Transpiration

The use of the compensation heat-pulse velocity (CHPV) technique to estimate sap flow in olive trees as a means of irrigation scheduling can be a difficult task because of the naturally heterogeneity of hydraulic functioning of sapwood area in this species. As a result, the monitoring of an unreasonably large number of both trees and CHPV gauges per tree is needed for accurate estimation of orchard transpiration. The approach used in this paper restricts the monitoring of a large number of both trees and gauges to a very short time (a day) and allows the long term estimation of transpiration of several olive trees by the continuous monitoring of a sole CHPV gauge installed in a single tree. In an experimental olive orchard in southern Italy, we monitored six CHPV gauges in three well irrigated trees (treatment T100) and six CHPV gauges in three rain-fed trees (treatment T0) at half hour intervals for 60 days during summer 1999. For each i th gauge at each day, we linearly regressed the sap flow (Q i , l h (1 ) against the mean sap flow of the all other n(/1 gauges of the same treatment (Qm i ). The regression parameters were used to obtain an estimation of Qm i (EQm i ) throughout the trial using the data of any single i th gauge. In order to test the prediction power of the model of i th gauge, the estimated mean sap flow (EQm i ) values were regressed day by day against the actually measured Qm i . The same procedure was also applied at the time scale of a day, that is to the daily cumulative value of Q i and Qm i . In all cases, we obtained high statistical significance of the models applied to data as confirmed by the high adjusted R 2 estimates. Our analyses show the feasibility of estimating the transpiration rate of many trees by monitoring sap flow in a single tree by the use of a sole CHPV gauge. The results of this work indicate that CHPV can be a useful and powerful method for irrigation scheduling for olive and other tree species. #

Examination by scanning electron microscopy showed abaxial stomata on in vitro cultured apple (Malus pumila Mill.) leaves. With leaf ontogeny, most of these stomata appeared to lose their regulatory ability while developing wide vestibules of up to 20 #m in diameter. It is proposed that these deformed stomata may be a possible cause for the excessive transpirational water loss and consequent dehydration associated with transferring plants regenerated in vitro from culture.

Soilless plant growth systems are widely used as a means to save irrigation water and to reduce groundwater contamination. While nutrient concentrations in the growth medium are depleted due to uptake by the plants, salinity and toxic substances accumulate due to transpiration. A theoretical model is suggested, to simulate nutrient uptake by plants grown in soilless cultures with recycled solutions. The model accounts for salinity accumulation with time and plant growth, and its effects on uptake of the different nutrients by means of interaction with Na and Cl ions. The sink term occurs due to uptake by a growing root system. Influx as a function of the ion concentration is according to Michaelis-Menten active mechanisms for K + , NO 3 − -N, NH 4 + -N, PO 4 -P, Ca 2+ , Mg 2+ and SO 4 2− , whose influx parameters are affected by Na and Cl − , but not with time (age). Sodium influx is passive above a critical concentration. Sum of cations-anions concentrations is balanced by Cl − to maintain electro-neutrality of the growth solution. Salinity (by means of Na concentration) suppresses root and leaf growth, which further effect uptake and transpiration. The model accounts for instantaneous transpiration losses, during daytime only and its effect on uptake of nutrients and plant development due to salt accumulation. The model was tested against NO 3 − and K + uptake by plants associated with cumulative transpiration and with different NaCl salinity levels. Deviations from observed K + uptake should be attributed to the salinity tolerance of the plants. In a study with data obtained from published literature, the model indicated that nutrient depletion and salinity buildup might be completely different with fully grown-up plants (that do not grow) and plants that grow with time. Depletion of different nutrients are according to their initial concentration and plant uptake rate, but also affected by their interactions with Na and Cl ions.

Polyaromatic hydrocarbons (PAHs) are major and recalcitrant pollutants of the environment and their removal presents a significant problem. Phytoremediation has shown much promise in PAH removal from contaminated soil, but may be inhibited because the plant experiences phytotoxic effects from low-molecular-weight PAHs such as naphthalene. This paper describes the construction of a naphthalene-degrading endophytic strain designated Pseudomonas putida VM1441(pNAH7). This strain was found to be an efficient colonizer of plants, colonizing both the rhizosphere and interior root tissues. The inoculation of plants with P. putida VM1441(pNAH7) resulted in the protection of the host plant from the phytotoxic effects of naphthalene. When inoculated plants were exposed to naphthalene, both seed germination and plant transpiration rates were higher than those of the uninoculated controls. The inoculation of plants with this strain also facilitated higher (40%) naphthalene degradation rates compared with uninoculated plants in artificially contaminated soil.

A ®ve-layered water balance model, with water movement between layers along hydraulic gradients, was developed and parameterized for a eucalypt plantation (Eucalyptus grandis Hill ex. Maiden hybrids) in Brazil. Available soil water controls stomatal conductance and hence transpiration, which is calculated by the Penman±Monteith equation. The model accounts for changes in the depths of the water table. Calculations are supported by measurements: the test period was from October 1995 to September 1996 in a 9-year-old plantation in an experimental catchment in eastern Brazil. Total transpiration for the year was 1116 mm, with 151 mm intercepted and re-evaporated and another 78 mm soil surface evaporation, giving evapotranspiration of 1345 mm compared to rainfall of 1396 mm. The water balance was closed by net¯ow below the root zone of about 25 mm and an increase in water storage (in the ®rst layer) of 24 mm. The model also estimated a transpiration de®cit (difference between the potential and current transpiration) of 125 mm for the period. Upward¯ux from the water table was around 82 mm and piezometric measurements showed 2.5 m recession of the water table for the same period. The upward¯ux into the root zone was about 1 mm day 21 at the end of a long dry season; that kept the water storage in that zone to about 15% of capacity and helped prevent complete stomatal closure.

