scholarly journals TRANSPIRAÇÃO FOLIAR E CONDUTÂNCIA ESTOMÁTICA DA CANA-DE-AÇÚCAR EM FUNÇÃO DO CLIMA E DISPONIBILIDADE DE ÁGUA

Irriga ◽  
2017 ◽  
Vol 22 (4) ◽  
pp. 675-689
Author(s):  
Gustavo Cavalari Barboza ◽  
José Teixeira Filho
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Photosynthetically Active Radiation ◽  
Vapour Pressure Deficit ◽  
Weather Conditions ◽  
Gas Analyzer ◽  
Active Radiation ◽  
Agricultural Engineering ◽  
Leaf Transpiration ◽  
Infrared Gas Analyzer

TRANSPIRAÇÃO FOLIAR E CONDUTÂNCIA ESTOMÁTICA DA CANA-DE-AÇÚCAR EM FUNÇÃO DO CLIMA E DISPONIBILIDADE DE ÁGUA  GUSTAVO CAVALARI BARBOZA¹ E JOSÉ TEIXEIRA FILHO² ¹ Faculdade de Engenharia Agrícola, UNICAMP – Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz, Campinas- SP – Brasil. CEP:13083-875, [email protected]. ² Faculdade de Engenharia Agrícola, UNICAMP – Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz, Campinas- SP – Brasil. CEP:13083-875, [email protected].  1 RESUMO Diversos trabalhos utilizam da porometria como metodologia para quantificar a transferência de água para a atmosfera. No entanto, para a cana-de-açúcar essa metodologia é escassa. Assim, o objetivo do trabalho foi verificar o comportamento da transpiração foliar (E) e da condutância estomática (Gs) da cana-de-açúcar em função da radiação fotossinteticamente ativa (PAR) e do deficit de pressão de vapor (DPV), e correlacionar com os diferentes potenciais hídricos das plantas (Ψpd). Esse experimento foi conduzido na área experimental da Faculdade de Engenharia Agrícola da Universidade Estadual de Campinas, no qual foi instalada uma parcela de cana-de-açúcar, variedade RB867515 e utilizado o analisador automático de fotossíntese - IRGA LI6400XT, na escala horária. A partir dos resultados, conclui-se que os valores de E e Gs estão correlacionados positivamente com as condições meteorológicas e também com a disponibilidade de água no solo. Palavras-chave: Trocas gasosas, potencial hídrico foliar, radiação fotossinteticamente ativa.  BARBOZA, G. C.; TEIXEIRA FILHO, J.LEAF TRANSPIRATION AND STOMATAL CONDUCTANCE OF SUGARCANE IN FUNCTION OF WEATHER AND AVAILABILITY OF WATER  2 ABSTRACT There are several studies using porometry as method to quantify the transfer of water to the atmosphere. However, for sugarcane this methodology is scarce. The objective of the study was to investigate the behavior of leaf transpiration (E) and stomatal conductance (Gs) of sugarcane in function of photosynthetically active radiation (PAR) and vapour-pressure deficit (VPD), and to correlate with the different water potential of plants (Ψpd). This experiment was conducted in the experimental area of the Faculty of Agricultural Engineering/UNICAMP, where was installed a parcel of sugarcane, RB867515 variety was installed, and a infrared gas analyzer - IRGA LI6400XT was used in hourly scale. Based on the results, it is concluded that the values of E and Gs are positively correlated with the weather conditions and with the availability of water in the soil. Keywords: Gas Exchange, leaf water potential, photosynthetically active radiation.

