It is a normal that seeds of Setaria italica are dormant after ripening. You may try five day stratification at -20°C to break down the seed dormancy. I wish you luck.
you can use soaking process to stimulate germination. you can try soaking in giberellic acid at room temperature or in fridge with different concentration. also, try soaking in humic acids. The article that published about celery present on my account on research gate and soaking cicer in giberellic acid may benifit you about the concentration used to induce germination.The following abstract may good for you.
Abstract
Dormancy is the temporary failure of a seed to complete germination under favorable conditions. It allows for the dispersal of seeds in space and time. There are several types of dormancy, which include physical, mechanical, or chemical inhibition by the covering layers of the embryo, the inability to germinate because of an undifferentiated or immature embryo, and the repression of germination by metabolic restraints. The breaking of dormancy is governed by environmental cues, including temperature, light, nitrate, and some smoke components. This allows seedling establishment during suitable conditions to maximize survival. The breaking of physiological dormancy and the induction of germination are regulated via hormone signaling pathways and mainly through the GA- (gibberellin) and ABA-(abscisic acid) biosynthetic and catabolic pathways. The ABA–GA balance appears to be a central regulatory feature that integrates multiple interactions among environmental cues.
An Australian group discovered that smokewater can be a useful tool to germinate difficult seeds. (It can also be a good way to reduce the weed burden in soils as it has been found to cause almost everything to germinate better. Apply, wait for germination, destroy weeds)
I drew up a picture a while back for someone else. The pipe inside the bottom has an number of fine holes along both sides to bubble the smoke through the water. The pipe in the lid only just enters the lid so it cannot suck water only smoky air. An old vacuum cleaner will do the job. Light a smoky fire, ideally with the leaves of the plant you want to germinate but anything will do. Turn on the vacuum for 10/15 mins. You would then need to boil the water to make it sterile.
Breaking Dormancy in Seeds of Pearl Millet, Pennisetum typhoides1
Glenn W. Burton2
Abstract
Seeds of most pearl millet, Pennisetum typholdes (Burm.) Stapf and C.E. Hubb., genotypes are partially dormant for several weeks after harvest. Storage in airtight containers at 0 to 6 C extended the dormancy period in such seeds to more than 12 months.Soaks in water solutions of the following chemicals listed in order of decreasing effectiveness improved the germination of partially dormant pearl millet seed: 2-chlorocthanol, hydrogen peroxide, sodium hypochlorite, potassium nitrate, sulfuric acid, potassium salt of gibberellic acid, and kinetin. A 1-hour soak in a water solution of 1% 2-chloroethanol plus 0.5% sodium hypochlorite increased the germination of dormant pearl millet seeds significantly more than any other chemical without reducing the germination of any genotype tested.
a soak for 24hrs in GA3 at 500-1000 ppm should work , light is required for the seed to germinate after soaking so do not cover the seed. Alternatively try a 24hr soak in KNO3 at 5000 ppm sometimes that works . Urea has also been used to promote seed germination . In all cases expose to light after soaking . Germinate under mist if you can as that will speed things along as well. Finally in some grasses seed that has been held dry and not refrigerated for two years often germinates better than seed that has not been stored sufficiently . I do not know why this is but I know it happens .