Scarification and high, diurnal temperatures produce optimal germination of sand dropseed (<i>Sporobolus cryptandrus</i>(Torr.) A. Gray)

Sand dropseed (<i>Sporobolus cryptandrus</i> (Torr.) A. Gray [Poaceae]) is a native, warm-season perennial bunchgrass that has value in conservation seedings in the Intermountain West. US Department of Agriculture, Natural Resources Conservation Service, Aberdeen Plant Materials Center conducted 3 experiments to determine whether seed treatments could improve percent germination and coefficient of germination (CG, germination speed) of various accessions of sand dropseed. The effects of temperature, scarification, cold-moist stratification, and germination in Petri dishes or aerated water baths (bubblers) were investigated in a growth chamber. Initial Petri dish experiments with one accession at optimal germination temperatures indicated that scarification did not increase final percent germination (FPG) at 14 d after initiation (DAI) but did increase CG from 7.9 to 10.4. Scarification did not increase FPG or CG at 28 DAI at suboptimal temperatures. A larger study with 3 accessions and 8 treatment combinations of scarification, stratification, bubblers, and Petri dishes at optimal temperatures found the highest FPG and CG for each accession occurred with scarified seed germinated in Petri dishes. In some cases, stratification alone improved germination, but in other cases, it resulted in lower germination due to fungal growth. For all 3 accessions, germination in Petri dishes was superior to that in bubblers. These results suggest that scarification, and possibly stratification (both of which can be used for field-scale plantings), may improve the success of sand dropseed establishment in conservation seedings.