Gas exchange processes of yellow-cedar (Chamaecyparis nootkatensis) in response to environmental variables

1991 ◽  
Vol 69 (12) ◽  
pp. 2684-2691 ◽  
Author(s):  
Steven C. Grossnickle ◽  
John H. Russell
Keyword(s):  
Stomatal Conductance ◽  
Response Surface ◽  
Photosynthetically Active Radiation ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Surface Model ◽  
Root Temperature ◽  
Active Radiation ◽  
Chamaecyparis Nootkatensis ◽  
Exchange Processes

Yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) gas exchange processes were measured in response to the following primary environmental variables: photosynthetically active radiation, vapour pressure deficit, root temperature, and soil moisture. Under nonlimiting edaphic conditions, maximum stomatal conductance and maximum CO2 assimilation increased rapidly as photosynthetically active radiation increased from 0 to 200 μmol∙m−2∙s−1 and from 0 to 500 μmol∙m−2∙s−1, respectively. Thereafter, greater photosynthetically active radiation levels only resulted in minor increases in stomatal conductance and CO2 assimilation. Maximum stomatal conductance and maximum CO2 assimilation declined in a concave manner as vapour pressure deficit increased from 1 to 5 kPa. Response surface model for stomatal conductance showed vapour pressure deficit was the primary influence after light had caused initial stomatal opening. Response surface modeling approach showed CO2 assimilation increased as photosynthetically active radiation increased, but increased vapour pressure deficit resulted in a suppression of CO2 assimilation. Response surface model showed internal CO2 concentration declined sharply as photosynthetically active radiation increased from 0 to 500 μmol∙m−2∙s−1, but it remained constant with increasing vapour pressure deficit. Decreasing root temperature resulted in a continual decline in CO2 assimilation and stomatal conductance from 22 to 1 °C, while internal CO2 concentration declined from 22 to 13 °C with little change between 13 and 1 °C. As predawn shoot water potential decreased from −0.5 to −2.0 MPa, CO2 assimilation declined in a linear manner, while stomatal conductance and internal CO2 concentration declined in a concave manner. Key words: Chamaecyparis nootkatensis, CO2 assimilation, stomatal conductance, internal CO2 concentration, photosynthetically active radiation, vapour pressure deficit, root temperature, predawn shoot water potential.

Relationship between Photosynthetic Rate and Stomatal Conductance, Intercellular CO2 Concentration, Transpiration Rate, Vapour Pressure Deficit and Photosynthetically Active Radiation in Sweet Corn (Zea mays)

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Aidee Kamal Khamis ◽  
◽  
Umi Aisah Asli ◽  
Mohd Nadzreen Hidaya Sarjuni ◽  
Mohd Azlan Jalal ◽  
...  
Keyword(s):  
Zea Mays ◽  
Stomatal Conductance ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Photosynthetically Active Radiation ◽  
Vapour Pressure ◽  
Sweet Corn ◽  
Vapour Pressure Deficit ◽  
Active Radiation ◽  
Development Stages

Sweet corn (Zea mays) is thethird-largest plantation crop in Malaysia. Since it is cultivated mainly for the corncobs, the reproductive and kernel development stages are critical for high yields. Photosynthesis measurement can be used as a major approach to improve photosynthetic efficiency, which can directly affect yield. Additionally, plant nutrient uptake also plays a major role in yield quantity and quality. Conventional fertilisation(chemical and/or organic) may result in excessive fertilizer input, which is detrimental to the environment. We therefore investigated the relationship between photosynthetic rate and stomatal conductance (gs), intercellular CO2concentration (Ci), transpiration rate and vapour pressure deficit based on leaf temperature (VpdL) and photosynthetically active radiation (PAR) during the growth and development stages of sweet corn. The seeds were subjected to the germination test to assess viability and were then planted at a distance of 10 cm both between plantsand rows (replicates). A total of eight subplots (2.2 m long, 60 cm wide, 30 cm high) were prepared in a randomized complete block design (RCBD). Leaf gas exchange measurements were carried out at days 10, 20, 30, 40, 50 and 60 at 9:00 a.m. in the morning and 4:00 p.m. in the evening. Three uniform plants were selected from each replicate and used for measurements throughout the experiment. At day 30, photosynthesis started to decline and was largely unaffected by the set environmental conditions, although stomatal conductance remained high. This can be attributed to the energy diversion from vegetative stages to reproductive stages. Therefore, fertilising practices should be synchronised to match the plant stages for more sustainable and efficient fertilisation and to obtain maximum yield.

