Ronald Maldonado Rodriguez - Academia.edu (original) (raw)

My scientific publications by Ronald Maldonado Rodriguez

Ciencia e Ingeniería, 2015

En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuron... more En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuronales artificiales para analizar señales de fluorescencia clorofílica (FC), con el fin de identificar y clasificar grupos de plantas de Vigna unguiculata (L.) Walp (fríjol) cultivadas en medios hidropónicos que contenían diferentes cantidades de nitrógeno (N) y las señales de fluorescencia de otro grupo de plantas cuyas semillas fueron inoculadas antes de su germinación con la bacteria Rhizobium variedad NGR232. Previo al entrenamiento neuronal se realizó un exhaustivo análisis estadístico multivariante, con la finalidad de detectar diferencias en los vectores de medias de los medios de cultivo y reducir el número de variables o puntos de las curvas de fluorescencia. El objetivo principal de este trabajo es desarrollar una herramienta para identificar la carencia de N en plantas de fríjol y otras leguminosas de mayor producción en agricultura.

Biointerface Research in Applied Chemistry, 2021

Pineapple (Ananas comosus (L.) Merril), one of the major fruit crops, is mainly used for raw cons... more Pineapple (Ananas comosus (L.) Merril), one of the major fruit crops, is mainly used for raw consumption and for industrial juice production, which creates large amounts of residues. The United Nations Food and Agriculture Organization (FAO) has estimated that pineapple waste accounts for between 50 to 65 % of the total weight of the fruit. Industrial pineapple waste is a major source of pollution as important quantities of primary residues are not further processed. Pineapple waste contains bioactive compounds such as carotenoids, polyphenols, fibers, vitamins, enzymes, and essential oils. These phytochemicals can be used in the food industry, medicine and pharmacy, textile, and others. This review highlights essential oil and other bioactive compounds extracted from pineapple waste and the composition of pineapple essential oil. Pineapple peels are the potential raw material for essential oil extraction through various methods. Modern spectrometric methods have shown that essentia...

Journal of Agronomy and Crop Science, 2021

Science Access, 2001

Chlorophyll a fluorescence is a useful and non-invasive tool to screen for the effects of many bi... more Chlorophyll a fluorescence is a useful and non-invasive tool to screen for the effects of many biotic and abiotic parameters on photosynthesis in plants. The fluorescence of leaves after light excitation was measured with a portable fluorimeter (Plant Efficiency Analyser, built by Hansatech Instruments King?s Lynn Norfolk, PE 30 4 NE, GB) and the subsequent data were analysed using the JIP-test which produces parameters indicating PSII and photosynthesis activity. Seeds of Vigna unguiculata were sterilised before germinating and planting in Magenta jars (used in hydroponics culture) with a nutrient solution without nitrate (B&D solution). Half of the plants were inoculated with Rhizobium sp. NGR234 (1019 bacteria/ 100 µl) at roots level. Each half was then further divided and treated with KNO3 to produce four treatments. During 6 weeks measurements of several hundred measurements of 2 seconds are made on the leaves of inoculated and control plants, with or without different nitrate ...

Science Access, 2001

The fast fluorescence rise O-J-I-P (Strasser et al. 1995; Strasser and Strasser 1995) was used to... more The fast fluorescence rise O-J-I-P (Strasser et al. 1995; Strasser and Strasser 1995) was used to monitor coral health trough the photosynthetic activity of their zooxanthellae. The advantage is that such type of measurements are non invasive and the sample is exposed to the experimental light only during a few seconds. We have provided coral with "quasi-natural" conditions : a sea water aquarium of 60 l with the polyps living on rocks close to the glass wall of the container. The temperature and salinity were kept constant, illumination was provided with three 18W reef aquarium neon, and one 18W blue neon lamps. Chlorophyll fluorescence was induced for 10 to 20 seconds every hour with a PEA-Instrument (Plant Efficiency Analyser built by Hansatech Instruments King?s Lynn Norfolk, PE 30 4 NE, GB) during several months. Different species of Anthozoa are being studied. Two species of Actinodiscus, and one unidentified (probably Madracis) freshly collected from Bali (Indonesia...

