2,298 research outputs found
Estimating Crop Stomatal Conductance Through High-Throughput Plant Phenotyping
During photosynthesis and transpiration, crops exchange carbon dioxide and water with the atmosphere through stomata. When a crop experiences water stress, stomata are closed to reducing water loss. However, the closing of stomata also negatively affects the photosynthetic efficiency of the crop and leads to lower yields. Stomatal conductance (gs) quantifies the degree of stomatal opening and closing by using the rate of gas exchange between the crop and the atmosphere, which helps to understand the water status of the crop for better irrigation management. Unfortunately, gs measurement typically requires contact measuring instruments and manual collection in the field, which is time-consuming and labor-intensive. Thus, this study estimates gs in two ways. Firstly, plant phenotypic data and weather information were used to estimate gs for various types of crops. The plant phenotypic data were extracted from images captured by a thermal infrared camera, a multispectral camera, and a visible and near-infrared spectrometer integrated on field phenotyping platform. Weather information was obtained from a field weather station. The random forest regression (RFR) model performed the best with R2 of 0.69 and RMSE of 0.135 mol*m-2 *s-1 , while the model using weather parameters alone had R2 of 0.58 and RMSE of 0.161, and the model using phenotypic data alone had R2 values of 0.59 and RMSE of 0.158 mol*m-2 *s-1 . The results indicated that there was a complementary relationship between plant phenotypic data and weather information in estimating gs. The second aspect of the study was to estimate maize and soybean gs directly from near-infrared, thermal-infrared and RGB (Red Green Blue) images collected by the same platform. The results showed that the convolutional neural network (CNN) model outperformed the other models with an R2 of 0.52. In addition, adding soil moisture as a variable to the model improved its accuracy, which decreased the RMSE from 0.147 to 0.137 mol*m-2 *s-1 . This study highlights the potential of estimating gs from remote sensing and field phenotyping platforms to help growers obtain information about the water status of crops and plan irrigation more efficiently.
Advisor: Yufeng G
Predicting Transpiration Rates of Hydroponically-Grown Plant Communities in Controlled Environments
Canopy transpiration is a major factor determining crop evapotranspiration and energy budgets. Unfortunately the development of robust models of canopy transpiration is hindered by a lack of reliable data due to the difficulties of making canopy-scale measurements. However, measurements of canopy water vapor and carbon fluxes via gas exchange techniques are possible in controlled environments. Simultaneous measurements of transpiration, photosynthesis, and canopy temperature were made in wheat and soybean communities. These data were used to calculate chamber aerodynamic and canopy stomata! conductances, and to model the response of canopy transpiration to CO2concentration and vapor pressure deficit. Canopy stomata! conductance was found to decrease diurnally by 20-30% in well-watered crops grown under constant environmental conditions. The magnitude of this diurnal decrease in the canopy stomata! conductance of wheat and soybean decreased with increasing ambient CO2 concentrations. Eight models describing how canopy stomatal conductance responds to environmental changes were incorporated into a canopy transpiration model. The results and methods developed in this study will allow future physiologically-based canopy transpiration models to incorporate these models for predicting the response of transpiration rates in controlled environments
Characterization of plant water flows in Controlled environment -PLANT SMART SENSORS
The present thesis project "Characterization of water flows in Controlled Environment -PLANT
SMART SENSORS" has a multidisciplinary core and aimed towards the creation of synergies
between the world of scientific research and the industry. By applying research results to
technological development, this research targeted at innovation in the Agrotechnology and
Aerospace sectors. Indeed, the introduction of new technologies is pivotal for controlled environment
production on Earth to feed a growing population as well as for human permanence in Space in longterm missions where plants are used to regenerate resources (e.g. oxygen, water) and as source of
fresh high-nutritious food. The realization of these systems must be based on a precise knowledge
of plant morpho-anatomical development and its physiological behavior in closed growth systems,
which are strongly influenced by numerous environmental factors including the relative humidity or
more specifically the Vapour Pressure Deficit (VPD). In a protected environment (e.g. in Space
greenhouses, vertical farm, indoor growing-modules), the control of relative humidity represents a
significant problem, which has often been neglected. For instance, in conditions of poor aeration, too
high humidity can occur with consequent low values of VPD which reduces the plant transpiration,
slowing or stopping the water flow through the SPAC (Soil-plant-atmosphere-continuum), and
ultimately blocking the photosynthesis, yield and biomass production.
