Caracterização morfofisiológica de pirênios de Spondias tuberosa Arruda

Abstract

The production chain of native fruits has grown in Brazil and required the implementation of techniques that enable the characterization of plants as well as the development and adaptation of methodologies for the analysis of seeds with dormancy. Spondias tuberosa Arruda, the umbuzeiro, is an anacardiaceae native to the Caatinga, with extractive production and great socio-environmental importance. The species has morphophysiological adaptations that serve as a model for elucidating strategic mechanisms for drought survival. The lignified pyrene presents dormancy and has been one of the main obstacles to the production of seedlings by sexual propagation. This research sought to characterize the pyrene morphophysiology of Spondias tuberosa Arruda. For this purpose, freshly dispersed and stored pyrenes, treated or not with abrasive agents and gibberellin (GA3) were subjected to analysis. The morphophysiological responses to thermal and water stress were obtained after direct immersion of the pyrenes in water, under different temperatures (10, 20, 30 and 40°C) and in polyethylene glycol 6000 (PEG 6000) solutions of different concentrations (potentials of -2 at -8 Mpa, at a temperature of 30°C). The viability and vigor of hydrated and dehydrated pyrenes were determined from the construction of imbibition curves under different conditions of temperature and imbibition times and from the analysis of the germinability variables, abscisic acid concentration (ABA) and level of respiratory tissue activity, submitted to the tetrazolium test. The tetrazolium test was suitable for use in umbuzeiro pyrenes, with the adoption of spectrophotometry in the visible region for the interpretation of results. The experiments were conducted in a completely randomized design, with five replications per treatment, in a factorial scheme, with descriptive statistics, regressions and analysis of canonical variables estimated with the aid of the software R studio. Pyrenes soaked in solutions with water potentials (ψw) of -2 to -6 MPa showed an increase in ABA content and inhibition of germination. The newly dispersed seed had a high ABA content, not germinating under ideal conditions of water content, oxygenation and temperature. Germination in the species occurs after 9 months of storage of the pyrenes and a significant reduction in the ABA content. The germination temperature for the species is 20 and 30°C. The umbuzeiro pyrenes showed primary and secondary dormancy. The tetrazolium test for determining the viability of umbuzeiro pyrenes could be conducted using embryonic tissue samples, excised from pyrenees soaked in water for 24 hours, at room temperature, stained in tetrazolium salt solution, for 16 hours in the absence of light, in the concentration of 0,5%. The triphenylformazan quantification method by spectrophotometry for the interpretation of the tetrazolium test is applicable as a quality analysis methodology for umbuzeiro pyrenes.