Plant "electrome" can be pushed toward a self-organized critical state by external cues: Evidences from a study with soybean seedlings subject to different environmental conditions.

In the present study, we have investigated how the low-voltage electrical signals of soybean seedlings change their temporal dynamic under different environmental conditions (cold, low light, and low osmotic potential). We have used electrophytografic technique (EPG) with sub-dermal electrodes inserted in 15-days-old seedlings located between root and shoot, accounting for a significant part of the individual seedlings. Herein, to work on a specific framework to settle this type of the study, we are adopting the term "electrome" as a reference to the totality of electrical activity measured. Taking into account the non-linear dynamic of the plants electrophysiology, we have hypothesized that the stimuli, as applied in a constant way, could push the system to a critical state, exhibiting spikes without a characteristic size, indicating self-organized criticality (SOC). The results from the power spectral density analysis (PSD), showed that the interval of the large majority of the ß exponents were between 1.5 and 3, indicating that the time series, regardless environmental conditions, showed long-range temporal correlation (long memory for ß≠0 and ß≠2). The analyses from the histograms of the runs showed different patterns of distributions concerning the experimental conditions. However, the runs exhibiting typical spikes, mostly under low light and osmotic stress, showed power law distribution with exponent µ ≅ 2, which is an indicative for SOC. Overall, our results have confirmed that the temporal dynamic of the electrical signaling shows a complex non-linear behavior with long-range persistence. Moreover, the hypothesis that plant electrome can exhibit a self-organized critical state evoked by environmental cues, dissipating energy by bursts of electrical spikes without a characteristic size, was reinforced. Finally, new perspectives for research and additional hypothesis were presented.

Aclimatação e fisiologia de mudas de guanandi cultivadas em telas de sombreamento foto-protetoras / Acclimation and physiology of guanandi seedlings grown under photoprotective shade screens

A luminosidade é o fator mais importante no crescimento e desenvolvimento de plântulas. As plantas modificam seu modelo de crescimento e alocação de recursos em resposta ao ambiente luminoso. Foram avaliados parâmetros biométricos, bioquímicos e fisiológicos de mudas de Guanandi cultivadas a pleno sol e sob 50 % de sombreamento, utilizando telas foto-conversoras (azul, preto e vermelho), sendo analisadas no verão e outono de 2012. As mudas cultivadas a pleno sol apresentaram maior qualidade, vigor e acumulo de massa. As telas alteraram o microclima, causando alterações nas trocas gasosas e limitando o desenvolvimento das mudas. A atividade das enzimas antioxidantes mostrou que os tratamentos não causaram estresse oxidativo. O Guanandi apresentou ampla capacidade de aclimatação ao sombreamento e ao sol pleno. Contudo obteve melhores resultados a pleno sol, mesmo sendo considerada espécie tardia a clímax.

The luminosity is the most important factor in the growth and development of seedlings. Plants can change their growth model and resource allocation in response to the light environment. Biometric, biochemical and physiological parameters of Guanandi seedlings grown in full sun and under 50% shade using photo-converter (blue, black and red) screens were evaluated and analyzed in the summer and fall of 2012 The seedlings grown in full sunlight showed higher quality, vigour and mass accumulation. The screens have changed the microclimate, causing changes in gas exchange and limiting the growth of seedlings. The activity of antioxidant enzymes showed that the treatments did not cause oxidative stress. Guanandi presented ample capacity for acclimation to shade and full sun. However performed better in full sun, even been considered late climax species.

Aclimatação e fisiologia de mudas de guanandi cultivadas em telas de sombreamento foto-protetoras / Acclimation and physiology of guanandi seedlings grown under photoprotective shade screens

A luminosidade é o fator mais importante no crescimento e desenvolvimento de plântulas. As plantas modificam seu modelo de crescimento e alocação de recursos em resposta ao ambiente luminoso. Foram avaliados parâmetros biométricos, bioquímicos e fisiológicos de mudas de Guanandi cultivadas a pleno sol e sob 50 % de sombreamento, utilizando telas foto-conversoras (azul, preto e vermelho), sendo analisadas no verão e outono de 2012. As mudas cultivadas a pleno sol apresentaram maior qualidade, vigor e acumulo de massa. As telas alteraram o microclima, causando alterações nas trocas gasosas e limitando o desenvolvimento das mudas. A atividade das enzimas antioxidantes mostrou que os tratamentos não causaram estresse oxidativo. O Guanandi apresentou ampla capacidade de aclimatação ao sombreamento e ao sol pleno. Contudo obteve melhores resultados a pleno sol, mesmo sendo considerada espécie tardia a clímax.(AU)

The luminosity is the most important factor in the growth and development of seedlings. Plants can change their growth model and resource allocation in response to the light environment. Biometric, biochemical and physiological parameters of Guanandi seedlings grown in full sun and under 50% shade using photo-converter (blue, black and red) screens were evaluated and analyzed in the summer and fall of 2012 The seedlings grown in full sunlight showed higher quality, vigour and mass accumulation. The screens have changed the microclimate, causing changes in gas exchange and limiting the growth of seedlings. The activity of antioxidant enzymes showed that the treatments did not cause oxidative stress. Guanandi presented ample capacity for acclimation to shade and full sun. However performed better in full sun, even been considered late climax species.(AU)