Th e fi rst crop chosen to parameterize and test the new FAO AquaCrop model is maize (Zea mays L.). Working mainly with data sets from 6 yr of maize fi eld experiments at Davis, CA, plus another 4 yr of Davis maize canopy data, a set of conservative (nearly constant) parameters of AquaCrop, presumably applicable to widely diff erent conditions and not specifi c to a given crop cultivar, was evaluated by test simulations, and used to simulate the 6 yr of Davis data. Th e treatment variable was irrigation-withholding water aft er planting continuously, only up to tasseling, from tasseling onward, or intermittently, and with full irrigation (FI) as the control. From year to year, plant density (7-11.9 plants m −2 ), planting date (14 May-15 June), cultivar (a total of four), and atmospheric evaporative demand varied. Th e conservative parameters included: canopy growth and canopy decline coeffi cient (CDC); crop coeffi cient for transpiration (Tr) at full canopy; normalized water productivity for biomass (WP*); soil water depletion thresholds for the inhibition leaf growth and of stomatal conductance, and for the acceleration of canopy senescence; reference harvest index (HI o ); and coeffi cients for adjusting harvest index (HI) in relation to inhibition of leaf growth and of stomatal conductance. With all 19 parameters held constant, AquaCrop simulated the fi nal aboveground biomass within 10% of the measured value for at least 8 of the 13 treatments (6 yr of experiments) and also the grain yield for at least fi ve of the cases. In at least four of the cases, the simulated results were within 5% of the measured for biomass as well as for grain yield. Th e largest deviation between the simulated and measured values was 22% for biomass, and 24% for grain yield. Importantly, the simulated pattern of canopy progression and biomass accumulation over time were close to those measured, with Willmott's index of agreement (d) for 11 of the 13 cases being ≥0.98 for canopy cover (CC), and ≥0.97 for biomass. Accelerated senescence of canopy due to water stress, however, proved to be diffi cult to simulate accurately; of the six cases, the index of agreement for the worst one was 0.957 for canopy and 0.915 for biomass. Possible reasons for the discrepancies between the simulated and measured results include simplifi cations in the model and inaccuracies in measurements. Th e usefulness of AquaCrop with well-calibrated conservative parameters in assessing water use effi ciency (WUE) of a crops under diff erent conditions and in devising strategies to improve WUE is discussed. area index; p, fractional depletion of total available water in the root zone; PWP, permanent wilting point; SWC, soil water content; Tr, crop transpiration; WP, water productivity (for biomass); WP*, normalized (for evaporative demand and atmospheric CO 2 ) water productivity (for biomass); WUE, water use effi ciency.

A lot of factors could affect a plant's photosynthetic activities like photosynthesis, respiration and transpiration and it could also affect a plant yield harvest. In this study, presence of light was observed and compared to partially shaded plants in terms of different parameters and the mean givens were compared. The materials used were pre-prepared in the laboratory. Corn (Zea mays) was used in testing the photosynthetic yield and respiration of plant with full or partial light. In transpiration, mussaenda (Mussaenda sp.) was used as the herbaceous leafy shoot and potometer as the device. The corn was oven-dried for a week to obtain the dry weight to be used in comparing its yield production. Also, transpiring mussaenda was observed in 3 minutes and the means were used for comparison. Based on the results, it showed that presence of light greatly influenced a plant growth development, and plants must have sufficient light to maintain the potential yield in its good condition. Lastly, light and wind intensity could also affect a plant's transpiration rate. Thus, high amount of light and wind increases transpiration rate but only up to some point because it might cause dryness on the plant surface.

The transpiration method was used to study the reaction of SiO 2 (cristobalite) with water vapor. Measurements were made between T = (1073 and 1728) K with water vapor contents from (0.05 to 0.6) by volume fraction in argon. From the results, the thermodynamic parameters for Si(OH) 4 (g) and SiO(OH) 2 (g) were determined. At T = (1073 to 1373) K, Si(OH) 4 is the primary vapor species and second law measurements lead to D f H (1200 K) = (À1344.6 ± 2.7) kJ AE mol À1 and S (1200 K) = (544.4 ± 2.1) J mol À1 K À1 . Third law measurements lead to D f H (298 K) = (À1351.3 ± 1.7) kJ AE mol À1 . These are in very good agreement with previous measurements and previous ab initio calculations. At T = (1673 and 1728) K, there is evidence of a second vapor species, SiO(OH) 2 (g). By subtracting the extrapolated Si(OH) 4 (g) pressure, it was possible to do a third law analysis and obtain a D f H (298 K) for SiO(OH) 2 (g) of (À836 ± 40) kJ AE mol À1 . Previous measurements and ab initio calculations are within this range.

Wang, Lawrence K. and Wang, Mu-Hao Sung (2022). Understanding evaporation, transpiration, evapotranspiration, precipitation and runoff volume for agricultural waste management.  In: "Evolutionary Progress in Science, Technology, Engineering, Arts, and Mathematics (STEAM)", Wang, Lawrence K. and Tsao, Hung-ping (editors).  Volume 4, Number 5, May 2022; pp.81. Lenox Institute Press, MA, USA. STEAM-VOL4-NUM5-MAY2022.  ISBN 978-0-9890870-3-2.  https://doi.org/10.17613/m8tf-zd10. ................ABSTRACT:  This is one of several updated UNIDO (United Nations Industrial Development Organization) training reports which were previously disseminated to developing countries for promoting the US green environmental biotechnology. This publication introduces (a) natural evaporation from water and land surfaces and the evaporation equations using either metric units or the US customary units; (b) natural transpiration and evapotranspiration phenomenon ; (c) the description, applications, limitations, design criteria and performance of evapotranspiration wastewater treatment process; (d) precipitation and the US historical 25-year 24-hour rainfall chart; (e) the parameters of dry-weather flows, runoff from rainfall, runoff from snowmelt, runoff volume (ROV), and total precipitation less evaporation (TPLE) value for storage pond design; (f) the temperature, effect of wind chill and wind chill equations using either metric units or the US customary units; (g) the adjusted mean monthly free water surface (FWS) evaporation for selected US stations; (h) the US annual FWS evaporation chart; (h) the US annual runoff from concrete or unsurfaced feedlots as percent of mean precipitation charts; (i) the US runoff from concrete or unsurfaced feedlots as percent of mean monthly precipitation charts; (j) the US criteria for siting, investigation and design of liquid manure storage facilities; (k) precipitation and condensation calculation; (l) the vapor pressure mathematical model and evaporation analysis for an agricultural storage pond; (m) a runoff determination example; (n) an example of runoff from an agricultural concrete feedlot; (n) an example of runoff from an earth feedlot; (o) an example of agricultural storage pond design ; and (p) glossary terms and research references. The US technical information, charts and examples presented in this publication are typical examples for developing countries to follow, in order to avoid or reduce the unnecessary non-point sources of agricultural pollution, in turn, to achieve the UNIDO's goal of sustainable industrial and agricultural development around the world.

