Sementes de espécie do Chaco possuem memória hídrica como adaptação ao estresse

Abstract

Parkinsonia praox (Ruiz & Pav.) Hawkins (Fabaceae) occurs in the Chaco located south of the Pantanal in Brazil. This environment has semi-arid characteristics in the dry part, requiring adaptations for reproductive success, such as water memory. This work aims to determine if the seeds of P. praecox have water memory and understand the effects of the Hydration and Dehydration Cycles (CHD) during an imbibition on the germination and the formation of normal seedlings in conditions of water deficit. Initially, the temperature for germination and osmotic potential in polyethylene glycol6000 (PEG 6000) were established for the tests. The seeds used by CHD (0, 1, 2 and 3 cycles) correspond to 33%, 56% and 58% hydration, from the soak curve and placed to germinate under water restriction conditions - 0.8 MPa. The ideal temperature for germination was 30 ºC. Germination in PEG-6000 occurs up to -1.0 MPa and in seedling formation -0.8 Mpa. CHD increased tolerance to water deficit, increased speed, and percentage of germination. It was concluded that P. praecox seeds submitted to two CHD with 56% hydration, have better responses to conditions of water deficit.