Even though there have been many studies regarding the VPD control, alone and/or in combination
with other environmental factors, certain points are still unclear or controversial, providing contrasting
results in different or even in the same species. This happens mainly due to the complex interactions
between many microclimatic factors and plant physiological behaviour at different phenological
stages.
In a context of climate change, the efficient regulation of VPD can be applied to greenhouse and
indoor-module production in order to enhance crop productivity, improve WUE and reduce total water
consumption to design irrigation strategies, considering the balance between the amount of water
saved and the quantity used to regulate the VPD.
The regulation of the VPD and related environmental parameters need to be designed according to
the species and its adaptive plasticity at morphophysiological levels.  Thus, the characterization and
modeling of water flows in model plants in different growth chamber scenarios (from small modules
intended for the spatialization for Space applications, up to structures that can be used in protected
cultivation on Earth), as well as the real-time monitoring of the water status of plants, become
fundamental for the management of precision agriculture both in support of Space exploration and
for the sustainability of urban agriculture. To date, most of the research has focused on either specific
physiological/structural aspect at the single-plant level, or on cultivation management or even on
technological aspects, with only a few interlinks of knowledge.
The aim of this thesis is to develop knowledge to help filling this gap to improve the understanding
of VPD effects on crop productivity, with the creation of synergies among different expertise (e.g.,
plant physiology, crop science, engineering). To do so, it is fundamental to study the complexity of
plant morpho/physiological responses, since without a deep knowledge of mechanisms behind plant
responses to the environment it is difficult to determine how and to which extent plants can adapt to
any changes in the environmental conditions.
The application of a multidisciplinary approach in research will allow crop production in a sustainable
way, even in harsh environments, where a "climate smart-agriculture" becomes necessary to
improve crop yield and quality. The present thesis is organized as follows:
Chapter 1 is a review which presents the current state of knowledge on how VPD influences plant
morpho-physiological traits in controlled environment agriculture. The study has been published as
a review article in Annals of Applied Biology (Amitrano et al., 2019 https://doi.org/10.1111/aab.12544). It
covers main important aspects of VPD influence on plant growth, morpho-anatomical development,
and physiology, emphasizing the possible interaction between VPD and other microclimatic factors
in protected cultivation. Furthermore, the rewiew identifies and discusses future research areas,
which should be explored further, based on needed synergies among different expertise from
biological and horticultural fields.
Chapter 2 presents evidence that the modulation of relative humidity (RH) together with other
important cultivation factors such as light (presence/absence), can influence morpho-anatomical
development and improve antioxidant content, even at the early stages of plant life cycle
(germination, seedling establishment). The combined effect of RH and light was studied during the
germination and seedling development of Vigna radiata L. (mung bean), a species widespread
throughout the world also due to the high nutritional value of its edible sprouts. A manuscript reporting
these data has been published in Plants (Amitrano et al., 2020a https://doi.org/10.3390/plants9091093).
In Chapter 3, the role of leaf anatomical traits (e.g. leaf mesophyll features, stomata and vein traits)
in photosynthetic acclimation to short- and long-term changes in VPD was examined in Vigna radiata
L. adult plants. In this study, we underlined the key role of leaf structure
in photosynthetic acclimation to air VPD. The long-term exposure to different VPD levels determined
a pre-acclimation at the leaf morpho-anatomical level which influenced the extent of leaf
physiological plasticity, changing plant ability to acclimate to any changes in the surrounding
microclimate. This different leaf anatomy-related capacity of pre-acclimating becomes
therefore fundamental in the present climate-change scenario due to its key role in the adaptation
process under changing environmental conditions. A manuscript reporting these data has been
published in Environmental and Experimental Botany (Amitrano et al., 2021a
https://doi.org/10.1016/j.envexpbot.2021.104453).
