High recovery from either waterlogging or drought overrides any beneficial acclimation of Chloris gayana facing a subsequent round of stress

MOLLARD FPO; DI BELLA CE; LOGUZZO MB; GRIMOLDI AA; STRIKER GG

Plants

MDPI

Año: 2022

2223-7747

Climate models predict that plants will face extreme fluctuations in water availabilityin future global change scenarios. Then, forage production will be more frequently subjected tothe destabilizing pressure of sequentially occurring waterlogging and drought events. While theisolated effects of drought (D) and waterlogging (WL) are well characterized, little is known aboutthe consequences when both stresses occur sequentially. We hypothesized that plants sequentiallysubjected to opposite water scenarios (D followed by WL or vice versa) are less stress tolerant thanplants experiencing repetitions of the same type of water stress (i.e., D + D or WL + WL) due tocontrasting acclimation and allocation to either shoots (WL) or roots (D). Chloris gayana (a tropicalforage grass capable of tolerating either D and WL) plants were randomly assigned to nine treatments (a sequence of two stress rounds—WL or D—each followed by a recovery phase at field capacity). Relative growth rates and allometric responses were measured after each stress round and recovery period. In the first round of stress, both WL and D reduced plant RGR similarly, despite their allocation being opposite—prioritizing shoots or roots under WL and D, respectively. The highrecovery displayed after either WL or D overrode any possible acclimation of the plants facing asecond round of water stress. We conclude that the tolerance of C. gayana to sequential water stress (either for WL or D) is likely to depend more heavily on its recovery ability than on its previous adjustment to any stress scenario that may evoke memory responses. Knowledge like this could help improve forage grass breeding and the selection of cultivars for poorly drained soils subject to sequential stress events.