Measuring water stress in Eucalyptus grandis Hill ex Maiden seedlings planted into pots

A pot trial incorporating various watering regimes was initiated to assess: 1) water stress in Eucalyptus grandis seedlings, and 2) the efficacy of different types of research equipment in quantifying these levels of water stress for applied research. There were two dry soil treatments differing in terms of seedling root plug moisture at transplanting, dry (DD) and wet (WD), respectively, and three treatments consisting of well watered seedlings transplanted into wet soil (WWD, WWW and control). Treatment WWW was re-watered when seedlings were water stressed. The control was maintained at field capacity for the entire trial period. Seedling physiology was assessed by shoot water potential, stomatal conductance and chlorophyll fluorescence. Seedlings with dry root plugs, planted into dry soil were dead one to two days after planting. A wet root plug at the time of transplanting increased seedling shoot water potential and survival for up to three days in dry soil. Planting into wet soil increased shoot water potential for the duration of the trial and was also associated with new root growth. This study indicated that both the pressure chamber and the porometer provided simple and easy to interpret measures of water stress in E. grandis seedlings. Measurements of chlorophyll fluorescence did not significantly reflect treatment effects.