Marcos Antonio Bacarin

Freshwater swamp forests (FSFs) are flood-prone ecosystems on nutrient-rich alluvial soils that provide important ecosystem services, yet remain underrepresented in wetland research and management. This integrative review synthesizes current knowledge on FSFs with emphasis on three interconnected themes: (i) ecological definition, classification, and hydrological dynamics; (ii) the role of microtopography and evapotranspiration in regulating water storage and fluxes; and (iii) potential responses of these coupled processes to climate change. Although the “sponge” metaphor is seldom explicitly applied to FSFs, the reviewed literature consistently shows that water retention, delayed release, and vegetation-mediated fluxes are functionally linked, albeit often studied separately. Fine-scale surface heterogeneity, particularly hummocks and depressions, emerges as a key mechanism promoting water redistribution, groundwater recharge, and the persistence of localized refugia and microhabitats. At the same time, climate change-driven shifts in precipitation, drought frequency, heat stress, and disturbance regimes may weaken these regulatory functions and reduce ecosystem resilience. We therefore propose the “sponge–pump framework” as a conceptual model linking hydrological storage (“sponge”) and vegetation-driven water fluxes (“pump”) to explain how FSFs regulate water movement, support biodiversity, and contribute to ecosystem services across spatial and temporal scales. The framework also highlights the need for standardized quantification, broader geographic coverage, and greater integration of microtopographic processes in wetland conservation, restoration, and climate adaptation strategies.

Resposta diferencial ao déficit hídrico em dois cultivares de feijão comum - DOI:10.5039/agraria.v12i3a5457

WATER DEFICIT AFFECTS GAS EXCHANGE IN PEACH TREES CULTIVAR CHIMARRITA GRAFTED ONTO DIFFERENT ROOTSTOCKS     LETICIA NEUTZLING RICKES, ELSA KUHN KLUMB, CARLOS DAVI SANTOS E SILVA, MARCOS ANTONIO BACARIN, VALMOR JOÃO BIANCHI ¹ Dr.(a) em Fisiologia Vegetal pela Universidade Federal de Pelotas, Instituto de Biologia, Departamento de Botânica, Campus Universitário, Capão do Leão, RS – Brasil, E-mail: leticiarickes@hotmail.com, carlosdavi_santos@yahoo.com.br ² Mestra em Fisiologia Vegetal pela Universidade Federal de Pelotas, Instituto de Biologia, Departamento de Botânica, Campus Universitário, Capão do Leão, RS – Brasil, E-mail: elsakk91@yahoo.com.br ³ Prof. Dr. Universidade Federal de Pelotas, Instituto de Biologia, Departamento de Botânica, Campus Universitário, Capão do Leão, RS – Brasil, E-mail: bacarin@ufpel.edu.br, valmorjb@yahoo.com     1 ABSTRACT The aim was to investigate the effect of the water deficit on the gas exchange of Chimarrita plants grafted onto five different rootstocks (Tsukuba 1, Tsukuba 2, Tsukuba 3, Aldrighi 1, and Selection UFPel 0402), i.e., five combinations ‘Chimarrita’/rootstocks. The factorial scheme consisted of two water conditions (control and water deficit) and eight days of evaluation (0, 1^st, 2^nd, 3^rd, 4^th, 6^th, 7^th, and 9^th, the latter two were the recovery period). Gas exchange was assessed with the aid of the portable CO₂ infrared analyzer. Results were subjected to the analysis of variance (p≤0.05) by using Tukey’s test in order to compare the means between treatments at each day of stress for each ‘Chimarrita’/rootstocks combination. It was found that the different ‘Chimarrita’/rootstocks combinations showed a distinct physiological behavior regarding the initial water-deficit tolerance. Plants consisting of the combination ‘Chimarrita/Aldrighi 1’ had the highest initial water-deficit tolerance. The reduction in the net assimilation rate in face of the water deficit is not only related to the stomatal limitation, suggesting that there may also be non-stomatal limitations. Seventy-two hours after providing irrigation back to plants, all combinations evaluated showed an overall resilience of the physiological performance.   Keywords: Prunus persica, abiotic stress, stomatal conductance, net assimilation rate. RICKES, L. N.; KLUMB, E. K.; SILVA, C. D. S. e; BACARIN, M. A.; BIANCHI, V. J. DÉFICIT HÍDRICO AFETA AS TROCAS GASOSAS EM PESSEGUEIRO CULTIVAR CHIMARRITA ENXERTADA SOBRE DIFERENTES PORTAENXERTOS 2 RESUMO O objetivo foi avaliar o efeito do déficit hídrico sobre as trocas gasosas em plantas da cultivar Chimarrita enxertada sobre cinco diferentes portaenxertos (Tsukuba 1, Tsukuba 2, Tsukuba 3, Aldrighi 1 e Seleção UFPel 0402), ou seja, cinco combinações ‘Chimarrita’/portaenxertos. O esquema fatorial foi composto de duas condições hídricas (controle e déficit hídrico) e oito dias de avaliação (0, 1º, 2º, 3º, 4º, 6º, 7º e 9º, os dois últimos sendo período de recuperação). As trocas gasosas foram avaliadas com um analisador portátil a infravermelho de CO_2. Os resultados foram submetidos a análise de variância (p≤0,05), utilizando-se o teste de Tukey para comparação de médias entre os tratamentos em cada dia de estresse de cada combinação ‘Chimarrita’/portaenxertos. Verificou-se que as diferentes combinações de ‘Chimarrita’/portaenxertos apresentaram comportamento fisiológico diferencial para a tolerância inicial ao déficit hídrico. Plantas compostas pelas combinações de enxertia entre ‘Chimarrita’/Adrighi 1’ foram as que apresentaram a maior tolerância inicial ao déficit hídrico. A redução da taxa assimilatória líquida perante o déficit hídrico, não está relacionada principalmente à limitação estomática, sugerindo-se que ocorrem também limitações não estomáticas. Após 72h do retorno da irrigação das plantas, todas as combinações avaliadas demonstraram total capacidade de recuperação do desempenho fisiológico.   Palavras-chave: Prunus persica, estresse abiótico, condutância estomática, taxa assimilatória líquida.