In Chapter 4, the effect of VPD on morpho-physiological traits also incorporating the trade-off
between transpiration and carbon gain was evaluated in two cultivars of Salanova lettuce (Lactuca
sativa L.) with green and red leaves, in a growth-chamber experiment. Low-VPD turned
out to significantly improve growth, stomata development and hydraulic-related traits which led to
higher photosynthesis and a reduced water consumption compared to the high-VPD condition. A
manuscript reporting these data was published in Agronomy (Amitrano et al., 2021b
https://doi.org/10.3390/agronomy11071396). 
Chapter 5 represents a clear interlink of knowledge between plant scientists, engineers,
mathematician and modelists. In this study, published in Sensors (Amitrano et al., 2020b
https://doi.org/10.3390/s20113110), we used experimental data, based on morpho-anatomical analyses
of lettuce plants, to run the Energy Cascade Model (MEC), a model already used to predict biomass
production and photosynthetic efficiency in advanced life support systems studies (Space-oriented
research). Here, the modification of the model is discussed together with possible improvements and
applications.
Chapter 6 focuses on how to modulate the micro-environment, and in particular the VPD levels, in
protected cultivation to improve plant antioxidant content in crops. More specifically, the exposure of
the same lettuce cultivars mentioned in previous chapters to high VPD determined an improved
phytochemical content in lettuce leaves, especially in the red cultivar. Here we discussed a further
possibility to use short-term high VPD treatments as a mild stress to boost the phytochemical
production in lettuce plants. A Manuscript reporting these data has been published in Horticulturae
(Amitrano et al., 2021c http://doi.org/10.3390/horticulturae7020032).
Chapter 7 is a deep focus on how the VPD drives the coordination among morpho-anatomical traits
in leaves of the above-mentioned lettuce cultivars, also exploring the variability of traits along the
leaf lamina. More specifically, the attention is focused on how stomata and vein develop within
lettuce leaves and how these traits are coordinated with leaf size under different VPDs. Results from
this study suggest that VPD triggers a different response in lettuce plants in terms of balance of leaf
4
traits and highlight the possibility of further exploring the microenvironment (combined influence of
light and VPD) to adjust the development of stomata and vein densities, thus providing optimal water
and gas fluxes through the leaves.
In Chapter 8, the experiments conducted during the period spent at the Controlled Environment
Agriculture Center of the University of Arizona (UA-CEAC) are reported. The experiments reported
here were conducted on the same species of the previous chapters (Salanvoa lettuce with green
and red leaves) in a multi-layer vertical farm to test the interaction between VPD and other
microclimatic factors on plant morpho-physiological development. More specifically two experimental
trials are reported (E1 and E2). In E1, the interaction between VPD levels (low and high) and
increasing DLI (Daily Light Integral - 8.6, 12.9, 15.5) was tested to study morpho-physiological
changes and to determine the optimal combination of DLI and VPD for lettuce growth. In E2, a
sudden salt stress was applied to the cultivation and then CO2 enrichment was provided, based on
the hypothesis that the CO2 enrichment would mitigate the salt stress, modifying the plant carbon
gain/water balance. We evaluated whether the mechanisms of salt stress mitigation due to CO2
enrichment were different under high and low VPD conditions, depending on the different morphoanatomical leaf structure.  