South African Journal of Botany, 2014

Due to chilling sensitivity, minimum night temperatures represent the main constraint in soybean ... more Due to chilling sensitivity, minimum night temperatures represent the main constraint in soybean production in South Africa. In vivo quantification of photosystem II (PSII) function by direct chlorophyll fluorescence revealed that dark chilling (8°) inhibited PSII function in the extreme chill sensitive genotype, Java 29 (JAs) mainly by deactivating reaction centers and inhibiting the conversion of excitation energy to electron transport and electron transfer from reduced plastoquinone to the PSI end electron acceptors. Further analysis of the normalized fast fluorescence transients, revealed that in JAs, upon dark chilling, disengagement of the oxygen evolution complex (ΔV K band) occurred which coincided with a concomitant decrease in O 2 evolution measured in vitro. The chilling resistant Maple Arrow (MAr), though one night cold stress lead to a decrease in fluorescence emission at 2 ms (−ΔV J band) indicating a decrease in the Q A − concentration due to cold-induced slowdown of electron donation from P 680 , however showed clear signs of recovery after the second and third cold nights. The moderate chill sensitive genotype, Fiskeby V (FBm) responded in a fashion intermediate to above-mentioned extremes. A second experiment showed that in JAs the inhibitory effect increased with increasing time of exposure to light following dark chilling. Our data demonstrated that significant differences exist in the cold tolerance of different soybean genotypes: (a) In respect to activity criteria, expressed by the quantum yields for primary photochemistry φ Po = TR o /ABS, for electron transport from photosystem II to photosystem I as φ Eo = ET o /ABS and the efficiency, φ Ro = RE o /ABS, to reduce the end electron acceptors of photosystem I up to NADP; (b) In respect to stability criteria, dependent on structure and conformation, such as the capability of energetic cooperativity (grouping) among photosynthetic units quantified by the grouping probability for exciton movements within the energetically connected group of entire photosynthetic units. Therefore analyzing the O-J-I-P fluorescence transient according to the JIP-test offers a practical and sensitive in vivo screening test for dark chilling tolerance in soybean.

Polymer, 2004

Series of samples of solid-phase chlorinated poly(ethylene) (CPE) have been studied by using both... more Series of samples of solid-phase chlorinated poly(ethylene) (CPE) have been studied by using both the methods of wide angle X-ray diffraction analysis (WAXD) and optical microscopy. Some basic crystallographic characteristics of CPE of 1.27 to 56.09 chlorine content were determined. The increase of chlorine content in the product was found to result in a relatively weak increase of the parameter a for meltcrystallized samples, whereas the parameter c values of the cold-sintered samples decreased. The crystallite sizes in the [110] and [020] directions for the melt-crystallized samples increased to the higher extent up to, approximately, 10% chlorine content, as compared to those of CPE available as powder or pellets. The degree of crystallinity was reduced as the chlorine content increased, but, even with 56% chlorine introduced, the polymer had a crystalline-amorphous structure. The optical micrographs showed that, up to 40% Cl, CPE had crystalline structure dominated by the formation of spherolites whereas, at higher chlorine content, structures of the lower order of crystallinity were formed. These observed changes were predominantly determined by the defects in the PE crystals, resulting from the inclusion of a certain fraction of chloromethylene groups therein.

Nanopesticides, 2020

Understanding the interactions between engineered nanomaterials and the environment is essential ... more Understanding the interactions between engineered nanomaterials and the environment is essential for unbiased assessments of their agricultural applications. Nano-based pesticides can potentially be safer and/or more efficient than their conventional analogs. However, there is limited information about how nanopesticides influence physiology and metabolism during their interactions with plants, particularly, related to its mode of action. The main question herein is about the interaction between nanopesticides and plants. In this chapter, we start from a theoretical discussion on the complex organization of biological systems, offering a variety of examples showing the effects of nanopesticides from uptake to the mode of action. Moreover, we discuss different examples, how physiological and metabolic responses can help us to understand the behavior of plants exposed to nano-based pesticides. Finally, we demonstrate that prediction models can be used as a routine tool for monitoring and classifying plant response according to their degree of resistance or tolerance to determined nanopesticide, aiming to understand the specific characteristics of nanopesticides into plant systems.