TROCAS GASOSAS EM PLANTAS DE CANA-DE-AÇÚCAR INOCULADAS COM GLUCONACETOBACTER DIAZOTROPHICUS E SUBMETIDAS AOS ESTRESSES SALINO E HÍDRICO

2020 ◽  
Vol 03 (01) ◽  
pp. 57-63
Author(s):  
Janice Dias ◽  
Keyword(s):  
Abiotic Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Endophytic Bacteria ◽  
Gluconacetobacter Diazotrophicus ◽  
Gas Analyzer ◽  
Sugarcane Crop ◽  
Lower Productivity ◽  
High Doses ◽  
Infrared Gas Analyzer

The sugarcane crop isconsidered moderately sensitive to environmental stresses, which results in reduced growth and lower productivity. In addition, there is a need for the application of high doses of nitrogen fertilizer. A potential and agroecologically correct alternative is the use of nitrogen-fixing endophytic bacteria, such as Gluconacetobacter diazotrophicus. However, under conditions of abiotic stress the benefits from this plant-endophyte association can be altered due to the physiology of stress response. The objective of this work was to study the effect of inoculation of G. diazotrophicus by means of the evaluation of the parameters of gas exchange, in sugarcane plants submitted to salt and water stresses. The rates of stomatal conductance, transpiration and liquid photosynthesis were evaluated by means of a portable infrared gas analyzer (IRGA). The results showed that the presence of the bacteria may alter the rates of stomatal conductance and transpiration, interfering in the physiology of response to salinity and drought. Keywords: Endophytic bactéria. Stomatal conductance. Transpiration. Salinity. Drought.

scholarly journals Emerald zoyzia grass development regarding photosynthetically active radiation in different slopes

2012 ◽  
Vol 32 (3) ◽  
pp. 501-509 ◽  
Author(s):  
Ruchele M. Coan ◽  
José E. P. Turco ◽  
Kathia F. L. Pivetta ◽  
Madson N. da Costa ◽  
Caroline de M. D'A. Mateus
Keyword(s):  
Photosynthetically Active Radiation ◽  
Dry Matter ◽  
Global Radiation ◽  
Global Solar Radiation ◽  
State University ◽  
Active Radiation ◽  
Agricultural Engineering ◽  
Paulo State ◽  
Tukey Test ◽  
Engineering Department

With this study, the objective was to estimate the photosynthetically active radiation (PAR) and to correlate it with the dry matter (MMSPA) of the emerald zoysia (Zoysia japonica Steud.) on surfaces with different expositions and slopes. The research was conducted at the Experimental Watershed of the Agricultural Engineering Department, School of Agriculture and Veterinary Sciences of São Paulo State University (FCAV/UNESP), Brazil, where the surfaces (H, 10 N, 30 N, 50 N, 10 S, 30 S, 50 S, 10 L, 30 L, 50 L, 10 O, 30 O and 50 O) were used. To obtain the global solar radiation, it was installed an automated weather station where the PAR (dependent variable) was obtained by the equation y = a + bx, and the global radiation was independent. To compare means of MMSPA, it was used the Tukey test at 5% probability, and to assess the relation PAR/MMSPA, the simple linear correlation coefficient. The result showed that the accumulation of these effects in the PAR increases with North exposure and decreases with the South, and exposure to 50N is most suitable for slopes, not having correlation between the PAR and the MMSPA for the surfaces evaluated for the study period.

The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field

1976 ◽  
Vol 273 (927) ◽  
pp. 593-610 ◽  
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Vapour Pressure ◽  
Environmental Variables ◽  
Turgor Pressure ◽  
Radiant Energy ◽  
Vapour Pressure Deficit ◽  
Leaf Water ◽  
Scatter Diagram

