Variability among Festuca arundinacea cultivars for tolerance to and recovery from waterlogging, salinity and their combination

Abstract

Frequency and intensity of floods and the extent of salt-affected lands are expected to increase in pastures and grassland ecosystems as a result of global climate change. This study evaluated the effects of waterlogging, salinity (150 mm NaCl, ∼15 dS m-1) and their combination over 14 days of treatment on morphological and growth traits of seven cultivars of Festuca arundinacea (tall fescue). Recovery was also assessed after a 14-day growth period under aerated, non-saline conditions (recovery phase). All cultivars survived the imposed stresses, showing greater tolerance to waterlogging than to salinity or the combined stress, evaluated as a response ratio of total dry mass relative to the control. The combined stress provoked growth lower than predicted by a multiplicative model in one cultivar, growth equal to the model in three cultivars and growth higher than the model in three cultivars. High variability among cultivars in response to each stress and phase was observed; this was more evident for relative growth rate of roots than of shoots. Plant morphological traits were affected by treatments in different ways; mature tiller weight was maintained, and tiller number decreased by 79-71% under waterlogging and combined stresses, whereas the opposite responses occurred under salinity. During the recovery phase, plants in all stress treatments had lower tiller numbers than controls and prioritised the growth of pre-existing tillers, which were heavier. Number of dead leaves per plant increased in saline and combined treatments. In general, F. arundinacea proved more tolerant to waterlogging than to salinity or combined treatments, and showed promising variability among cultivars with respect to root relative growth rate under the evaluated stresses, which can be used in future breeding programs. The findings also provide a basis for further research into the tolerance mechanisms involved.