Osmotic measurements in whole megagametophytes and embryos of loblolly pine (Pinus taeda) during seed development

Water potential (Ψ) and osmotic potential (Ψs) were measured weekly through the sequence of seed development in megagametophytes of loblolly pine (Pinus taeda L.). A Wescor 5500XRS vapor pressure osmometer, modified with a cycle hold switch, was used to measure Ψ for whole megagametophytes containing embryos. The Ψ measurements for megagametophytes with embryos removed were also attempted but readings were distorted due to cell lysates from the...