Attempts to correlate values of stomatal conductance and leaf water potential with particular environmental variables in the field are generally of only limited success because they are simultaneously affected by a number of environmental variables. For example, correlations between leaf water potential and either flux of radiant energy or vapour pressure deficit show a diurnal hysteresis which leads to a scatter diagram if many values are plotted. However, a simple model may be adequate to relate leaf water potential to the flow of water through the plant. The stomatal conductance of illuminated leaves is a function of current levels of temperature, vapour pressure deficit, leaf water potential (really turgor pressure) and ambient CO 2 concentration. Consequently, when plotted against any one of these variables a scatter diagram results. Physiological knowledge of stomatal functioning is not adequate to provide a mechanistic model linking stomatal conductance to all these variables. None the less, the parameters describing the relationships with the variables can be conveniently estimated from field data by a technique of non-linear least squares, for predictive purposes and to describe variations in response from season to season and plant to plant.

scholarly journals Effect of different soil water potential on leaf transpiration and on stomatal conductance in poinsettia

2013 ◽  
Vol 55 (2) ◽  
pp. 27-36
Author(s):  
Jacek S. Nowak
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Moisture Stress ◽  
Growing Period ◽  
High Soil Moisture ◽  
Cultivation Period ◽  
Leaf Transpiration

<i>Euphorbia pulcherrima</i> Wild.'Lilo' was grown in containers in 60% peat, 30% perlite and 10% clay (v/v) mixture, with different irrigation treatments based on soil water potential. Plants were watered at two levels of drought stress: -50kPa or wilting. The treatments were applied at different stages of plant development for a month or soil was brought to the moisture stress only twice. Additionally, some plants were watered at -50 kPa during the entire cultivation period while the control plants were watered at -5kPa. Plants were also kept at maximum possible moisture level (watering at -0,5kPa) or close to it (-1.OkPa) through the entire growing period. Soil water potential was measured with tensiometer. Drought stress applied during entire cultivation period or during the flushing stage caused significant reduction in transpiration and conductance of leaves. Stress applied during bract coloration stage had not as great effect on the stomatal conductance and transpiration of leaves as the similar stress applied during the flushing stage. High soil moisture increased stomatal conductance and transpiration rate, respectively by 130% and 52% (flushing stage), and 72% and 150% (bract coloration stage) at maximum, compared to the control.

scholarly journals Using MODIS derived <i>f</i>PAR with ground based flux tower measurements to derive the light use efficiency for two Canadian peatlands

2008 ◽  
Vol 5 (2) ◽  
pp. 1765-1794 ◽  
Author(s):  
J. Connolly ◽  
N. T. Roulet ◽  
J. W. Seaquist ◽  
N. M. Holden ◽  
P. M. Lafleur ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Photosynthetically Active Radiation ◽  
Vapour Pressure Deficit ◽  
Remote Sensing Data ◽  
Limiting Factor ◽  
Light Use Efficiency ◽  
Active Radiation ◽  
Flux Tower ◽  
Use Efficiency ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. We used satellite remote sensing data; fraction of photosynthetically active radiation absorbed by vegetation (fPAR) from the Moderate Resolution Imaging Spectroradiometer (MODIS) in combination with tower eddy covariance and meteorological measurements to characterise the light use efficiency parameter (ε) variability and the maximum ε (εmax) for two contrasting Canadian peatlands. Eight-day MODIS fPAR data were acquired for the Mer Bleue (2000 to 2003) and Western Peatland (2004). Flux tower eddy covariance and meteorological measurements were integrated to the same eight-day time stamps as the MODIS fPAR data. A light use efficiency model: GPP=ε * APAR (where GPP is Gross Primary Productivity and APAR is absorbed photosynthetically active radiation) was used to calculated ε. The εmax value for each year (2000 to 2003) at the Mer Bleue bog ranged from 0.58 g C MJ−1 to 0.78 g C MJ−1 and was 0.91 g C MJ−1 in 2004, for the Western Peatland. The average growing season ε for the Mer Bleue bog for the four year period was 0.35 g C MJ−1 and for the Western Peatland in 2004 was 0.57 g C MJ−1. The average snow free period ε for the Mer Bleue bog over the four year period was 0.27 g C MJ−1 and for the Western Peatland in 2004 was 0.39 g C MJ−1. Using the light use efficiency method we calculated the εmax and the annual variability in ε for two Canadian peatlands. We determined that temperature was a growth-limiting factor at both sites Vapour Pressure Deficit (VPD) however was not. MODIS fPAR is a useful tool for the characterization of ε at flux tower sites.