Environmental Chemistry Letters, 2003

In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing m... more In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry.

Open Journal of Ecology, 2021

Processing pineapple industry produces huge amounts of waste thus contributing to worsen the glob... more Processing pineapple industry produces huge amounts of waste thus contributing to worsen the global environmental problem. Valorising pineapple waste through further processing until it is transformed into valuable products using environmentally friendly techniques is both, a challenge, and an opportunity. The aim of this review is to characterize and highlight the phytochemical constituents of pineapple peel, their biological activity, and to evaluate the current state-of-art for the utilization of pineapple waste from the processing industry for obtaining pharmaceuticals, food, and beverages, biocombustibles, biodegradable fibers, and other different usage. Pineapple residues are rich in many bioactive compounds such as ferulic acid, vitamin A and C as antioxidant, and containing alkaloids, flavonoids, saponins, tannins, cardiac glycoside, steroids, triterpenoids and phytosterols may provide a good source of several beneficial properties, as well as bromelain that showed significant anticancer activity. Also, pineapple processing residues contain important volatile compounds used as aroma enhancing products and have high potential to produce value-added natural essences.

En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuron... more En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuronales artificiales para analizar señales de fluorescencia clorofílica (FC), con el fin de identificar y clasificar grupos de plantas de Vigna unguiculata (L.) Walp (fríjol) cultivadas en medios hidropónicos que contenían diferentes cantidades de nitrógeno (N) y las señales de fluorescencia de otro grupo de plantas cuyas semillas fueron inoculadas antes de su germinación con la bacteria Rhizobium variedad NGR232. Previo al entrenamiento neuronal se realizó un exhaustivo análisis estadístico multivariante, con la finalidad de detectar diferencias en los vectores de medias de los medios de cultivo y reducir el número de variables o puntos de las curvas de fluorescencia. El objetivo principal de este trabajo es desarrollar una herramienta para identificar la carencia de N en plantas de fríjol y otras leguminosas de mayor producción en agricultura. (N) and fluorescence signals from another group of plants whose seeds were inoculated prior to germination with the NGR232 variety Rhizobium bacteria. Before the ANN training, it was held an exhaustive multivariate statistical analysis for identifying differences among the means vectors of the growth media and reducing the numbers of variables or fluorescence curve points. The main objective of this work is to develop a tool for identifying N deficiency in pea's plants and other legumes with high production in agriculture.

In this work a statistical analysis-based methodological approach for a pattern recognition syste... more In this work a statistical analysis-based methodological approach for a pattern recognition system using discriminant analysis and neural networks is used for the classification of Pisum sativum (peas) according to the drought resistance. The statistical techniques used in the exploratory analysis are a fundamental tool in the creation of variables sets and observations for the model adjustment in the neural models and in the discriminant models.

The aim of this study is to develop a method to monitor coral activity by monitoring the photosyn... more The aim of this study is to develop a method to monitor coral activity by monitoring the photosynthetic activity of their zooxanthellae. The fast fluorescence rise measured with a PEA instrument is used to measure photosynthetic activity without injuring the subject and with some minimal disturbances (i.e. dark adaptation period). The rapidity of the measurement allows the accumulation of many data within short time. The reaction to different stresses
(heat, light…) can be rapidly quantified through the interpretation of the fluorescence curve (Tsimilli- Michael and Strasser 2000).
Before looking for the influence of different stresses applied to these organisms, we try first to describe and understand what underlies the cyclic variation observed in during long term monitoring. We compare the results obtained in one polyp of Actinodiscus sp. to another Actinodiscus sp. and a colony of Porites porites. This will give also a basis for comparing stress-induced reactions.The activity of a polyp of Actinodiscus sp. was measured each hour during several months. In this period the polyp grew and formed new polyps by budding.