Chapter 9 reports on experiments conducted at the IPK-Leibniz institute of plant genetics and crop
plant research (Gatersleeben, Germany) in the framework of the EPPN2020 transnational access
(https://eppn2020.plant-phenotyping.eu/EPPN_Transnational_Access). A report with obtained results is
showed in this chapter. These experiments concern the application of high-throughput phenotyping
combined with morpho-anatomical analyses on Salanova green and red plants acclimated to a VPD
level and then subjected to short-term changes in the VPD. The project submitted to the EPPN
transnational access and winner of the grant is presented in Appendix 1.
Chapter 10 and 11 report on the possible industrial applications after the collaboration with the
partner company "Kayser Italia srl" (http://www.kayser.it/). Chapter 10 is a study for the definition of
scientific and technical requirements for the realization of a miniaturized phenotyping growth
chamber to grow microgreens or small crops in Space. The structure of the chamber is based on the
"Kubik" incubator, an incubator facility of the European Space Agency with the shape of a cube of
about 40 cm that has been operating aboard the International Space Station for more than 12 years,
carrying different life science experiments. In the chapter, technical and scientific requirements are
listed and a preliminary schedule for the project realization is provided. At the end of the chapter,
open issues are also discussed. In Chapter 11, the set-up of a prototype miniaturized cultivation
chamber for use in Space is described and the results of validation tests, carried out at Kayser Italia
with brassica microgreens (Brassica rapa subsp. sylvestris var. esculenta) under different air relative
humidities (VPD), are reported.
In Appendix 1, the project submitted to the EPPN transnational access (PHEW- Automated
phenotyping platform to improve lettuce water use efficiency under different VPD and watering
regimens) and winner of the grant is presented.
In Appendix 2, a brief recap on the activities conducted during the Ph.D. program is presented
The effects of continuous lighting (CL) method on the growth development of brassica chinensis for led plant factory in wsn application
This study was performed to investigate the best practise on using LED light for optimum growth of Brassica Chinensis and reduce turn around time at different kind of photoperiod study utilizing Wireless Sensor Network (WSN) technology as remote monitoring system. Growth performance of Brassica Chinensis under two different wavelengths (blue and red) 16: 4 as light source has been used to determine plant growth performance and phytochemicals aspect of plant characteristics. Two experiments were conducted which is the pulse treatment (1 hour light and 1 hour dark) and continuous light (CL) photoperiod treatment in both trials. Observation such as leaves count, height, dry weight and chlorophy I & ll of both plants were analysed. It was noted that the CL photoperiod has significant effect on overall growth performance and remarkably lead to improve the efficiency of the plant factory. In order to reason on data and monitor the environmental parameters of the plant factory, an intelligent system using embedded system has been developed to automate the LED control and manipulation. The result shows that the system is stable and has referential significantly in the area of plant factory or indoor farming system
Fruit and Leaf Sensing for Continuous Detection of Nectarine Water Status
Continuous assessment of plant water status indicators might provide the most precise information for irrigation management and automation, as plants represent an interface between soil and atmosphere. This study investigates the relationship of plant water status to continuous fruit diameter (FD) and inverse leaf turgor pressure rates (pp) in nectarine trees [Prunus persica (L.) Batsch] throughout fruit development. The influence of deficit irrigation treatments on stem (Ψstem) and leaf water potential, leaf relative water content, leaf hydraulic conductance and fruit growth was studied across the stages of double-sigmoidal fruit development in 'September Bright' nectarines. Fruit relative growth rate (RGR) and leaf pressure change rate (RPCR) were derived from FD and pp to represent rates of water in- and outflows in the organs, respectively. Continuous RGR and RPCR dynamics were independently and combinedly related to plant water status and environmental variables. The independent use of RGR and RPCR yielded significant associations with midday Ψstem, the most representative index of tree water status in anisohydric species. However, the combined use of nocturnal fruit and leaf parameters unveiled an even more significant relationship with Ψstem, suggesting a different fruit-to-leaf water balance in response to pronounced water deficit. In conclusion, we highlight the suitability of a multi-organ sensing approach for improved prediction of tree water status
Assessment of plant water status variability by thermography: comparing ground measurements with remote imaging
Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de AgronomiaRemote sensing provides a fast alternative for traditional in situ water status measurement in vineyards. Canopy temperature measurements derived from aerial thermography were compared to thermal and plant physiological ground-truthing data of single vines in a low and high vigour zone. The experimental trial was carried out in a vineyard of Colli Piacentini, located in the province of Piacenza (Italy). Statistical methods were used to evaluate the correlation between acquired temperatures and plant physiological parameters. Results by simple regression showed significant correlation, with coefficient of determination (R2) higher than 0.6 for the indices studied; R2 higher than 0.7 for correlations of thermal data with vine water status' and R2 higher than 0.9 for correlations deriving from data of vines of the high vigour zone. These results propose that thermography is a good estimator for vine water status and photosynthetic activity. However, records of aerial and proximal thermal imaging are not congruent but have a similar behaviour and correlation when comparing to ground measurements. Therefore, when only using thermography, vine water stress is not only indicated by a higher canopy temperature in absolute values but is an implication of temperature variation within the field over time. Comparative measurements can improve assessing vine water status by observing changes in canopy temperatureN/
The effects of temperature on the photosynthesis and growth of crops
Imperial Users onl
Improved sapflow methodology reveals considerable night-time ozone uptake by Mediterranean species
Due to the evident tropospheric ozone impact on
plant productivity, an accurate ozone risk assessment for the
vegetation has become an issue. There is a growing evidence
that ozone stomatal uptake may also take place at night and
that the night-time uptake may be more damaging than diurnal
uptake. Estimation of night-time uptake in the field is
complicated because of instrumental difficulties. Eddy covariance
technology is not always reliable because of the
low turbulence at night. Leaf level porometry is defective
at relative humidity above 70% which often takes place at
night. Improved sap flow technology allows to estimate also
slow flows that usually take place at night and hence may
be, at present, the most trustworthy technology to measure
night-time transpiration and hence to derive canopy stomatal
conductance and ozone uptake at night. Based on micrometeorological
data and the sap flow of three Mediterranean
woody species, the night-time ozone uptake of these species
was evaluated during a summer season as drought increased.
Night-time ozone uptake was from 10% to 18% of the total
daily uptake when plants were exposed to a weak drought,
but increased up to 24% as the drought became more pronounced.
The percentage increase is due to a stronger reduction
of diurnal stomatal conductance than night-time stomatal
conductance
Automated Microwave Irrigation for Moisture Leve Control using Airblower System
Agriculture has been the most important practice from very beginning of the human civilization. It has seen many iterations of development in technology with time. A good agricultural practice is still an art. Environmental parameters such as soil moisture, temperature, humidity, pH, solar radiation ,etc. plays very important role in overall development of the plant. Temperature affects many of plant activities such as pollination, germination etc. It is observed that, at higher temperature, respiration rate increases that result in reduction of sugar contents of fruits and vegetables. At lower temperatures photosynthesis activity is slowed down . Humidity is responsible for moisture loss and temperature management of the plant. For high humid environment, evapotransmission will be less and more water will saturated in the leaf area. This results in enlargement and formation of fungus in the porous area of the leaf. Moisture is critical for seed germination and uptake of nutrients by the plant. Excess water may stop gaseous exchange between soil and the atmosphere which reduces root respiration and root growth. Optimum level of moisture ensures healthy growth of the root and overall development of the plant . A sustainable approach is required to maintain balance between these parameters and environment. Hence there is a need of efficient monitoring and control system. In recent engineering advances the convergence of internet, communication and information technologies paves the way for new generation. Currently, distributed wireless sensor network plays significant responsibility in civilizing agricultural production and mitigating the agony of farmers .Hence Here system has been developed to maintain balance between this parameter which are co-related .Basically system control the moisture level using air blower system and another advancement is that basic need of plant that is O2 and CO2 transmission to plant as per requirement
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