How does temperature influence hydration memory in seeds and seedlings of Crotalaria retusa L. (Fabaceae)?

Abstract

In 24 years of studies on seed-hydration memory, the benefits promoted by cycles of hydration and dehydration in germination and the initial development of plants, such as increased tolerance to environmental stress, have been unraveled. However, little is still known about how the combination of different factors influences this memory. This study aimed to investigate the effects of hydration and dehydration (HD) cycles at different temperatures on the germination and initial development of Crotalaria retusa seedlings under water deficit conditions. HD cycles were simulated as pre-germination treatments, and the seeds were subjected to 0, 1, 2, or 3 cycles at 25, 30, or 40 °C. After germination, the seedlings were subjected to 10 days of water suppression (water deficit) and 10 days of recovery. The results showed that HD cycles and temperature had a positive effect on germination, although higher temperatures and more cycles decreased germinability. Seedling growth was reduced in the combination of HD cycles, temperature, and water deficit, which can be a strategy of tolerance to water stress by plants. The passage through HD cycles promoted changes in germination and development of C. retusa, which can aid in the process of invasion of the species in arid and semi-arid environments and can bring competitive benefits in relation to native species. Overall, the study highlights the importance of HD cycles for the successful establishment of C. retusa in harsh environments.