In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing m... more In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry.

Cuadernos de la …, 2004

... La combinación de medida de fluores-cencia de la clorofila esta considerada una herra-mienta ... more ... La combinación de medida de fluores-cencia de la clorofila esta considerada una herra-mienta útil para distinguir los efectos estomáti-cos y no estomaticos en la limitación de la foto-síntesis (MAXWELL & JONHSON, 2000). ...

In this work a statistical analysis-based methodological approach for a pattern recognition syste... more In this work a statistical analysis-based methodological approach for a pattern recognition system using discriminant analysis and neural networks is used for the classification of Pisum sativum (peas) according to the drought resistance. The statistical techniques used in the exploratory analysis are a fundamental tool in the creation of variables sets and observations for the model adjustment in the neural models and in the discriminant models.

Journal of Plant Physiology

The purpose of this paper is to demonstrate the complementary utility of chlorophyll fast fluores... more The purpose of this paper is to demonstrate the complementary utility of chlorophyll fast fluorescence OJIP transient (from 50 microns to 1s) measurements in the aerial study of rows of trees. We identify limitations in photochemical events induced by urban injuries on Platanus acerfolia L. using the JIP-test procedure. The Performance Index (PIABS) showed the largest dynamic range to characterise the vitality of trees. Individual trees were graded into three quality groups based on the individual PIABS value compared to the overall average for trees in the alley. These groups are: high performers, with PIABS 50% higher than the alley average; normal trees, with a deviation from the alley average between -50% and %; and poor performers, whose deviation from the alley average was -50% or less. Trees also were grouped into five vitality categories on the basis of a stereoscopic and morphologic observation of the symmetry of tree crowns, percentage of defoliation and reflectance proper...

Ciencia e Ingeniería, 2015

En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuron... more En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuronales artificiales para analizar señales de fluorescencia clorofílica (FC), con el fin de identificar y clasificar grupos de plantas de Vigna unguiculata (L.) Walp (fríjol) cultivadas en medios hidropónicos que contenían diferentes cantidades de nitrógeno (N) y las señales de fluorescencia de otro grupo de plantas cuyas semillas fueron inoculadas antes de su germinación con la bacteria Rhizobium variedad NGR232. Previo al entrenamiento neuronal se realizó un exhaustivo análisis estadístico multivariante, con la finalidad de detectar diferencias en los vectores de medias de los medios de cultivo y reducir el número de variables o puntos de las curvas de fluorescencia. El objetivo principal de este trabajo es desarrollar una herramienta para identificar la carencia de N en plantas de fríjol y otras leguminosas de mayor producción en agricultura.

Biointerface Research in Applied Chemistry, 2021

Pineapple (Ananas comosus (L.) Merril), one of the major fruit crops, is mainly used for raw cons... more Pineapple (Ananas comosus (L.) Merril), one of the major fruit crops, is mainly used for raw consumption and for industrial juice production, which creates large amounts of residues. The United Nations Food and Agriculture Organization (FAO) has estimated that pineapple waste accounts for between 50 to 65 % of the total weight of the fruit. Industrial pineapple waste is a major source of pollution as important quantities of primary residues are not further processed. Pineapple waste contains bioactive compounds such as carotenoids, polyphenols, fibers, vitamins, enzymes, and essential oils. These phytochemicals can be used in the food industry, medicine and pharmacy, textile, and others. This review highlights essential oil and other bioactive compounds extracted from pineapple waste and the composition of pineapple essential oil. Pineapple peels are the potential raw material for essential oil extraction through various methods. Modern spectrometric methods have shown that essentia...

