Hidratação descontínua: aprimoramento da expressão do potencial fisiológico de sementes de Ormosia grossa Rudd e Schizolobium parahyba var. amazonicum (Huber x Ducke) Barneby em condição de estresse hídrico

Abstract

Most Terrestrial Systems Models foresee an increase in the intensity of the dry season in the Amazon in the 21st century. Thus, it is essential to investigate the seed germination behavior of native species under stress conditions and strategies to guarantee their establishment. Given the above, this paper aims to describe the hydration curve pattern seeds of the forest species native to the Amazon Ormosia grossa Rudd and Schizolobium parahyba var. amazonicum and evaluate the effect of discontinuous hydration on seed germination under water stress conditions. For this, the seeds were submitted to 0 (control), 1, and 2 cycles of discontinuous hydration, and sown under simulated water stress conditions (0, -0.2; -0.4; -0.6 and -0.8 MPa). Seeds of O. grossa had a three-phase pattern in the hydration curve and seeds of S. parahyba var. amazonicum had a two-phase pattern. Both hydration curves fit the Fourier Maia curve with a series of two terms. The germination of the two studied species is positively influenced by discontinuous hydration cycles under stress conditions. Seeds of O. grossa and S. parahyba var. amazonicum, when submitted to 2 cycles of discontinuous hydration, generally present better germination performance and can remain quiescent when subjected to water stress conditions.