scholarly journals Towards a unified theory of plant photosynthesis and hydraulics

2020 ◽  
Author(s):  
Jaideep Joshi ◽  
Ulf Dieckmann ◽  
Iain Colin Prentice
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
Plant Responses ◽  
Plant Hydraulics ◽  
Plant Photosynthesis ◽  
Embolism Resistance

&lt;p&gt;Increasing frequencies and intensities of droughts are projected for many regions of the Earth. Water stress leads to a decline in the gross primary productivity (GPP) of plants. Plant responses to water stress vary with timescale, and plants adapted to different environments differ in their responses. Here, we present a unified theory of plant photosynthesis and plant hydraulics, which explains a wide range of observed plant responses to developing water stress.&lt;/p&gt;&lt;p&gt;Our theory is based on the least-cost hypothesis of Prentice et al. (2014). By integrating plant hydraulics into the least-cost framework, we attempt to improve upon the model of GPP by Wang et al. (2017), which accurately predicts the responses of global GPP to temperature, elevation, and vapour pressure deficit, but overestimates GPP under water-stressed conditions. Our model has three key ingredients. (1) The aforementioned least-cost framework, in which optimal stomatal conductance minimizes the summed costs of maintaining transpiration, the photosynthetic machinery, and the hydraulic pathways, including the potential costs of repairing embolized xylem. We also test a closely related maximum-benefit framework, in which optimal stomatal conductance maximizes the net benefit from assimilation while accounting for these summed costs, and obtain comparable results. (2) A trait-dependent model of water flow through the plant stem, in which water flow is limited by the conductivity (K&lt;sub&gt;s&lt;/sub&gt;) and embolism resistance (P&lt;sub&gt;50&lt;/sub&gt;) of the hydraulic pathway. At the shortest timescale, water stress causes stomatal closure to an extent that the transpiration demand determined by the vapour pressure deficit at the leaf surface is matched by the water supply through the stem. (3) A short-term response of photosynthetic capacity (V&lt;sub&gt;cmax&lt;/sub&gt;) to soil moisture, through which the potential V&lt;sub&gt;cmax&lt;/sub&gt; acclimates to prevailing daytime conditions to equalize carboxylation-limited and electron-transport-limited photosynthesis rates (A&lt;sub&gt;c&lt;/sub&gt; and A&lt;sub&gt;j&lt;/sub&gt;), while the realized values of V&lt;sub&gt;cmax&lt;/sub&gt;, A&lt;sub&gt;c&lt;/sub&gt;, and A&lt;sub&gt;j&lt;/sub&gt; are reduced from their potential values by a factor dependent on the leaf water potential and the leaf embolism resistance.&lt;/p&gt;&lt;p&gt;We estimate the parameters of our model using published data from short-term and long-term dry-down experiments. The key predictions of our model are as follows: (1) GPP declines with decreasing soil water potential and drops to zero soon after the soil water potential crosses P&lt;sub&gt;50&lt;/sub&gt;; (2) soil-to-leaf water potential difference remains relatively constant under developing water stress; (3) functional forms describing the declines in stomatal conductance, V&lt;sub&gt;cmax&lt;/sub&gt;, and GPP with soil water potential are consistent with observations; and (4) decreased photosynthetic capacity (V&lt;sub&gt;cmax&lt;/sub&gt;) recovers (in the long term) if the plant increases its Huber value (e.g., by shedding leaves), increases its conductivity (e.g., by growing wider new vessels), or decreases its height growth (e.g., by reducing allocation to growth). Our theory provides a potential way of integrating trait-based responses of plants to water stress into global vegetation models, and should therefore help to improve predictions of the global carbon and water cycles in a changing environment.&lt;/p&gt;&lt;p&gt;References: [1] Prentice IC, et al. &lt;em&gt;Ecology letters&lt;/em&gt; 17.1 (2014): 82-91.&amp;#160; [2] Wang H, et al. &lt;em&gt;Nature Plants&lt;/em&gt; 3.9 (2017): 734.&lt;/p&gt;

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