Journal of Agronomy and Crop Science, 2021

Science Access, 2001

Chlorophyll a fluorescence is a useful and non-invasive tool to screen for the effects of many bi... more Chlorophyll a fluorescence is a useful and non-invasive tool to screen for the effects of many biotic and abiotic parameters on photosynthesis in plants. The fluorescence of leaves after light excitation was measured with a portable fluorimeter (Plant Efficiency Analyser, built by Hansatech Instruments King?s Lynn Norfolk, PE 30 4 NE, GB) and the subsequent data were analysed using the JIP-test which produces parameters indicating PSII and photosynthesis activity. Seeds of Vigna unguiculata were sterilised before germinating and planting in Magenta jars (used in hydroponics culture) with a nutrient solution without nitrate (B&D solution). Half of the plants were inoculated with Rhizobium sp. NGR234 (1019 bacteria/ 100 µl) at roots level. Each half was then further divided and treated with KNO3 to produce four treatments. During 6 weeks measurements of several hundred measurements of 2 seconds are made on the leaves of inoculated and control plants, with or without different nitrate ...

Science Access, 2001

The fast fluorescence rise O-J-I-P (Strasser et al. 1995; Strasser and Strasser 1995) was used to... more The fast fluorescence rise O-J-I-P (Strasser et al. 1995; Strasser and Strasser 1995) was used to monitor coral health trough the photosynthetic activity of their zooxanthellae. The advantage is that such type of measurements are non invasive and the sample is exposed to the experimental light only during a few seconds. We have provided coral with "quasi-natural" conditions : a sea water aquarium of 60 l with the polyps living on rocks close to the glass wall of the container. The temperature and salinity were kept constant, illumination was provided with three 18W reef aquarium neon, and one 18W blue neon lamps. Chlorophyll fluorescence was induced for 10 to 20 seconds every hour with a PEA-Instrument (Plant Efficiency Analyser built by Hansatech Instruments King?s Lynn Norfolk, PE 30 4 NE, GB) during several months. Different species of Anthozoa are being studied. Two species of Actinodiscus, and one unidentified (probably Madracis) freshly collected from Bali (Indonesia...

South African Journal of Botany, 2014

Due to chilling sensitivity, minimum night temperatures represent the main constraint in soybean ... more Due to chilling sensitivity, minimum night temperatures represent the main constraint in soybean production in South Africa. In vivo quantification of photosystem II (PSII) function by direct chlorophyll fluorescence revealed that dark chilling (8°) inhibited PSII function in the extreme chill sensitive genotype, Java 29 (JAs) mainly by deactivating reaction centers and inhibiting the conversion of excitation energy to electron transport and electron transfer from reduced plastoquinone to the PSI end electron acceptors. Further analysis of the normalized fast fluorescence transients, revealed that in JAs, upon dark chilling, disengagement of the oxygen evolution complex (ΔV K band) occurred which coincided with a concomitant decrease in O 2 evolution measured in vitro. The chilling resistant Maple Arrow (MAr), though one night cold stress lead to a decrease in fluorescence emission at 2 ms (−ΔV J band) indicating a decrease in the Q A − concentration due to cold-induced slowdown of electron donation from P 680 , however showed clear signs of recovery after the second and third cold nights. The moderate chill sensitive genotype, Fiskeby V (FBm) responded in a fashion intermediate to above-mentioned extremes. A second experiment showed that in JAs the inhibitory effect increased with increasing time of exposure to light following dark chilling. Our data demonstrated that significant differences exist in the cold tolerance of different soybean genotypes: (a) In respect to activity criteria, expressed by the quantum yields for primary photochemistry φ Po = TR o /ABS, for electron transport from photosystem II to photosystem I as φ Eo = ET o /ABS and the efficiency, φ Ro = RE o /ABS, to reduce the end electron acceptors of photosystem I up to NADP; (b) In respect to stability criteria, dependent on structure and conformation, such as the capability of energetic cooperativity (grouping) among photosynthetic units quantified by the grouping probability for exciton movements within the energetically connected group of entire photosynthetic units. Therefore analyzing the O-J-I-P fluorescence transient according to the JIP-test offers a practical and sensitive in vivo screening test for dark chilling tolerance in soybean.