Abstrak Transpirasi dipengaruhi oleh factor internal dan eksternal. Laju transpirasi mempunyai relasi dengan jenis tanaman dan populasi tanaman. Praktikum ini menguji transpirasi pada daun permukaan dorsiventral dengan mengukur presentase perubahan berat daun dan melihat adanya transpirasi pada daun menggunakan metode kertas kobalt. transpirasi stomata lebih cepat daripada transpirasi kutikula, ini mungkin disebabkan jumlah stomata lebih banyak daripada kutikula, dan dikarenakan letak kutikula di atas permukaan daun, masih ada organ tambahan pada tumbuhan yang dapat menghambat transpirasi di kutikula, seperti bulu-bulu halus di permukaan daun. Kertas kobalt yang telah di letakkan pada bagian atas dan bawah daun selama 15 menit terjadi perubahan warna. Perubahan warna pink pada bagian bawah daun menunjukkan tingginya tingkat kehilangan air daripada bagian atas daun. Perubahan warna biru menjadi merah muda menunjukkan telah terjadinya proses penguapan pada daun. Semakin lama warna kertas berubah maka semakin sedikit air yang diuapkan dari permukaan daun.

103204216 Pendidikan Biologi B 2010 UNIVERSITAS NEGERI SURABAYA FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM JURUSAN BIOLOGI 2012 BAB I PENDAHULUAN A. Latar Belakang Masalah Pada dasarnya semua tumbuhan hijau itu membutuhkan dan mengeluarkan air dalam setiap aktivitasnya. Tumbuhan mengeluarkan sejumlah air yang diserap dari dalam tanah ke lingkungan sekitar dalam bentuk uap air. Hilangnya sejumlah air dari dalam tumbuhan dalam bentuk uap air inilah yang disebut transpirasi. Proses transpirasi ini terjadi pada bagian tumbuhan yaitu stomata, kutikula dan lentisel. Namun, kebanyakan proses transpirasi yang dilakukan oleh tumbuhan, hampir semua air dikeluarkan melaui stomata. Proses transpirasi dimulai dengan penguapan air oleh sel-sel mesofil ke rongga antar sel yang ada dalam daun. Dalam hal ini rongga antar sel jaringan

Plantlets of Alocasia amazonica were regenerated on the MS medium supplemented with different concentrations (0-9%) of sucrose. An absence of sucrose in the growth medium induced generation of leaves, however, it decreased multiplication. On contrary, sucrose supply of 6% or 9% enhanced multiplication but hampered photoautotrophic growth (generation of leaves). Increasing sucrose supply also increased sugars and starch content and number of stomata and decreased water potential and size of stomata during in vitro growth period. During ex vitro acclimatization, shoot length, root length, leaf number and root number of Alocasia plantlets grown with 3% sucrose, were found to be better among the other studied sucrose concentrations. Under ex vitro acclimatization, number of stomata, contents of various carbohydrates in the leaves were increased but size of stomata decreased with increasing sucrose supply during in vitro growth period. Moreover, water potential of leaves of plantlets, which have been grown with a sucrose concentration other than 3%, was decreased. During in vitro growth, net CO 2 assimilation rate (P N ), transpiration (E), stomatal conductance (g s ) and variable fluorescence to maximum fluorescence ratio (Fv/ Fm) were unaffected, however, during acclimatization these were changed and maximum P N , E, and g s were observed in the plantlets micropropagated with 3% sucrose. Fv/Fm was decreased severely in the plantlets micropropagated with 6% sucrose during acclimatization. Thus a sucrose concentration of 3% in the medium is appeared to be better among studied concentrations for both in vitro growth and ex vitro acclimatization of A. amazonica plantlets.

Since about twenty years, hydraulic architecture (h.a.) is, doubtless, the major trend in the domain of plants (and especially trees) water relations. This review encompasses the main concepts and results concerning the hydraulic of architecture of trees. After a short paragraph about the definition of the h.a., the qualitative and quantitative characteristics of the h.a. are presented. This is an occasion to discuss the pipe model from the h.a. point of view. The second part starts with the central concept of embolism and give a review of important experimental results and questions concerning summer and winter embolism. The last part deals with the coupling between hydraulic and stomatal conductances. It discusses the theoretical and experimental relationships between transpiration and leaf water potential during a progressive soil drought, the increase of soil-root resistance and its consequences in term of xylem vulnerability, the factors controlling the daily maximum transpiration and how stomates can prevent "run away embolism". In conclusion different kinds of unsolved questions of h.a., which can be a matter of future investigations, are presented in addition with a classification of trees behaviour under drought conditions. To end, an appendix recalls the notions of water potential, pressure and tension.

This review describes physiological mechanisms and selectable indicators of gene action, with the aim of promoting new screening methods to identify genetic variation for increasing the salt tolerance of cereal crops. Physiological mechanisms that underlie traits for salt tolerance could be used to identify new genetic sources of salt tolerance. Important mechanisms of tolerance involve Na 1 exclusion from the transpiration stream, sequestration of Na 1 and Cl 2 in the vacuoles of root and leaf cells, and other processes that promote fast growth despite the osmotic stress of the salt outside the roots. Screening methods for these traits are discussed in relation to their use in breeding, particularly with respect to wheat. Precise phenotyping is the key to finding and introducing new genes for salt tolerance into crop plants.

