Germination Responses of Purpletop and Big Bluestem Caryopses Subjected to Prechilling, Sodium Hypochlorite, and Storage

Degraded meadow may be restored by sowing native seed mixes.  Establishment of native plants into an area may benefit the restoration process by increasing animal habitat in restored zones.  Slow germination and/or poor stand establishment following seeding of purpletop (Tridens flavus) and big bluestem (Andropogon gerardii) may limit the use of these warm-season grasses native to the United States.  This study evaluated (1) caryopsis prechilling (presowing chilling) with distilled water (dH₂O);  (2) prechilling with potassium nitrate (KNO₃); (3) soaking in 10% chlorine bleach (v/v; 0.6% NaOCl); and (4) storage conditions following seed treatments.  Prechilling of ‘VA Ecotype’ purpletop  and ‘Niagara, NY Ecotype’ big bluestem  increased final germination percentage (FGP) and germination rate, compared to nontreated caryopses (control), following 7 or 14 days at 5 ^oC in dH₂0 or 0.2% KNO₃ for purpletop and following 7 days at 5 ^oC in dH₂O for big bluestem.  Germination synchrony increased following prechilling of purpletop but not for big bluestem.  Determinations using slant tests indicated that storing prechilled and dried-back purpletop caryopses for 10 days at 5 ^oC reduced FGP and shoot lengths in comparison to moist-stored caryopses.  Sowing prechilled, moist-nonstored purpletop caryopses resulted in greater FGP and shoot and root lengths than other seed treatment combinations or nontreated caryopses.  Seedlings from prechilled caryopses of big bluestem moist-stored for 10 days at 21 ^oC had reduced root lengths in comparison to dried-back, stored caryopses.  NaOCl treatments resulted in reduced FGP and root lengths for stored purpletop but had little or no effect on big bluestem.  Greenhouse trials indicated stand establishment increased four weeks after sowing prechilled caryopses compared to nontreated caryopses; however, sowing of prechilled or nontreated big bluestem caryopses resulted in similar stand establishment.