Hyperspectral and Thermal Sensing of Stomatal Conductance, Transpiration, and Photosynthesis for Soybean and Maize under Drought

During water stress, crops undertake adjustments in functional, structural, and biochemical traits. Hyperspectral data and machine learning techniques (PLS-R) can be used to assess water stress responses in plant physiology. In this study, we investigated the potential of hyperspectral optical (VNIR) measurements supplemented with thermal remote sensing and canopy height (hc) to detect changes in leaf physiology of soybean (C3) and maize (C4) plants under three levels of soil moisture in controlled environmental conditions. We measured canopy evapotranspiration (ET), leaf transpiration (Tr), leaf stomatal conductance (gs), leaf photosynthesis (A), leaf chlorophyll content and morphological properties (hc and LAI), as well as vegetation cover reflectance and radiometric temperature (TL,Rad). Our results showed that water stress caused significant ET decreases in both crops. This reduction was linked to tighter stomatal control for soybean plants, whereas LAI changes were the primary control on maize ET. Spectral vegetation indices (VIs) and TL,Rad were able to track these different responses to drought, but only after controlling for confounding changes in phenology. PLS-R modeling of gs, Tr, and A using hyperspectral data was more accurate when pooling data from both crops together rather than individually. Nonetheless, separated PLS-R crop models are useful to identify the most relevant variables in each crop such as TL,Rad for soybean and hc for maize under our experimental conditions. Interestingly, the most important spectral bands sensitive to drought, derived from PLS-R analysis, were not exactly centered at the same wavelengths of the studied VIs sensitive to drought, highlighting the benefit of having contiguous narrow spectral bands to predict leaf physiology and suggesting different wavelength combinations based on crop type. Our results are only a first but a promising step towards larger scale remote sensing applications (e.g., airborne and satellite). PLS-R estimates of leaf physiology could help to parameterize canopy level GPP or ET models and to identify different photosynthetic paths or the degree of stomatal closure in response to drought.

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Interactions between leaf water potential, stomatal conductance and abscisic acid content of orange trees submitted to drought stress

Brazilian Journal of Plant Physiology ◽

10.1590/s1677-04202004000300005 ◽

2004 ◽

Vol 16 (3) ◽

pp. 155-161 ◽

Cited By ~ 38

Author(s):

Mara de Menezes de Assis Gomes ◽

Ana Maria Magalhães Andrade Lagôa ◽

Camilo Lázaro Medina ◽

Eduardo Caruso Machado ◽

Marcos Antônio Machado

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Stomatal Conductance ◽

Water Potential ◽

Leaf Water Potential ◽

Acid Content ◽

Stomatal Closure ◽

Leaf Water ◽

Orange Trees ◽

Abscisic Acid Content

Thirty-month-old 'Pêra' orange trees grafted on 'Rangpur' lemon trees grown in 100 L pots were submitted to water stress by the suspension of irrigation. CO2 assimilation (A), transpiration (E) and stomatal conductance (g s) values declined from the seventh day of stress, although the leaf water potential at 6:00 a.m. (psipd) and at 2:00 p.m. (psi2) began to decline from the fifth day of water deficiency. The CO2 intercellular concentration (Ci) of water-stressed plants increased from the seventh day, reaching a maximum concentration on the day of most severe stress. The carboxylation efficiency, as revealed by the ratio A/Ci was low on this day and did not show the same values of non-stressed plants even after ten days of rewatering. After five days of rewatering only psi pd and psi2 were similar to control plants while A, E and g s were still different. When psi2 decreases, there was a trend for increasing abscisic acid (ABA) concentration in the leaves. Similarly, stomatal conductance was found to decrease as a function of decreasing psi2. ABA accumulation and stomatal closure occurred when psi2 was lower than -1.0 MPa. Water stress in 'Pera´ orange trees increased abscisic acid content with consequent stomatal closure and decreased psi2 values.

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Thermal Infrared Hyperspectral Imaging for Mineralogy Mapping of a Mine Face

Remote Sensing ◽

10.3390/rs10101518 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1518 ◽

Cited By ~ 3

Author(s):

Stephane Boubanga-Tombet ◽

Alexandrine Huot ◽

Iwan Vitins ◽

Stefan Heuberger ◽

Christophe Veuve ◽

...

