Some physiological comparisons between the resurrection grass, Eragrostis nindensis, and the related desiccation-sensitive species, E-curvula

Both the poikilochlorophyllous resurrection grass. Eragrostis nindensis, and the desiccation sensitive species, E. curvula, dehydrate to a relative water content (RWC) of less than 5% in two weeks. On rewatering, most E. nindensis leaves (except the older, outer ones) rehydrate and resume normal metabolic activity within a few days, whereas E. curvula does not recover. There is a controlled loss of photosynthetic pigments, paralleled with a gradual shutdown in gas exchange during dehydration of E. nindensis. On rehydration respiration resumes almost immediately but photosynthesis only restarts at 70% RWC by which time chlorophyll has been resynthesised and anthocyanin content reduced. In contrast, photosynthetic activity in E. curvula is maintained down to 40% RWC, after which further drying results in a sudden breakdown of the photosynthetic system and its pigments. At this point, electrolyte leakage and increases F-V/F-M decreases such that below ca. 40% RWC, metabolism is irreparably damaged. Interestingly, the older outer leaf in most tillers of E. nindensis does not rehydrate. These leaves show signs of membrane damage and curl in an irregular manner similar to those of E. curvula during dehydration.