction in dark CO2 fixation at higher temperatures was largely due to stomatal closure in response to the increased vapor pressure difference. The water requirement for net CO2 fixation in the dark at typical nocturnal vapor pressure differences was about 10 times lower than that of net CO2 fixation in the light at vapor pressure differences typical of the late afternoon. The role of the stomatal responses to humidity in determining the patterns and rates of net CO2 exchange in the light or dark, and its possible ecological significance is discussed.

Relationship of stomatal resistance to sulfur dioxide and ozone injury in grapevines

Both SO 2 and O 3 were found to induce stomatal closure in grape leaves ( Vitis labrusca L., cv. ‘Ives’). Vines treated with 0.5 p.p.m. O 3, in the absence of SO 2, for 2 hours, had a stomatal resistance approximately 30% higher than plants treated with filtered air. Vines treated with 0.5 p.p.m. SO 2, in the absence of O 3, for 2 hours, had a stomatal resistance approximately 190% higher than plants treated with filtered air. The interaction between the 2 pollutants did not significantly alter stomatal response. In vines treated with a mixture of 0.5 p.p.m. O 3 and 0.5 p.p.m. SO 2, correlation of vine injury with changes in stomatal resistance revealed 2 separate forms of resistance to pollutant injury, a resistance to SO 2 injury correlated with stomatal closure during pollutant exposure, and a resistance to O 3 injury correlated with greater stomatal opening prior to pollutant exposure.