Keyword(s):

Remote Sensing ◽

Spectral Resolution ◽

Remote Sensing Data ◽

Field Measurements ◽

Thermal Infrared ◽

Field Studies ◽

Hyperspectral Data ◽

Spectral Bands ◽

Remote Sensing Systems ◽

Viewing Perspective

Remote sensing systems are largely used in geology for regional mapping of mineralogy and lithology mainly from airborne or spaceborne platforms. Earth observers such as Landsat, ASTER or SPOT are equipped with multispectral sensors, but suffer from relatively poor spectral resolution. By comparison, the existing airborne and spaceborne hyperspectral systems are capable of acquiring imagery from relatively narrow spectral bands, beneficial for detailed analysis of geological remote sensing data. However, for vertical exposures, those platforms are inadequate options since their poor spatial resolutions (metres to tens of metres) and NADIR viewing perspective are unsuitable for detailed field studies. Here, we have demonstrated that field-based approaches that incorporate thermal infrared hyperspectral technology with about a 40-nm bandwidth spectral resolution and tens of centimetres of spatial resolution allow for efficient mapping of the mineralogy and lithology of vertical cliff sections. We used the Telops lightweight and compact passive thermal infrared hyperspectral research instrument for field measurements in the Jura Cement carbonate quarry, Switzerland. The obtained hyperspectral data were analysed using temperature emissivity separation algorithms to isolate the different contributions of self-emission and reflection associated with different carbonate minerals. The mineralogical maps derived from measurements were found to be consistent with the expected carbonate results of the quarry mineralogy. Our proposed approach highlights the benefits of this type of field-based lightweight hyperspectral instruments for routine field applications such as in mining, engineering, forestry or archaeology.

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Down-regulation of photosynthesis by drought under field conditions in grapevine leaves

Functional Plant Biology ◽

10.1071/pp98054 ◽

1998 ◽

Vol 25 (8) ◽

pp. 893 ◽

Cited By ~ 59

Author(s):

J. Flexas ◽

J. M. Escalona ◽

H. Medrano

Keyword(s):

Water Stress ◽

Electron Transport ◽

Stomatal Conductance ◽

Stomatal Closure ◽

General Pattern ◽

Photochemical Reactions ◽

Field Conditions ◽

Down Regulation ◽

Potted Plants ◽

Intrinsic Water Use Efficiency

The importance of both stomatal closure and reduced carboxylation efficiency on the photo- synthesis decline in response to long term water stress was previously measured in field-grown grapevines. Here we address the question of whether water stress affects the photochemical capacity of leaves, measuring gas-exchange rates and chlorophyll fluorescence under drought and moderate irrigat- ion at intervals through the summer season during three consecutive years. We conclude that usually water stress does not induce photoinhibition in field-grown grapevines, even when stomatal conductance and photosynthesis are reduced to very low values. Moreover, down-regulat- ion of photochemical reactions is low, leading to a general pattern of photosynthetic response to drought consistent in large reductions of stomatal conductance (g), followed by a consistent decrease of CO2 assimilation (A) but with a much lower effect on electron transport rate (ETR). In consequence, the intrinsic water-use efficiency (A/g) increased, as well as the ratio ETR/A. It is suggested that increased electron transport to alternative pathways, such as photorespiration, prevented further down-regulation of ETR under drought conditions. These results are in agreement with our previous reports for potted plants. However it is clear that, under field conditions with a much more slowly developed water stress, ETR reductions are more attenuated than in potted plants, reducing their incidence in carbon assimilation, which seems to be mainly regulated by stomatal closure.

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Effect of Water Stress on Stomatal Conductance and Leaf Water Relations of Leaves Along Current-Year Branches of Peach

Functional Plant Biology ◽

10.1071/pp9890549 ◽

1989 ◽

Vol 16 (6) ◽

pp. 549 ◽

Cited By ~ 4

Author(s):

SL Steinberg ◽

MJ Mcfarland ◽

JC Miller

Keyword(s):

