Emergence and Seedling Survival of Two Warm-Season Grasses as Influenced by the Timing of Precipitation: A Greenhouse Study

A greenhouse study was conducted to determine seedling survival probabilities of sideoats grama (Bouteloua curtipendula (Mich x.) Torr.) and cochise lovegrass (Eragrostis lehmanniana Nees × Eragrostis trichophora Coss & Dur.) for selected combinations of initial wet-day and dry-day sequences. Three separate 14-day experiments were conducted using 1, 2, 3, 4, and 5 days wet followed with 5 days dry. The number of emerging seedlings growing from 10 seeds placed in a sand media in small plastic cones were counted daily. A total of 50 to 70% of the sideoats grama seeds emerged in the initial wet period, but over 50% of the seedlings died in the following 5-day dry period, resulting in less than a 35% survival rate. The cochise lovegrass was slower to germinate and less susceptible to the effect of the 5-day dry period, which resulted in 40 to 60% seedling survival. With the 1- and 2-day wet sequences, the maximum cochise lovegrass plant count was not achieved until the final rewet period. With the exception of 5 days wet, the length of the initial wet period did not significantly affect the number of surviving lovegrass seedlings. This information offers the possibility of incorporating the probablistic aspects of precipitation and soil water relations into a description of the seedling environment.