Soil flooding is a stress condition that causes changes in hydric relationships and in the metabolism of crops, thereby affecting their productivity. To evaluate the effects of soil flooding on the chlorophyll a fluorescence transient, as well as gas exchange and Ricinus communis growth, young plants of the ‘AL Guarany 2002’ and ‘IAC Guarani’ cultivars, grown in a greenhouse, were subjected to flood conditions by maintaining a layer of water 2-3 cm above the soil. The stressed plants showed drastic reduction in net CO2 assimilation and growth variables. There was, however, an increase in performance index (PIABS e PITOTAL) at different moments of stress between the two cultivars. In general, R. communis plants possess mechanisms to protect the electron transport chain during a period of stress, without causing damage and reducing functionality. However, this is not enough to maintain photosynthetic activity owing to the decrease in stomatal conductance and intrinsic carboxylation efficiency, which affects biomass accumulation in stressed plants. In summary, this study found that the ‘AL Guarany 2002’ was found to be more sensitive to stress than the ‘IAC Guarani’ was.

Analysis of transient and modulated fluorescence of chlorophyll a were made at one-hour intervals during an eight-hour period starting at 07:30h aiming to study mechanisms of photoprotection against high radiation and temperature in Gallesia integrifolia plants. Seeds were germinated inside plastic pots containing soil as substrate. At 120 days after emergence, chlorophyll fluorescence measurements were performed using Handy-PEA and FMS2 fluorometers. During the course of a day, an increase and a subsequent decrease in temperature and in photosynthetic active radiation were observed until 12:30h. Changes in transient kinetic curves of chlorophyll a fluorescence were identified. This resulted in changes in JIP test parameters. An increase during the period of high radiation and temperature may be stressed in relation to variables related to dissipation flux and appearance of positive -K and -L bands. Considering the modulated fluorescence, high values of non-photochemical quenching coefficients associated with lower values of effective photochemical efficiency of the photosystem II (FV'/ FM') and current photochemical efficiency of PSII (φPSII) could be observed during early morning. This was probably the result of an inhibition of the biochemical phase of photosynthesis. It can be concluded that Gallesia integrifolia decrease its photochemical activity with the increase in the photosynthetic active radiation, demonstrating a photoinhibitory effect under high irradiance conditions, but without irreversible damages to the photosynthetic apparatus.