Polymer, 2004

Series of samples of solid-phase chlorinated poly(ethylene) (CPE) have been studied by using both... more Series of samples of solid-phase chlorinated poly(ethylene) (CPE) have been studied by using both the methods of wide angle X-ray diffraction analysis (WAXD) and optical microscopy. Some basic crystallographic characteristics of CPE of 1.27 to 56.09 chlorine content were determined. The increase of chlorine content in the product was found to result in a relatively weak increase of the parameter a for meltcrystallized samples, whereas the parameter c values of the cold-sintered samples decreased. The crystallite sizes in the [110] and [020] directions for the melt-crystallized samples increased to the higher extent up to, approximately, 10% chlorine content, as compared to those of CPE available as powder or pellets. The degree of crystallinity was reduced as the chlorine content increased, but, even with 56% chlorine introduced, the polymer had a crystalline-amorphous structure. The optical micrographs showed that, up to 40% Cl, CPE had crystalline structure dominated by the formation of spherolites whereas, at higher chlorine content, structures of the lower order of crystallinity were formed. These observed changes were predominantly determined by the defects in the PE crystals, resulting from the inclusion of a certain fraction of chloromethylene groups therein.

Nanopesticides, 2020

Understanding the interactions between engineered nanomaterials and the environment is essential ... more Understanding the interactions between engineered nanomaterials and the environment is essential for unbiased assessments of their agricultural applications. Nano-based pesticides can potentially be safer and/or more efficient than their conventional analogs. However, there is limited information about how nanopesticides influence physiology and metabolism during their interactions with plants, particularly, related to its mode of action. The main question herein is about the interaction between nanopesticides and plants. In this chapter, we start from a theoretical discussion on the complex organization of biological systems, offering a variety of examples showing the effects of nanopesticides from uptake to the mode of action. Moreover, we discuss different examples, how physiological and metabolic responses can help us to understand the behavior of plants exposed to nano-based pesticides. Finally, we demonstrate that prediction models can be used as a routine tool for monitoring and classifying plant response according to their degree of resistance or tolerance to determined nanopesticide, aiming to understand the specific characteristics of nanopesticides into plant systems.

Environmental Chemistry Letters, 2003

In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing m... more In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry.

Open Journal of Ecology, 2021

Processing pineapple industry produces huge amounts of waste thus contributing to worsen the glob... more Processing pineapple industry produces huge amounts of waste thus contributing to worsen the global environmental problem. Valorising pineapple waste through further processing until it is transformed into valuable products using environmentally friendly techniques is both, a challenge, and an opportunity. The aim of this review is to characterize and highlight the phytochemical constituents of pineapple peel, their biological activity, and to evaluate the current state-of-art for the utilization of pineapple waste from the processing industry for obtaining pharmaceuticals, food, and beverages, biocombustibles, biodegradable fibers, and other different usage. Pineapple residues are rich in many bioactive compounds such as ferulic acid, vitamin A and C as antioxidant, and containing alkaloids, flavonoids, saponins, tannins, cardiac glycoside, steroids, triterpenoids and phytosterols may provide a good source of several beneficial properties, as well as bromelain that showed significant anticancer activity. Also, pineapple processing residues contain important volatile compounds used as aroma enhancing products and have high potential to produce value-added natural essences.