In situ measurements and model simulations were used to analyse the spatial variations of wind speed (U) and leaf boundary layer conductance (g H b), and their effects on leaf transpiration and photosynthesis within the crown of a 20-year-old walnut tree (Juglans regia L.). Wind speed attenuation within the tree crown was strongly correlated to the cumulative leaf area along the wind path into the crown, as deduced from the 3D distribution of the tree foliage, obtained by the combined use of digitizing and allometric relationships. Simulations by the RATP model, i.e., a 3D numerical model of radiation transfer, leaf transpiration and photosynthesis (Sinoquet et al., 1999), were used (i) to study the spatial variations of transpiration, photosynthesis and leaf-to-atmosphere coupling within the tree crown; and (ii) to analyse coupling at tree level, in order to evaluate the sensitivity of total transpiration to climate variations. The main results of the simulations were: (i) spatial variations of stomatal conductance were mainly responsible for the important spatial variation of the leaf-to-air decoupling factor () within the tree crown; (ii) high coupling was observed at tree level, so that whole tree transpiration was primarily controlled by air VPD and secondarily by radiation; (iii) wind velocity and direction influenced only weakly the local transpiration, and had no effect on photosynthetic rates.

Evaporation is one of the inherent processes of the earth’s ecosystem. Water bodies, earth’s
surface and vegetation all contribute significantly towards the total evaporation which
eventually leads to the formation of clouds. The factors which affect the total evaporation
(evaporation & transpiration) are the surface temperature, ambient temperature, relative
humidity, external wind speed, pressure, surface area and geometry.
This thesis deals with the contributors of total evaporation individually viz. open water bodies;
soil-like surfaces; and leaf-like surfaces. A ceramic infrared heater has been used to mimic the
heating due to sun’s radiation in all the experiments which were conducted in the quiescent
atmosphere. This thesis has been broadly categorized into two parts: - (a) evaporation from
bare water surface; and (b) evaporation from a porous media. In part (a), we present
experimental results on the evaporation from a bare water surface heated either from above
using the infrared radiations or from below using immersed heaters. Heating from below leads
to unstable stratification and convection while infrared heating from above leads to stable
stratification. The effect of water-side convection on the evaporation from a bare water surface
has been investigated and all the experimental results have been combined to obtain a power
law relation between Sherwood number (Sh) and Rayleigh number (Ra). Part (b) of the thesis
has been further split into three major categories: - (1) evaporation from spheres based
conventional porous media; (2) evaporation from unconventional porous media containing
rods, capillaries, and plates; and (3) evaporation from leaf-like surfaces. In all the experiments, a
precision weighing balance was used to measure the evaporation rate. A thermal camera was
used to get the surface temperature fields, and fluorescein dye mixed with water gave insightful
results on the evaporation process. In particular the red deposits of fluorescein particles
revealed the evaporation sites. In most of the experiments, the infrared heating was of the order
of 1000W/m2. Different sized glass and acrylic containers were used in this thesis.
Mono-disperse glass beads (closest to mimic the natural soils), stainless steel balls, sieved
natural sand and hydrophobic Ball Grid Array balls have been used to create the spheres-based
conventional porous media. Evaporation was found to undergo three stages which depended on
the spheres size and the heat flux supplied. In the 1st stage of evaporation capillary film(s) pulls
water from beneath the porous media to the top surface and the evaporation rate remained
high, close to that obtained from a water surface. Capillary break-up occurs in the transition
regime which is followed by the 2nd stage of evaporation where a new vaporization plane is
formed within the porous media. In the 2nd stage, heat is conducted through the top dried layer
to the water below where evaporation takes place and the evaporation rate drops drastically.
Transition to 2nd stage happened earlier for coarser spheres at constant heat flux. Along with the
wetting properties, the spheres size has been found to effect capillary break-up length (a
measure of capillary film strength) and hence the duration of the stages of evaporation
drastically. Surface images captured using the thermal camera clearly showed the presence of
water till the capillary break-up. The capillary break-up length was also found to be affected
significantly by the heat flux. Apart from the experimental findings of mono-disperse spheres,
two layers of different sized glass spheres have also been investigated. The presence of
complicated network of textural layering in the earth’s surface is a well-known fact. Preferential
evaporation was clearly seen in the experiments with texturally layered porous media
independent of the orientation viz. vertical or horizontal layering. The stacking positions are
found to be critical in determining the overall evaporation characteristics.
The geometry of a pore between three spheres in mutual contact is very complicated. Simpler
pore geometry would be between two rods/plates in contact or three rods in mutual contact or
stacks of either of these two. We call these types of the porous media as “Unconventional porous
media” as they possess many unique features not shown by a conventional porous media. The
evaporation characteristics of vertically stacked rods was found to be dominated by the corner
films present in the near-zero radii contacts. Unlike the conventional porous media, the
capillary break-up length was found not to depend on the rod diameter. The capillary break-up
length for vertically stacked rods was larger than for the spheres case and was also found to be
independent of the heat flux, for the range investigated in this thesis. A mathematical model has
been developed for understanding the evaporation from the vertically stacked rods.
Experiments with horizontally stacked pencil leads showed early capillary break-up while with
horizontally stacked glass rods, capillary break-up was not observed. Experimental
investigations of porous media containing vertically stacked plates have also been studied.
Water trapped between two consecutive plates are treated as 2D source of evaporation.
Plants regulate their O2-CO2 content via tiny holes present on the leaves called “Stomata”. The
average size of a stoma is nearly 20μm and the total area covered by stomata is close to 5% of
the leaf area. However the higher transpiration rates (60-70 % compared to a bare water
source) sustained by a plant has remained a mystery for the phytologists. In view of this we
mimic the leaf-type using regularly spaced holes on the silicon wafers from which water
evaporates. The leaf-mimics had different hole-diameter but open area ratio was kept constant.
In all the cases the evaporation ratio (ratio of the evaporation rate from the leaf mimic to that of
the evaporation rate of a bare water surface at the same surface temperature) was found to
increase at lower heat fluxes. With increasing the hole-size evaporation rate was found to
decrease. The leaf-mimic with the smallest hole-size had the highest evaporation rate and the
evaporation ratio increased from 0.46 at 800W/m2 to 0.64 at 400W/m2. The 3D nature of
diffusion near these tiny holes enhances the evaporative flux which explains the high
evaporation rates even for low open area ratios.

