Regulating acorn germination and seedling emergence in Quercus pagoda (Raf.) as it relates to natural and artificial regeneration
Dormancy break and germination requirements for Quercus pagoda (Raf.) acorns were determined, as well as the effects of acorn pretreatment and post-germination temperatureson epicotyl emergence, seedling development, and seedling biomass accumulation.There was an inverse linear relationship between length of cold stratification (5/1 °C for0–12 weeks) and cumulative germination percentages in all incubation temperatures (15/6,20/10, 25/15, 30/20 °C). Acorns required 12 weeks of cold stratification to break dormancy.Gibberellic acid substituted for cold stratification; although, it was not as effectiveas 12 weeks cold stratification. At 16 weeks of cold stratification, 20% of acorns hadgerminated, and the remaining 80% of ungerminated acorns reached ≥ 97 ± 1% cumulativegermination within 4 days in all incubation temperatures. Post-germination time to epicotylemergence and to leaf flush was a function of temperature, and time decreased withincreased temperatures. With light held constant (50 μmol m−2 s−1), seedlings accumulatedgreater biomass in temperatures 20/10 °C. Q. pagoda acorns possess Type 2 nondeepphysiological dormancy, and this allows for artificial manipulation of timing and durationof germination. Extending cold stratification 4 weeks beyond dormancy break (i.e.,16 weeks) yields more uniform germination across a range of temperatures. Epicotyl emergence,seedling development, and biomass accumulation may be regulated by manipulatinggrowing temperature. In this study, the most uniform seedling cohort with the greatest totalbiomass was produced when acorns received 16 weeks of cold stratification, followed bytransfer of germinants to 30/20 °C.
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