|Abstract or Summary
- The objective of this study was to develop a soaking and drying
procedure to stimulate faster germination of Kentucky bluegrass (Poa
pratensis L.) seed.
The seeds were soaked in cheesecloth bags in nine chemical
solutions. The effects of temperature and time of soaking and of
aeration of the solution were studied. The most beneficial results
were obtained when the seeds were soaked at 5°C for 6 days in an
aerated KNO₃ solution. Following the soaking period, the seeds were
air-dried for 24 hours at room temperature to return them to a
moisture content of approximately 10%.
The effects of presoaking were evaluated in terms of speed of
germination, percent germination, maximum and minimum germination
temperatures, alternating temperature requirements, drought
resistance, soil emergence and storability.
Soaking in a complete nutrient solution, 200 ppm GA₃ and
2.3 ppm benzyl adenine also gave better results than unsoaked controls.
Succinic acid, thiourea, hydrogen peroxide, sodium hypochlorite
and water had no stimulating effects. Shorter and longer
soaking periods and temperatures of 20° and 5-25°C were less beneficial.
Presoaked seeds started to germinate 1 to 2 days earlier,
reached the peak of germination 2 to 3 days earlier and frequently had
a higher germination percentage than the control. Presoaking allowed
the seeds to germinate at a minimum temperature 3°C below and a
maximum temperature 4°C above that of the control. The requirement
for alternating temperatures was also reduced.
The beneficial effects of the treatments were more obvious
under a stress germination temperature of 25° C than at the more
The ability to germinate under moisture stress conditions was
improved by presoaking. The relative advantage in favor of the presoaked
seeds increased as the osmotic pressure of the germination
Even though the difference was not statistically significant,
presoaked seeds emerged faster and had higher percent germination
20 days after planting in greenhouse soil. When soil was used as the
germination media, seeds presoaked in water performed better than seeds presoaked in KNO₃.
Cultivars responded differently to the treatments. Merion, the
cultivar which was hardest to germinate in the laboratory, was not
affected by the treatments. Less dormant cultivars such as Cougar,
Park and Newport were stimulated more than the more dormant
Pennstar, Fylking and Windsor.
A germination test conducted after 4 months of storage indicated
that the beneficial effects of the treatments were irreversible.
Viability of the treated seeds was retained after 7 months of storage at
Presoaking increased the germination speed to a greater degree
than the after-ripening which took place during 7 months of storage at
Humid storage accelerated germination but dry storage at 40°C