Water, the most important component of life, is rapidly becoming a critically short commodity for humans and crop production. Limited water supply is one of the major abiotic factors that adversely affect agricultural crop production worldwide. Drought stress influences the normal physiology and growth of plants in many ways. It results in an increase of solute concentration outside the roots compared to the internal environment of the root and causes reverse osmosis. As a result, the cell membrane shrinks from the cell wall and may eventually lead to death of the cell. Water stress tends to shrink away from the interface with water-absorbing roots, creating a gap in the soil-plant-air continuum. As the plant continues to lose water via transpiration, water is drawn from root cells resulting in shrinkage of cell membranes and results in decreased integrity of the cell membrane and the living cell may be destroyed. Drought stress inhibits photosynthesis in plants by closing stomata and damaging the chlorophyll contents and photosynthetic apparatus. It disturbs the balance between the production of reactive oxygen species (ROS) and the antioxidant defence, causing accumulation of ROS which induces oxidative stress to proteins, membrane lipids and other cellular component. Mineral elements have numerous functions in plants including maintaining charge balance, electron carriers, structural components, enzyme activation, and providing osmoticum for turgor and growth .In this paper, an overview of some macronutrients (nitrogen, phosphorus, potassium, calcium and magnesium), micronutrients (Zinc, Boron, Copper) and silicon has been discussed in detail as how these nutrients play their role in decreasing the adverse effects of drought in crop plant.

The model RATP (radiation absorption, transpiration and photosynthesis) is presented. The model was designed to simulate the spatial distribution of radiation and leaf-gas exchanges within vegetation canopies as a function of canopy structure, canopy microclimate within the canopy and physical and physiological leaf properties. The model uses a three-dimensional (3D) representation of the canopy (i.e. an array of 3D cells, each characterized by a leaf area density). Radiation transfer is computed by a turbid medium analogy, transpiration by the leaf energy budget approach, and photosynthesis by the Farquhar model, each applied for sunlit and shaded leaves at the individual 3D cell-scale. The model typically operates at a 20–30 min time step. The RATP model was applied to an isolated, 20-year- old walnut tree grown in the field. The spatial distribution of wind speed, stomatal response to environmental variables, and light acclimation of leaf photosynthetic proper- ties were taken into account. Model outputs were compared with data acquired in the field. The model was shown to simulate satisfactorily the intracrown distribution of radiation regime, transpiration and photosynthetic rates, at shoot or branch scales.

The gas exchange of 19 widely different warm climate species was observed at different leaf to air vapour pressure deficits (VPD). In all species stomata tended to close as VPD increased resulting in a decrease in net photosynthesis. The absolute reduction in leaf conductance per unit increase in VPD was greatest in those species which had a large leaf conductance at low VPDs. This would be expected even if stomata of all species were equally sensitive. However the percentage reduction in net photosynthesis (used as a measure of the relative sensitivity of stomata of the different species) was also closely related to the maximal conductance at low VPD. Similarily the relative sensitivity of stomata to changes in VPD was closely related to the weighted stomatal density or ‘crowding index’. The hypothesis is presented that stomatal closure at different VPDs is related to peristomatal evaporation coupled with a high resistance between the epidermis and the mesophyll and low resistance between the stomatal apparatus and the epidermal cells. This hypothesis is consistent with the greater relative sensitivity of stomata on leaves with a high crowding index. The results and the hypothesis are discussed in the light of selection, for optimal productivity under differing conditions of relative humidity and soil water availablility, by observation of stomatal density and distribution on the two sides of the leaf.

At suboptimal temperatures, anthocyanins accumulate in the illuminated leaf surface of some maize genotypes and, if the anthocyanins shade chloroplasts, they can effectively reduce the risk of photo-inhibition but also photosynthesis. To investigate this phenomenon, gas exchange, fluorescence, superoxide dismutase activity and xanthophyll composition of anthocyanin-containing HOPI and anthocyanin-deficient W22 maize genotypes were measured in either white or red light, where the latter is not absorbed by anthocyanins. Despite differences in light absorption in chloroplasts, photosynthesis did not differ between HOPI and W22 under either light source, suggesting that neither CO 2 supply nor photochemistry were more limiting in red leaves than in green leaves. In fact, no major differences in transpiration were detected. The ∆ ∆ ∆ ∆ F / F m (photosystem II quantum yield) of HOPI in white light was higher than in red light and higher than ∆ ∆ ∆ ∆ F / F m of W22 with either light source. This probably compensated for the lower white light absorption of HOPI chloroplasts compared with W22 because of the presence of anthocyanins and led to similar rates of calculated electron transport for both genotypes. After exposure to high white light at 5 °°°° C, xanthophyll de-epoxidation and superoxide dismutase activity were lower in HOPI than in W22. Further, HOPI could be exposed to a much higher irradiance than W22 before F v / F m was reduced to that of W22.

High temperatures and high atmospheric vapor pressure deficits (VPDs) are usually encountered in greenhouses in hot climates. For citrus, these environmental conditions can lead to decreases in photosynthetic activity with detrimental effects on plant growth. The aim of this study was to evaluate the use of reflective aluminized polypropylene shading nets on photosynthetic performance of citrus plants, by measuring CO 2 assimilation, transpiration rate, stomatal conductance and chlorophyll a fluorescence. Incident photosynthetically active radiation (PAR) levels and leaf temperatures were reduced when the reflective nets were used. Higher stomatal conductance and higher CO 2 assimilation rates were observed in shaded plants, so that integrated daily net CO 2 uptake was approximately 20% higher than in exposed plants. The better performance of shaded plants, however, was observed only during the middle of the day, being PAR-limited in early morning and late afternoon. The reflective net was also effective in preventing photoinhibition of photosynthesis in shaded plants, which sustained higher maximum (F v /F m ) and effective ðDF=F 0 m Þ quantum yield with higher apparent electron transport rates (ETRs) than exposed plants. Observed photoinhibition in exposed plants was transient, probably reflecting photosynthetic regulatory responses to excess absorbed light energy. Therefore, the results clearly showed that photosynthetic performance of citrus cultivated in greenhouses can be improved by the use of reflective nets. Favorable effects comprised not only the maintenance of proper stomatal aperture for gas exchange but also a better functioning of the photosystem II (PSII) under nonphotoinhibitory conditions. # 2002 Published by Elsevier Science B.V.