Water Stress ◽

Stomatal Conductance ◽

Water Potential ◽

Water Status ◽

Stomatal Closure ◽

Water Flux ◽

Leaf Water ◽

Leaf Water Status ◽

Mature Leaves ◽

Water Potentials

A gradation, that reflects the maturity of the leaves, exists in the leaf water, osmotic and turgor potential and stomatal conductance of leaves along current and 1-year-old branches of peach. Predawn leaf water potentials of immature folded leaves were approximately 0.24 MPa lower than mature leaves under both well-watered and dry conditions. During the daytime the leaf water potential of immature leaves reflected the water potential produced by water flux for transpiration. In well- watered trees, mature and immature unfolded leaves had a solute potential at least 0.5 MPa lower than immature folded leaves, resulting in a turgor potential that was approximately 0.8 MPa higher. The turgor requirement for growth appeared to be much less than that maintained in mature leaves. As water stress developed and leaf water potentials decreased, the osmotic potential of immature folded leaves declined to the level found in mature leaves, thus maintaining turgor. In contrast, mature leaves showed little evidence of turgor maintenance. Stomatal conductance was lower in immature leaves than in fully mature leaves. With the onset of water stress, conductance of mature leaves declined to a level near that of immature leaves. Loss of turgor in mature leaves may be a major factor in early stomatal closure. It was concluded that osmotic adjustment played a role in maintenance of a leaf water status favorable for some growth in water-stressed immature peach leaves.

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A Systematic Review of Hardware-Accelerated Compression of Remotely Sensed Hyperspectral Images

Sensors ◽

10.3390/s22010263 ◽

2021 ◽

Vol 22 (1) ◽

pp. 263

Author(s):

Amal Altamimi ◽

Belgacem Ben Ben Youssef

Keyword(s):

Remote Sensing ◽

Systematic Review ◽

Hyperspectral Image ◽

Hyperspectral Data ◽

Hyperspectral Images ◽

Sensor Technology ◽

Future Research ◽

Sensing Applications ◽

Remote Sensing Applications ◽

The Impact

Hyperspectral imaging is an indispensable technology for many remote sensing applications, yet expensive in terms of computing resources. It requires significant processing power and large storage due to the immense size of hyperspectral data, especially in the aftermath of the recent advancements in sensor technology. Issues pertaining to bandwidth limitation also arise when seeking to transfer such data from airborne satellites to ground stations for postprocessing. This is particularly crucial for small satellite applications where the platform is confined to limited power, weight, and storage capacity. The availability of onboard data compression would help alleviate the impact of these issues while preserving the information contained in the hyperspectral image. We present herein a systematic review of hardware-accelerated compression of hyperspectral images targeting remote sensing applications. We reviewed a total of 101 papers published from 2000 to 2021. We present a comparative performance analysis of the synthesized results with an emphasis on metrics like power requirement, throughput, and compression ratio. Furthermore, we rank the best algorithms based on efficiency and elaborate on the major factors impacting the performance of hardware-accelerated compression. We conclude by highlighting some of the research gaps in the literature and recommend potential areas of future research.

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Effect of Water Stress during Grain Filling on Yield, Quality and Physiological Traits of Illpa and Rainbow Quinoa (Chenopodium quinoa Willd.) Cultivars

Plants ◽

10.3390/plants8060173 ◽

2019 ◽

Vol 8 (6) ◽

pp. 173 ◽

Cited By ~ 2

Author(s):

Angie L. Gámez ◽

David Soba ◽

Ángel M. Zamarreño ◽

José M. García-Mina ◽

Iker Aranjuelo ◽

...

Keyword(s):

