Grass seed germinability declines linearly with increased exposure to in vivo and in virto digestions, but the factors that regulate loss of seed germinability are unknown. One potential mechanism of seed dispersal is seed dormancy. A laboratory study at Texas A & M hypothesized that 'Selection 75' kleingrass (Panicum coloratum) seed with a high level of post-dormancy would withstand the negative effects of digestion better then TEM-LD1 kleingrass seed with a low level of post-harvest dormancy. When germinated immediately following digestion, Selection 75 seed maintained most of its dormancy and germinated poorer than TEM-LD1 kleingrass seed. Seed of TEM-LD1 digested for 48 or 72 hours and then stored for 6 to 8 months, germinated 15 to 25 percentage units poorer than similarly digested seed without storage. They concluded that post-harvest seed dormancy of kleingrass is not an effective mechanism for maintaining viability of seeds when passed through the digestive system of cattle; however, such dormancy probably is a factor in maintaining seed viability after it is excreted.
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