Germination of Liatris spicata (L.) Willd. Seed Is Enhanced by Stratification, Benzyladenine, or Thiourea but not Gibberellic Acid

The effects of stratification, BA, thiourea, and GA3 were examined on germination of Liatris spicata (L.) Willd. seed. Seeds were germinated at 20 °C and numbers of germinated seed were counted daily for 21 days. The final germination percentage (G) for seeds stored dry at 4 °C for 0 to 10 weeks ranged from 52% to 64%, while stratification at 4 °C for 10 weeks increased G to 98% and decreased the days to 50% of final germination (T50) and the days between 10% and 90% germination (T90-T10). Aqueous solutions of BA at 10 or 100 mg·L-1 applied to blotter paper increased G and decreased T50 but did not affect T90-T10. In a separate experiment, dry seeds were treated for 3 minutes in BA at 0 to 1126 mg·L-1 dissolved in acetone. G values increased quadratically, whereas T50 and T90-T10 values decreased quadratically in response to BA concentration. A 3-minute preplant acetone permeation of seeds with BA at 225 or 1127 mg·L-1 yielded G and T50 values similar to those obtained with 10 weeks of stratification. Seeds immersed in thiourea at 0.76 or 7.61 mg·L-1 for 24 hours prior to sowing had higher G and lower T50 values than controls (0 mg·L-1 thiourea), but T90-T10 values were similar for all treatments. Seeds treated with GA3 at 1, 10, or 100 mg·L-1 in H2O did not differ from controls (0 mg·L-1 GA3) in G, T50, or T90-T10. Infusion of BA via acetone may be a practical means of breaking seed dormancy and accelerating germination in L. spicata. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)]; gibberellic acid (GA3); thiocarbamide (thiourea).