The effect of date and method of lifting on ethylene production by 1-0 loblolly pine (Pinus taeda L.) seedlings during cold storage, the dose-response relationship between ethylene and loblolly pine seedlings during cold storage, and the effect of water stress on ethylene and aminocyclopropane-1-carboxylic acid (ACC) production in two half-sib loblolly families were investigated. Seedlings stored in Kraft-Polvethvlene (K-P) bags showed a general trend of increasing ethylene concentrations from November through February, with an abrupt drop in March. Production rates may be related to the level of dormancy of the seedlings, with the peak in production corresponding to fulfillment of the chilling requirement. Ethylene concentrations within the K-P bags generally declined over the twelve weeks in cold storage. Roots produced significantly higher levels of ethylene while stored in the K-P bags; however, when incubated under light, the needles produced higher concentrations. Roots of machine-lifted seedlings produced significantly higher levels of ethylene than roots of hand-lifted seedlings. However, rates tended to moderate during storage and differences in production between HL and ML whole seedlings were not significant, which suggests that mechanical lifting is not a source of increased ethylene production. A dose-response study indicated that ethylene fumigation during cold storage tended to slightly enhance growth of outplanted seedlings. The effects of water stress on a Virginia Coastal Plain (CP) and an East Texas Drought Hardy (DH) loblolly family were also investigated. Ethylene production during severe stress (-2.8 MPa) appeared to be related to drought hardiness, with the CP seedlings producing much higher levels. Roots of both families produced greater levels of ethylene than the needles and may be due to an enhanced ability to convert 1-Aminocyclopropane-1-carboxylic acid (ACC) to ethylene. / Master of Science