Manipulating Loblolly Pine (Pinus Taeda L.) Seed Germination with Simulated Moisture and Temperature Stress

Abstract

Temperature and available moisture are environmental variables with substantial control over seed germination. Speed and completeness of germination in loblolly pine (Pinus taeda) seed strongly influence seedling yields. The impact of moisture and temperature on loblolly seed performance was investigated by germinating seed at temperatures cycling between optimal (21°C) and stressful (13°C or 35°C) or in the presence of osmotically simulated moisture stress ranging between -300 kPa and -1500 kPa. The rate of germination was significantly reduced by exposure to the low temperature treatment. Any level of osmotically induced moisture stress decreased the rate and, ultimately, total germination. The impact of temperature or moisture stress was partially mitigated by increasing the stratification interval prior to germination. Consequently, low temperatures and/or decreased availability of moisture represent potential environmental restrictions on crop establishment and subsequent seedling yields. Germination patterns of seed experiencing environmental stress can be improved by extending the interval of stratification prior to sowing.