En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuron... more En este trabajo se presenta una aplicación en reconocimiento de patrones, utilizando redes neuronales artificiales para analizar señales de fluorescencia clorofílica (FC), con el fin de identificar y clasificar grupos de plantas de Vigna unguiculata (L.) Walp (fríjol) cultivadas en medios hidropónicos que contenían diferentes cantidades de nitrógeno (N) y las señales de fluorescencia de otro grupo de plantas cuyas semillas fueron inoculadas antes de su germinación con la bacteria Rhizobium variedad NGR232. Previo al entrenamiento neuronal se realizó un exhaustivo análisis estadístico multivariante, con la finalidad de detectar diferencias en los vectores de medias de los medios de cultivo y reducir el número de variables o puntos de las curvas de fluorescencia. El objetivo principal de este trabajo es desarrollar una herramienta para identificar la carencia de N en plantas de fríjol y otras leguminosas de mayor producción en agricultura. (N) and fluorescence signals from another group of plants whose seeds were inoculated prior to germination with the NGR232 variety Rhizobium bacteria. Before the ANN training, it was held an exhaustive multivariate statistical analysis for identifying differences among the means vectors of the growth media and reducing the numbers of variables or fluorescence curve points. The main objective of this work is to develop a tool for identifying N deficiency in pea's plants and other legumes with high production in agriculture.

In this work a statistical analysis-based methodological approach for a pattern recognition syste... more In this work a statistical analysis-based methodological approach for a pattern recognition system using discriminant analysis and neural networks is used for the classification of Pisum sativum (peas) according to the drought resistance. The statistical techniques used in the exploratory analysis are a fundamental tool in the creation of variables sets and observations for the model adjustment in the neural models and in the discriminant models.

The aim of this study is to develop a method to monitor coral activity by monitoring the photosyn... more The aim of this study is to develop a method to monitor coral activity by monitoring the photosynthetic activity of their zooxanthellae. The fast fluorescence rise measured with a PEA instrument is used to measure photosynthetic activity without injuring the subject and with some minimal disturbances (i.e. dark adaptation period). The rapidity of the measurement allows the accumulation of many data within short time. The reaction to different stresses
(heat, light…) can be rapidly quantified through the interpretation of the fluorescence curve (Tsimilli- Michael and Strasser 2000).
Before looking for the influence of different stresses applied to these organisms, we try first to describe and understand what underlies the cyclic variation observed in during long term monitoring. We compare the results obtained in one polyp of Actinodiscus sp. to another Actinodiscus sp. and a colony of Porites porites. This will give also a basis for comparing stress-induced reactions.The activity of a polyp of Actinodiscus sp. was measured each hour during several months. In this period the polyp grew and formed new polyps by budding.

In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing m... more In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry.

Cuadernos de la …, 2004

... La combinación de medida de fluores-cencia de la clorofila esta considerada una herra-mienta ... more ... La combinación de medida de fluores-cencia de la clorofila esta considerada una herra-mienta útil para distinguir los efectos estomáti-cos y no estomaticos en la limitación de la foto-síntesis (MAXWELL & JONHSON, 2000). ...

In this work a statistical analysis-based methodological approach for a pattern recognition syste... more In this work a statistical analysis-based methodological approach for a pattern recognition system using discriminant analysis and neural networks is used for the classification of Pisum sativum (peas) according to the drought resistance. The statistical techniques used in the exploratory analysis are a fundamental tool in the creation of variables sets and observations for the model adjustment in the neural models and in the discriminant models.

Journal of Plant Physiology

The purpose of this paper is to demonstrate the complementary utility of chlorophyll fast fluores... more The purpose of this paper is to demonstrate the complementary utility of chlorophyll fast fluorescence OJIP transient (from 50 microns to 1s) measurements in the aerial study of rows of trees. We identify limitations in photochemical events induced by urban injuries on Platanus acerfolia L. using the JIP-test procedure. The Performance Index (PIABS) showed the largest dynamic range to characterise the vitality of trees. Individual trees were graded into three quality groups based on the individual PIABS value compared to the overall average for trees in the alley. These groups are: high performers, with PIABS 50% higher than the alley average; normal trees, with a deviation from the alley average between -50% and %; and poor performers, whose deviation from the alley average was -50% or less. Trees also were grouped into five vitality categories on the basis of a stereoscopic and morphologic observation of the symmetry of tree crowns, percentage of defoliation and reflectance proper...