Seed germination and seedling survival of C3 and C4 grasses under water stress

Seed germination and seedling survival of warm-season C4 grasses (Andropogon scoparius, Bouteloua curtipendula, and B. gracilis), and cool-season C3 species (Agropyron dasystachyum, A. desertorum, A. smithii, Elymus angustus and E. junceus) were studied under a range of water stress and temperature treatments in the laboratory. Total germination percentage and germination rate dropped as water potential was decreased from 0•0 to -1•5MPa. Bouteloua gracilis (C4) had significantly higher total germination and germination rate than all species under high temperature (30°C) and water stress, but had the lowest seedling survival when exposed to water stress after germination. Elymus junceus (C3) was more tolerant of high temperature and water stress than all other species except B. gracilis, and also germinated relatively well under water stress at low temperatures. When compared to C4 species, C3 grasses had larger seeds and produced more vigorous seedlings which were better able to survive water stress. In general, seedling survival under water stress was not directly related to the ability of seeds to germinate under stress