Caracterização das Respostas Morfofisiológicas de Espécies nativas do Gênero Piper Sob Déficit Hídrico Recorrente

Abstract

In Brazil, four genus are found with about 400 species, belonging to the Piperaceae family. The secondary metabolism of this family contains metabolites from mixed biosynthesis, resulting in the production of amides or aromatic compounds. The species P. aduncum L is a cultivable species that can be industrialized both in small and large scale, Piper arboreum Aubl. var. arboreum and P. tuberculatum Jacq. (Piperaceae), are known as long pepper and are marketed as traditional herbal products. Of all the resources plants need to grow and function, water is the most abundant and often the most limiting. Plant tolerance to drought is a set of mechanisms, which can work in isolation or not, to avoid or tolerate periods of water deficit. The objective of this work was to evaluate changes in the photosynthetic apparatus in three species of Piper subjected to water suspension cycles through the analysis of gas exchange, SPAD, transient fluorescence analysis of chlorophyll \\\"a\\\", quantification of photosynthetic pigments (Chlorophyll a, b and total and β−Carotene, Lycopene, Zeaxanthin, α−Carotene, β−Cryptoxanthin and Total Carotenoids), evaluate the growth and allocation of biomass. Parameter data were submitted to analysis of variance and means were grouped by the Scott Knott test (p<0.05). The drought regimes were enough to generate significant reductions in the rates of net carbon assimilation (A), more evident in P. aduncum, for the variable transpiration (E), along the two cycles of water suspension, P. tuberculatum was the only one that showed statistical difference when looking at the data of the species within the treatment and all differed significantly from their respective controls. As for the water use efficiency (WUE), the species P. aduncum was the closest to the values of the control plants. In the green color intensity, estimated by the SPAD, a trend line was applied to the water deficit values, and the species P. tuberculatum showed a tendency to decrease in values throughout the experiment. The assessment of transient chlorophyll “a” fluorescence was performed in the last cycle of water suspension and rehydration. The water deficit caused a reduction in the number of open reduction centers, thus causing an increase in Fo, this increase being more evident in P. arboreum. The species P. tuberculatum had the oxygen evolution complex and the energetic connectivity of photosystem II components affected in the analysis of the day of its rehydration. P. aduncum had the highest mean root length and P. tuberculatum had the greatest difference in the number of leaves, being smaller in relation to its controls. Regarding height, stem diameter, number of roots and root volume, there were no differences in relation to control plants.