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

Climate models predict that plants will face extreme fluctuations in water availability in future climate change scenarios. Then, forage production will be more frequently subjected to the destabilizing pressure of sequentially happening waterlogging and drought events. While the isolated effect of drought (D) and waterlogging (WL) are well characterized, little is known about the consequences when both stresses occur sequentially. We hypothesized that plants sequentially subjected to opposite water scenarios (D followed by WL or vice versa) are less stress tolerant than plants experiencing sequences of the same water stress (i.e., D+D or WL+WL) due to contrasting acclimation and allocation to shoot (WL) or roots (D). Plants of Chloris gayana (a tropical forage grass able to tolerate either D and WL) were randomly assigned to nine treatments (a sequence of two stress rounds -WL or D-, fol-lowed each one by a recovery phase at field capacity). Relative growth rate and allometric responses were measured after each stress round and recovery period. In the first round of stress, either WL or D similarly reduced plant RGR despite allocation being opposite – prioritized shoots or roots under WL and D, respectively. The high recovery displayed af-ter either WL or D overrode any possible acclimation to face a second round of water stress. We conclude that 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 could evoke memory responses. Knowledge like this will help to improve forage grasses breeding and cultivar selection for poorly drained soils.