Water Stress ◽

Stomatal Conductance ◽

Water Deficit ◽

Stomatal Closure ◽

Chenopodium Quinoa ◽

Grain Filling ◽

Quality Parameters ◽

Stomatal Opening ◽

Climate Change Scenarios ◽

Yield And Quality

The total area under quinoa (Chenopodium quinoa Willd.) cultivation and the consumption of its grain have increased in recent years because of its nutritional properties and ability to grow under adverse conditions, such as drought. Climate change scenarios predict extended periods of drought and this has emphasized the need for new crops that are tolerant to these conditions. The main goal of this work was to evaluate crop yield and quality parameters and to characterize the physiology of two varieties of quinoa grown under water deficit in greenhouse conditions. Two varieties of quinoa from the Chilean coast (Rainbow) and altiplano (Illpa) were used, grown under full irrigation or two different levels of water deficit applied during the grain filling period. There were no marked differences in yield and quality parameters between treatments, but the root biomass was higher in plants grown under severe water deficit conditions compared to control. Photosynthesis, transpiration and stomatal conductance decreased with increased water stress in both cultivars, but the coastal variety showed higher water use efficiency and less discrimination of 13C under water deficit. This response was associated with greater root development and a better stomatal opening adjustment, especially in the case of Rainbow. The capacity of Rainbow to increase its osmoregulant content (compounds such as proline, glutamine, glutamate, K and Na) could enable a potential osmotic adjustment in this variety. Moreover, the lower stomatal opening and transpiration rates were also associated with higher leaf ABA concentration values detected in Rainbow. We found negative logarithmic relationships between stomatal conductance and leaf ABA concentration in both varieties, with significant R2 values of 0.50 and 0.22 in Rainbow and Illpa, respectively. These moderate-to-medium values suggest that, in addition to ABA signaling, other causes for stomatal closure in quinoa under drought such as hydraulic regulation may play a role. In conclusion, this work showed that two quinoa cultivars use different strategies in the face of water deficit stress, and these prevent decreases in grain yield and quality under drought conditions.

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Shoot Characterization of Isoprene and Ocimene-Emitting Transgenic Arabidopsis Plants under Contrasting Environmental Conditions

Plants ◽

10.3390/plants9040477 ◽

2020 ◽

Vol 9 (4) ◽

pp. 477 ◽

Cited By ~ 2

Author(s):

Michele Faralli ◽

Mingai Li ◽

Claudio Varotto

Keyword(s):

Water Stress ◽

Stress Tolerance ◽

Stress Responses ◽

Water Conservation ◽

Transgenic Arabidopsis ◽

Stomatal Closure ◽

Crop Improvement ◽

Dry Weight ◽

Co2 Assimilation ◽

Biotic And Abiotic Stress

Isoprenoids are among the most abundant biogenic volatile compounds (VOCs) emitted by plants, and mediate both biotic and abiotic stress responses. Here, we provide for the first time a comparative analysis of transgenic Arabidopsis lines constitutively emitting isoprene and ocimene. Transgenic lines and Columbia-0 (Col-0) Arabidopsis were characterized under optimal, water stress, and heat stress conditions. Under optimal conditions, the projected leaf area (PLA), relative growth rate, and final dry weight were generally higher in transgenics than Col-0. These traits were associated to a larger photosynthetic capacity and CO2 assimilation rate at saturating light. Isoprene and ocimene emitters displayed a moderately higher stress tolerance than Col-0, showing higher PLA and gas-exchange traits throughout the experiments. Contrasting behaviors were recorded for the two overexpressors under water stress, with isoprene emitters showing earlier stomatal closure (conservative behavior) than ocimene emitters (non-conservative behavior), which might suggest different induced strategies for water conservation and stress adaptation. Our work indicates that (i) isoprene and ocimene emitters resulted in enhanced PLA and biomass under optimal and control conditions and that (ii) a moderate stress tolerance is induced when isoprene and ocimene are constitutively emitted in Arabidopsis, thus providing evidence of their role as a potential preferable trait for crop improvement.

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GYROCOPTER-BASED REMOTE SENSING PLATFORM

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-7-w3-1333-2015 ◽

2015 ◽

Vol XL-7/W3 ◽

pp. 1333-1337 ◽

Cited By ~ 1

Author(s):

I. Weber ◽

A. Jenal ◽

C. Kneer ◽

J. Bongartz

Keyword(s):

Remote Sensing ◽

High Resolution ◽

Imaging System ◽

Infrared Range ◽

Spectral Bands ◽

Sensing Applications ◽

Sensing Platform ◽

Sensor Configuration ◽

Flexible Imaging ◽

Thermal Imaging System

In this paper the development of a lightweight and highly modularized airborne sensor platform for remote sensing applications utilizing a gyrocopter as a carrier platform is described. The current sensor configuration consists of a high resolution DSLR camera for VIS-RGB recordings. As a second sensor modality, a snapshot hyperspectral camera was integrated in the aircraft. Moreover a custom-developed thermal imaging system composed of a VIS-PAN camera and a LWIR-camera is used for aerial recordings in the thermal infrared range. Furthermore another custom-developed highly flexible imaging system for high resolution multispectral image acquisition with up to six spectral bands in the VIS-NIR range is presented. The performance of the overall system was tested during several flights with all sensor modalities and the precalculated demands with respect to spatial resolution and reliability were validated. The collected data sets were georeferenced, georectified, orthorectified and then stitched to mosaics.

