Effect of preplant seed conditioning treatment on the germination of switchgrass (Panicum virgatum L.)

Switchgrass (Panicum virgatum. L.) is being developed and evaluated as summ er forage and for biomass production in eastern Canada. Uneven germination and slow seedling growth in spring are some of the factors limiting its cul tivation. A study was conducted to reduce seed dormancy and to improve germ ination at suboptimal temperatures in switchgrass cultivars Cave-in-Rock (C IR), Dakota (DK) and New Jersey 50 (NJ). Seeds of these cultivars were cond itioned either with 0.2% potassium nitrate (KNO3) or 1 mM gibberellic acid or osmoconditioned with polyethylene glycol 8000 (PEG) solution with or wit hout 0.2% KNO3 or 1 mM gibberellic acid (GA(3)); or matriconditioned with M icro-Gel E (MC) with either water, 0.2% KNO3 or 1 mM GA(3). The seeds were conditioned at 8 or 16 degrees C for 4 days and then germinated at 8, 16 or 24 degrees C. Conditioning treatment and temperature influenced germinatio n. For CIR seeds germinated at 8 degrees C, conditioning with PEG at 8 degr ees C increased germination from 0 (control) to 22%. All the conditioning t reatments germinated earlier and the proportion of seeds that eventually ge rminated was higher than for the unconditioned control. In the cultivar NJ conditioning at 16 degrees C with water or 1 mM GA(3) increased germination to 12 and 17% respectively (0 for the control) when seeds were germinated at 80C. When germinated at 16 degrees C treatments containing 1 mM GA, germ inated earlier. Osmoconditioning in PEG with 1 mM CA, had the highest final germination at 56% (37% for control). Cultivar DK did not significantly re spond to the various conditioning treatments. Overall, both osmoconditionin g and matriconditioning hastened germination and total germination in switc hgrass cultivars CIR and NJ.