Climate variability and climate change induce important intra-and inter-annual variability of precipitation that significantly alters the hydrologic cycle. The surface water budgets and the plant or ecosystem water use efficiency (WUE) are in turn modified. Obtaining greater insight into how climatic variability and agricultural practices affect water budgets and regarding their components in croplands is, thus, important for adapting crop management and limiting water losses. Therefore, the principal objectives of this study are: 1) to assess the contribution of different components to the agro-ecosystem water budget and 2) to evaluate how agricultural practices and climate modify the components of the surface water budget. To achieve these goals, we tested a new method for partitioning evapotranspiration (ETR), measured by means of an eddy-covariance method, into soil evaporation (E) and plant transpiration (TR) based on marginal distribution sampling (MDS). The partitioning method proposed requires continuous flux recording and measurements of soil temperature and humidity close to the surface, global radiation above the canopy and assessment of leaf area index dynamics. This method is well suited for crops because it requires a dataset including long bare-soil periods alternating with vegetated periods for accurate partitioning estimation. We compared these estimations with calibrated simulations of the ICARE-SVAT double source mechanistic model.The results showed good agreement between the two partitioning methods, demonstrating that MDS is a convenient, simple and robust tool for estimating E with reasonable associated uncertainties. During the growing season, the proportion of E in ETR was approximately one-third and varied mainly with crop leaf area. When calculated on an annual time scale, the proportion of E in ETR reached more than 50%, depending on the crop leaf area and on the duration and distribution of bare soil within the year.

Deuterium, a stable isotope of tritium, was released into a vinyl house in autumn 1995 and summer 1996 to study the transfer of tritium from air to plant and soil. Temporal variation of D 2 O concentrations in plant and soil water, and plant physiological parameters such as transpiration rate and leaf temperature, were measured during these experiments. D 2 O concentrations of plants were fitted to a first order kinetic model: C p = C max (1− e − kt ), where C p is the D 2 O concentrations in plants at time t, C max is the steady-state concentration in plants and k is the rate constant. The rate constant was also calculated using measured plant physiological parameters for comparison. The D 2 O uptake by paddy rice was most rapid and the value of k was 3.639 0.31 h − 1 followed by radish, cherry tomato, Komatsuna and orange. The day/night concentration ratio for cherry tomato and orange was higher than that for radish and Komatsuna.

An experiment was carried out in a naturally ventilated greenhouse to study the relationship between banana (Musa sp.) plant transpiration (Tr) measured with load cells, reference crop evapotranspiration (ETo) calculated with five widely used models (i.e. the Priestley-Taylor, FAO radiation, Hargreaves, FAO Penman and FAO Penman-Monteith models) and pan evaporation (Epan) measured with a standard Chinese 20 cm pan. Microclimatic conditions were measured inside the greenhouse. Results show that vapor pressure deficit and air temperature had good linear correlations to banana Tr with R2 of 0.67 and 0.62, respectively. Among the five models tested, banana Tr and ETo calculated with the FAO-Penman model yielded the highest determination coefficient (R2 = 0.67), followed by the FAO-PM model (R2=0.63), the FAO radiation model (R2=0.52), the Hargreaves model (R2=0.49) and the Priestley-Taylor model (R2=0.47). Banana transpiration Tr vs. Epan yielded an R2 of 0.83, which is higher than the five models tested. In conclusion, the 20 cm pan can be useful for estimating banana Tr in greenhouses.

A rule-based, fuzzy logic crop water stress index (FL-CWSI) was developed using growth chamber data and tested on tall fescue canopies grown in the greenhouse. The FL-CWSI always gives an index value between zero and one. The selection of the FL-CWSI defuzzification methods-center of area (COA) or mean of maxima (MOM) is not important. COA and MOM defuzzification tests were quite similar for the growth chamber conditions (r 2 = 0.92) and greenhouse conditions (r 2 = 0.99), respectively. FL-CWSI values correlated well for growth chamber CWSI values (r 2 = 0.70) and reasonably well for the greenhouse (r 2 = 0.50). The results also demonstrated that FL-CWSI with 150 rules predicts the correct water stress development trend, similar to the empirical and more complex theoretical CWSI methods. FL-CWSI eliminated the necessity for measurements of canopy resistance, aerodynamic resistance, and soil heat flux, needed for predicting theoretical crop water stress indices. A FL-CWSI rule system is attractive for turf irrigation control, because it can be easily adapted and programmed on commercial micro-controllers.

Vetiver (Vetiveria zizanioides) has not been widely introduced in arid and semi-arid regions where irrigation, fertilization, and salinity are important factors in plant growth. The main objective of this study was to determine the response of vetiver to fertilization (fertigation) and salinity and their interactions under irrigated conditions. The experiment was conducted in a greenhouse in 10-L pots. Combined effects of three nutrients concentrations and three salinity levels of electrical conductivity (EC) 1, 3 and 6 dS/m in the irrigation water on growth and transpiration of vetiver plants and the content of different elements in their foliage were studied. Similar contents of w3.7 g/kg Na, w5.77 g/kg Ca and w2.55 g/kg Mg were found in the foliage of all the plants irrigated with the different fertilizer and salinity levels. Concentrations of 59 mg/L N and 36.1 mg/L K in the irrigation water were sufficient for vetiver plants needs at the different salinity levels tested. The salinity threshold (the maximum EC in the soil solution that does not cause a significant yield reduction) for vetiver was between 3 and 6 dS/m. A concentration of 15.2 mg/L P in the irrigation water was the optimum value for vetiver growth in the three salinity levels, resulting in an average content of 5.95 g/kg P in plant foliage. It is suggested that vetiver is sensitive to excess P (>8.66 g/kg). Increasing EC in the irrigation water to 6 dS/m decreased plant foliage biomass mainly due to an increase in the osmotic potential of the irrigation water and high Cl À concentration in the foliage.