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THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCOA (THEOBROMA CACAO L.): A REVIEW

Experimental Agriculture ◽

10.1017/s0014479711000421 ◽

2011 ◽

Vol 47 (4) ◽

pp. 653-676 ◽

Cited By ~ 52

Author(s):

M. K. V. CARR ◽

G. LOCKWOOD

Keyword(s):

Water Stress ◽

Stomatal Conductance ◽

Water Use ◽

Water Relations ◽

Stomatal Closure ◽

Dry Season ◽

Leaf Water ◽

Background Information ◽

Published Data ◽

Rhythmic Pattern

SUMMARYThe results of research into the water relations of cocoa are reviewed in the context of drought mitigation and irrigation need. Background information on the centres of production of the cocoa tree, and the role of water in crop development and growth processes, is followed by reviews of the effects of water stress on stomatal conductance, leaf water status and gas exchange, together with drought tolerance, crop water use and water productivity. Leaf and shoot growth occur in a series of flushes, which are synchronized by the start of the rains following a dry season (or an increase in temperature), alternating with periods of ‘dormancy’. Flowering is inhibited by water stress but synchronous flowering occurs soon after the dry season ends. Roots too grow in a rhythmic pattern similar to that of leaf flushes. Roots can reach depths of 1.5–2.0 m, but with a mass of roots in the top 0.2–0.4 m, and spread laterally >5 m from the stem. Stomata open in low light intensities and remain fully open in full sunlight in well-watered plants. Partial stomatal closure begins at a leaf water potential of about −1.5 MPa. Stomatal conductance is sensitive to dry air, declining as the saturation deficit increases from about 1.0 up to 3.5 kPa. Net photosynthesis and transpiration both consequently decline over a similar range of values. Little has been published on the actual water use of cocoa in the field. Measured ETc values equate to <2 mm d−1 only, whereas computed ETc rates of 3–6 mm d−1 in the rains and <2 mm d−1 in the dry season have also been reported. Despite its sensitivity to water stress, there is too a paucity of reliable, field-based published data of practical value on the yield responses of cocoa to drought or to irrigation. With the threat of climate change leading to less, or more erratic, rainfall in the tropics, uncertainty in yield forecasting as a result of water stress will increase. Social, technical and economic issues influencing the research agenda are discussed.

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Illumination-Independent Reflectance Information Acquirement for Leaf Water Potential Measurement on the Example of Satsuma Mandarin

International Journal of Horticultural Science ◽

10.31421/ijhs/9/3-4/409 ◽

2003 ◽

Vol 9 (3-4) ◽

Author(s):

J. Kriston-Vizi ◽

M. Umeda ◽

K. Miyamoto ◽

A. Ferenczy

Keyword(s):

Remote Sensing ◽

Water Stress ◽

Water Potential ◽

Leaf Water Potential ◽

Visual Information ◽

Leaf Water ◽

Sugar Accumulation ◽

Potential Measurement ◽

Satsuma Mandarin ◽

Sensing Applications

Mandarin fruit sugar content can be increased when subjecting the satsuma mandarin tree (Citrus unshiu MARC. var. satsuma) to moderate water stress by mulching during the period of active sugar accumulation, thereby fruit quality improvement can be realized. In the frame of the precision agriculture production system, a non-destructive measuring method development became necessary based on remote sensing, field spectroscopy and image analysis, to be able to measure the degree of water stress. Large amount of visual information have been recorded at ground level, in near infrared, red and green channels by a false color digital camcorder designed specially for remote sensing applications. A method have been found to be able to calculate the absolute reflection of mandarin leaf surface by comparing leaf reflectance with known reference target reflectance, thereby established the basis of further studies in this topic. Leaf absolute reflection can be measured reliably, under variable natural illumination at field conditions. Functional correlation can be searched between visual information and leaf water potential measured by PMS pressure chamber.

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