Ádrya Vanessa Lira Costa

Electrophysiological signals in plants, which are a part of the plant electrome, are essential for mediating responses to environmental stimuli but exhibit complex, non-linear dynamics that challenge conventional analyses. Here, we introduce the time dispersion analysis of features (TDAF), a novel method that preserves temporal integrity by assessing the dispersion of signal features over time by segmenting time series and evaluating the temporal evolution of extracted features. Unlike traditional methods, such as moving averages or stationarity-based models, that summarize the signal or lose temporal information, TDAF analyzes the evolution of features over time, maintaining their dynamic structure. We applied TDAF to investigate the effects of a moderate static magnetic field (~ 0.4 mT) on the electrome of common bean plants (Phaseolus vulgaris L.). Signals from 30 plants were recorded before and during magnetic field exposure, generating time series with 225,000 points each. Features such as approximate entropy (ApEn), detrended fluctuation analysis (DFA), fast Fourier transform (FFT), power spectral density (PSD), and average band power (ABP) were analyzed. Our results suggest that magnetic field exposure tends to reduce signal amplitude but preserves the structural complexity and temporal patterns of the electrome, indicating modulation without loss of information processing capacity. TDAF proved effective for detecting subtle physiological changes and offers a valuable tool for advancing plant electrophysiology, bioelectromagnetic research, and studies involving complex and long-duration biological signals.

Fruits, like other parts of the plant, appear to have a rich electrical activity that may contain information. Here, we present data showing differences in the electrome complexity of tomato fruits through ripening and discuss possible physiological processes involved. The complexity of the signals, measured through approximate entropy, varied along the fruit ripening process. When analyzing the fruits individually, a decrease in entropy values was observed when they entered the breaker stage, followed by a tendency to increase again when they entered the light red stage. Consequently, the data obtained showed a decrease in signal complexity in the breaker stage, probably due to some physiological process that ends up predominating to the detriment of others. This result may be linked to processes involved in ripening, such as climacteric. Electrophysiological studies in the reproductive stage of the plant are still scarce, and research in this direction is of paramount importance to understand whether the electrical signals observed can transmit information from reproductive structures to other modules of plants. This work opens the possibility of studying the relationship between the electrical activity and fruit ripening through the analysis of approximate entropy. More studies are necessary to understand whether there is a correlation or a cause-response relationship in the phenomena involved. There is a myriad of possibilities for the applicability of this knowledge to different areas, from understanding the cognitive processes of plants to achieving more accurate and sustainable agriculture.

To survive in a dynamic environment growing fixed to the ground, plants have developed mechanisms for monitoring and perceiving the environment. When a stimulus is perceived, a series of signals are induced and can propagate away from the stimulated site. Three distinct types of systemic signaling exist, i.e., (i) electrical, (ii) hydraulic, and (iii) chemical, which differ not only in their nature but also in their propagation speed. Naturally, plants suffer influences from two or more stimuli (biotic and/or abiotic). Stimuli combination can promote the activation of new signaling mechanisms that are explicitly activated, as well as the emergence of a new response. This study evaluated the behavior of electrical (electrome) and hydraulic signals after applying simple and combined stimuli in common bean plants. We used simple and mixed stimuli applications to identify biochemical responses and extract information from the electrical and hydraulic patterns. Time series analysis, comparing the conditions before and after the stimuli and the oxidative responses at local and systemic levels, detected changes in electrome and hydraulic signal profiles. Changes in electrome are different between types of stimulation, including their combination, and systemic changes in hydraulic and oxidative dynamics accompany these electrical signals.

The physiological processes underlying fruit ripening can lead to different electrical signatures at each ripening stage, making it possible to classify tomato fruit through the analysis of electrical signals. Here, the electrical activity of tomato fruit (Solanum lycopersicum var. cerasiforme) during ripening was investigated as tissue voltage variations, and Machine Learning (ML) techniques were used for the classification of different ripening stages. Tomato fruit was harvested at the mature green stage and placed in a Faraday's cage under laboratory-controlled conditions. Two electrodes per fruit were inserted 1 cm apart from each other. The measures were carried out continuously until the entire fruits reached the light red stage. The time series were analyzed by the following techniques: Fast Fourier Transform (FFT), Wavelet Transform, Power Spectral Density (PSD), and Approximate Entropy. Descriptive analysis from FFT, PSD, and Wavelet Transform were used for PCA (Principal Component Analysis). Finally, ApEn, PCA1, PCA2, and PCA3 were obtained. These features were used in ML analyses for looking for classifiable patterns of the three different ripening stages: mature green, breaker, and light red. The results showed that it is possible to classify the ripening stages using the fruit's electrical activity. It was also observed, using precision, sensitivity, and F1-score techniques, that the breaker stage was the most classifiable among all stages. It was found a more accurate distinction between mature green × breaker than between breaker × light red. The ML techniques used seem to be a novel tool for classifying ripening stages. The features obtained from electrophysiological time series have the potential to be used for supervised training, being able to help in more accurate classification of fruit ripening stages.

A aveia branca (Avena sativa L.), vem sendo bastante utilizada como sistema de rotação entre culturas pois tem grande capacidade de recuperação de solos, principalmente nos períodos de outono/inverno, se tornando assim uma alternativa economicamente viável para as regiões brasileiras de clima frio. Porém, devido as mudanças climáticas e a escassez de chuvas, fatores como a salinização do solo são capazes de impactar negativamente a produção desta cultura. Com isso, o objetivo deste trabalho, foi avaliar o efeito de diferentes concentrações de NaCl nos parâmetros fisiológicos e fotossintéticos em plantas de aveia branca. O experimento foi realizado em casa de vegetação, as plantas foram submetidas a diferentes concentrações de NaCl (0, 50, 100 e 150 mM) e 14, 21 e 28 dias após a semeadura, foram feitas as análises de trocas gasosas e medições com clorofilômetro, avaliando os índices de clorofila, flavonoides, antocianinas e balanço do nitrogênio. Os resultados obtidos no presente estudo demonstram que as plantas de aveia branca submetidas à concentrações maiores que 100 NaCl (nM) podem ter queda na produtividade devido à redução dos parâmetros analisados.Palavras-chave: Avena sativa; fisiologia; salinidade.