The degree of salt tolerance of two newly developed genotypes of spring wheat, S24 and S36 was assessed with respect to their parents, LU26S (from Pakistan) and Kharchia (from India). These four lines along with a salt-tolerant genotype SARC-1 and two salt-sensitive cvs Potohar and Yecora Rojo were subjected to salinized sand culture containing 0, 125 or 250 mol m−3 NaCl in full strength Hoagland's nutrient solution.S24 produced significantly greater grain yield and had greater 1000 seed weight and number of tillers per plant than those of the other cultivars /lines. S36 was not significantly different from its parents in seed yield and yield components. SARC-1 was the second highest in grain yield of all cultivars/lines, but it did not differ significantly from LU26S and Kharchia in 1000 seed weight and number of tillers per plant.The greater degree of salt tolerance of S24 could be related to its lower accumulation of Na+ in the leaves and maintenance of higher leaf K/Na ratios and K versus Na selectivity as compared to its parents. S36, which was as good as its parents in growth, also had lower Na+ and higher K/Na ratios and K versus Na selectivity in the leaves at the highest salt level than those in its parents. SARC-1 did not differ from LU26S and Kharchia in ionic content or K/Na ratios and K versus Na selectivities of both leaves and roots. Both the salt-sensitive cultivars, Potohar and Yecora Rojo, had significantly greater leaf Na+ and Cl− concentrations and lower leaf K/Na ratios and K versus Na selectivities than all the salt-tolerant lines examined in this study.From this study it is evident that improvement in salt tolerance of spring wheat is possible through selection and breeding, and pattern of ion accumulation is not consistent among the salt-tolerant genotypes in relation to their degree of salt tolerance.

One-year-old seedlings of Quercus robur L., Q. petraea (Matt.) Liebl. and Fagus sylvatica L. were cultivated in lysimeters and subjected to waterlogging for 17 weeks, interrupted by a five-week drainage period during summer. The growth of Q. robur was less affected by waterlogging than that of Q. petraea and Fagus. Waterlogging resulted in the formation of adventitious roots in Q. robur and Q. petraea, but not in Fagus. In contrast to Fagus, Q. robur and, to a lesser extent, Q. petraea were able to generate roots even below the water table. The hydraulic conductance of the excised root systems, the stomatal conductance and, in Fagus, the leaf water potential and the leaf-mass related hydraulic conductance were decreased by waterlogging. The decrease in the hydraulic conductance was largest in Fagus, and smallest in Q. robur. The roots of Fagus responded to anaerobic conditions with an increase in ethanol concentration. The measurements of nitrate reductase activities in roots and leaves provided no indications of a persistent contribution of NO 3 − metabolism to the alleviation of waterlogging-induced stress. It is concluded that Q. robur and, to a lesser extent, Q. petraea can tolerate waterlogging periods better than Fagus due to a different pattern of root formation, and to a better adjustment of leaf biomass production to the hydraulic conductivity of the root system.

Although climate change will alter both soil water availability and evaporative demand, our understanding of how future climate conditions will alter tree hydraulic architecture is limited. Here, we demonstrate that growth at elevated temperatures (ambient +5°C) affects hydraulic traits in seedlings of the deciduous boreal tree species Populus tremuloides, with the strength of the effect varying with the plant organ studied. Temperature altered the partitioning of hydraulic resistance, with greater resistance attributed to stems and less to roots in warm-grown seedlings (P < 0.02), and a 46% (but marginally significant, P = 0.08) increase in whole plant conductance at elevated temperature. Vulnerability to cavitation was greater in leaves grown at high than at ambient temperatures, but vulnerability in stems was similar between treatments. A soil-plant-atmosphere (SPA) model suggests that these coordinated changes in hydraulic physiology would lead to more frequent drought stress and reduced water-use efficiency in aspen that develop at warmer temperatures. Tissue-specific trade-offs in hydraulic traits in response to high growth temperatures would be difficult to detect when relying solely on whole plant measurements, but may have large-scale ecological implications for plant water use, carbon cycling and, possibly, plant drought survival.

Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m−2s−1), temperatures (20, 25, 30, 35 and 40 °C) and CO2 concentrations (250, 350, 450, 550, 650 and 750 μmol mol−1) on gas and water vapour exchange characteristics of Cannabis sativa L. were studied to determine the suitable and efficient environmental conditions for its indoor mass cultivation for pharmaceutical uses. The rate of photosynthesis (PN) and water use efficiency (WUE) of Cannabis sativa increased with photosynthetic photon flux densities (PPFD) at the lower temperatures (20–25 °C). At 30 °C, PN and WUE increased only up to 1500 μmol m−2s−1 PPFD and decreased at higher light levels. The maximum rate of photosynthesis (PN max) was observed at 30 °C and under 1500 μmol m−2s−1 PPFD. The rate of transpiration (E) responded positively to increased PPFD and temperature up to the highest levels tested (2000 μmol m−2s−1 and 40 °C). Similar to E, leaf stomatal conductance (gs) also increased with PPFD irrespective of temperature. However, gs increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on gs in this species. Overall, high temperature and high PPFD showed an adverse effect on PN and WUE. A continuous decrease in intercellular CO2 concentration (Ci) and therefore, in the ratio of intercellular CO2 to ambient CO2 concentration (Ci/Ca) was observed with the increase in temperature and PPFD. However, the decrease was less pronounced at light intensities above 1500 μmol m−2s−1. In view of these results, temperature and light optima for photosynthesis was concluded to be at 25–30 °C and ∼1500 μmol m−2s−1 respectively. Furthermore, plants were also exposed to different concentrations of CO2 (250, 350, 450, 550, 650 and 750 μmol mol−1) under optimum PPFD and temperature conditions to assess their photosynthetic response. Rate of photosynthesis, WUE and Ci decreased by 50 %, 53 % and 10 % respectively, and Ci/Ca, E and gs increased by 25 %, 7 % and 3 % respectively when measurements were made at 250 μmol mol-1 as compared to ambient CO2 (350 μmol mol−1) level. Elevated CO2 concentration (750 μmol mol−1) suppressed E and gs ∼ 29% and 42% respectively, and stimulated PN, WUE and Ci by 50 %, 111 % and 115 % respectively as compared to ambient CO2 concentration. The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol m−2s−1 PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2 concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment.

