Seasonal and diurnal changes in water balance of fruits, cones, and leaves of forest trees
Seasonal variations in actual moisture content (MC), moisture content as percent of dry weight (% MC), and dry weight were determined for fruits of Acer rubrum L., Quercus rubra L., and Prunus serotina Ehrb. at weekly or 2-weekly intervals. On selected dates diurnal variations in MC, % MC, and dry weight of fruits or cones and leaves of Quercus rubra, Prunus serotina, P. virginiana L., and Pinus banksiana Lamb. were determined at 4-hour intervals during the day and night. Percentage moisture content of reproductive tissues and leaves was variously influenced by water uptake or loss, change in dry weight, or both of these. The water balance of different tissues of the same organ varied differently, both seasonally and diurnally, in the same species as well as between species. Percentage moisture content alone is not an accurate indicator of internal water balance of plants and should be interpreted in relation to both water weight and dry weight changes of tissues.