We evaluated several mechanisms that enable saplings of Yucca filifera (Chabaud) to endure water shortage. Saplings were exposed to water shortage and subsequent rewatering inside a greenhouse. The response variables were maximum quantum efficiency (F-v/F-m), effective quantum yield of photosystem II (Phi(PSII)), nonphotochemical quenching (NPQ), electron transport rate (ETR), leaf relative water content, titratable acid (Delta H+), pigment content (chlorophylls a and b, total carotenoids, chlorophyll a+b/carotenoids ratio, and chlorophyll a/b ratio), antioxidant activity, and proline accumulation. We hypothesized that Y. filifera saplings tolerate water shortage, and that rewatering favors the sapling development. We found that F-v/F-m and Phi(PSII) values as well as Delta H+ and chlorophyll a/b ratio were strongly affected by water shortage, and their values reverted after rewatering. We also found higher NPQ, antioxidant activity, and proline content during the water-shortage treatment, which might represent mechanisms for preventing photodamage. The high ability of Y. filifera saplings to withstand stress caused by water shortage indicates that it could be a key species for conservation and restoration of degraded arid ecosystems.