Hubungan antara laju transpirasi dengan jumlah stomata per luasan daun yaitu, semakin banyaknya jumlah stomata akan memperbesar transpirasi. Distribusi stomata sangat berhubungan dengan kecepatan transpirasi pada daun yaitu misalnya letak satu sama lain dengan jarak tertentu. Dalam batas tertentu, semakin banyak porinya maka semakin cepat penguapan air. Jika lubang-lubang itu terlalu berdekatan, maka penguapan dari lubang yang satu akan menghambat penguapan lubang yang ada didekatnya. Luasan daun juga berpengaruh karena daun yang luas memiiki jumlah stomata yang banyak, sehingga mengakibatkan tingginya laju transpirasi.

A modified Jarvis-Stewart model of canopy transpiration (E c ) was tested over five ecosystems differing in climate, soil type and species composition. The aims of this study were to investigate the model's applicability over multiple ecosystems; to determine whether the number of model parameters could be reduced by assuming that site-specific responses of E c to solar radiation, vapour pressure deficit and soil moisture content vary little between sites; and to examine convergence of behaviour of canopy water-use across multiple sites. This was accomplished by the following: (i) calibrating the model for each site to determine a set of site-specific (SS) parameters, and (ii) calibrating the model for all sites simultaneously to determine a set of combined sites (CS) parameters. The performance of both models was compared with measured E c data and a statistical benchmark using an artificial neural network (ANN). Both the CS and SS models performed well, explaining hourly and daily variation in E c . The SS model produced slightly better model statistics [R 2 = 0.75-0.91; model efficiency (ME) = 0.53-0.81; root mean square error (RMSE) = 0.0015-0.0280 mm h -1 ] than the CS model (R 2 = 0.68-0.87; ME = 0.45-0.72; RMSE = 0.0023-0.0164 mm h -1 ). Both were highly comparable with the ANN (R 2 = 0.77-0.90; ME = 0.58-0.80; RMSE = 0.0007-0.0122 mm h -1 ). These results indicate that the response of canopy water-use to abiotic drivers displayed significant convergence across sites, but the absolute magnitude of E c was site specific. Period totals estimated with the modified Jarvis-Stewart model provided close approximations of observed totals, demonstrating the effectiveness of this model as a tool aiding water resource management. Analysis of the measured diel patterns of water use revealed significant nocturnal transpiration (9-18% of total water use by the canopy), but no Jarvis-Stewart formulations are able to capture this because of the dependence of water-use on solar radiation, which is zero at night. c (mm hr −1 ) E c (mm hr −1 ) . Monthly ensembles of mean measured canopy transpiration (E c , ○) for the (a) WNSWEW, (b-c) ENSWEW, (d) VicEF, (e-g) TasEP and (h) WABW sites. The solid dark-grey and light-grey lines represent the SS and CS modelled, mean monthly diurnal course of E c respectively. The black dashed line represents the statistical benchmark constructed using the artificial neural network (ANN). The grey-shaded region represents the absolute difference between observed and ANN E c and is the region of 'good model performance'

The aim of this study was to investigate the biochemical, physiological and morphological responses of sugarcane to isoosmotic salt and water-deficit stress. Disease-free sugarcane plantlets derived from meristem cuttings were photoautotrophically grown in MS media and subsequently exposed to -0.23 (control), -0.67 or -1.20 MPa iso-osmotic NaCl (salt stress) or mannitol (water-deficit stress). Chlorophyll a (Chl a), chlorophyll b (Chl b), total carotenoids (C x+c ), maximum quantum yield of PSII (Fv/Fm), photon yield of PSII ( PSII), stomatal conductance (Gs) and transpiration rate (E) in the stressed plantlets were significantly reduced when compared to those of plantlets of the control group (without mannitol or NaCl), leading to net-photosynthetic rate (Pn) and growth reduction with positive correlation. In addition, physiological changes and growth parameters of plantlets in the salt stress conditions were more sharply reduced than those in waterdeficit stress conditions. On the other hand, the proline content and non-photochemical quenching (NPQ) in the leaves of stressed plantlets increased significantly, especially in response to iso-osmotic salt stress. The chlorophyll pigments in iso-osmotic stressed leaves were significantly degraded (r 2 = 0.93), related to low water oxidation (r 2 = 0.87), low netphotosynthetic rate (r 2 = 0.81), and growth reduction (r 2 = 0.97). The multivariate biochemical, physiological and growth parameters in the present study should be further used to develop salt, or drought, tolerance indices in sugarcane breeding programs.

Oxygen isotopes in precipitation and soil water were monitored at two sites along a climate gradient on the east side of the Cascade Mountains (Washington, USA). Precipitation at both sites is dominated by snowfall in the winter months. d 18 O values of precipitation show a typical seasonal variation from around À17& in the winter to around À8& in the summer at the western site (Cle Elum), and slightly lower values at the eastern site (Ellensburg). Soil water isotope composition and moisture contents relate to hydrological season: (1) late summer to fall-cooling, increased soil moisture; (2) winter-snow cover; (3) late winter to early spring-snow melts, recharge of soils and groundwater; (4) late spring-initial drying of soils. A simple mass balance model that conserves isotopes and mass is used to constrain the rates of water loss due to evaporation and non-fractionating losses (transpiration and downward percolation) during these hydrological seasons. Non-fractionating losses at both sites are similar during the spring at approximately 0.8-1.0 mm/day. In contrast, during the fall, these non-fractionating losses are near zero at the drier site (Ellensburg) and remain at %0.8 mm/day at the wetter site (Cle Elum). The model yields evaporation rates between 0.01 and 0.2 mm/day for Ellensburg and between 0.2 and 0.9 mm/day for Cle Elum.