Seedlings of dry forest-adapted species resume growth after desiccation

Abstract

Desiccation tolerance (DT) in germinated seeds is directly related to the success of seedling survival of seasonally dry tropical forest and woodland (SDTFW) species. The objective of this study was to evaluate whether the seeds of Anadenanthera colubrina and Cenostigma pyramidale present post-germinative DT and until what stage of seedling development does tolerance persist. Seedlings of different sizes were separated into four categories of initial root length (IRL) and dried for 24 and 72 h. Seedling survival was evaluated 7 and 14 days after rehydration. DT was considered when the seedlings resumed growth after desiccation and rehydration to the original water content. Both species were tolerant to post-germination desiccation. Cenostigma pyramidale seedlings with IRL as low as 5-mm survived desiccation followed by up to 14 days of rehydration, while most larger seedlings (with IRL from 5.00 to 10.99 mm) failed to resume growth after desiccation/ rehydration. Smaller seedlings before desiccation showed greater growth and longer seedling lengths after rehydration for both species. Anadenanthera colubrina seedlings with IRL between 3.00 and 10.99 mm had their growth compromised when desiccated for a longer period. As a survival strategy, the seedlings of both species lose the primary root and produce adventitious roots after desiccation. Therefore, the survival of seedlings of both species to desiccation has a direct effect on the recruitment of SDTFW species.