© 1988 Heron Publishing—Victoria, Canada
Differential physiological and morphological responses of two hybrid Populus clones to water stress
Stefano Mazzoleni (1, 2) and Donald I. Dickmann (1, 3)
1. Department of Forestry, Michigan State University, East Lansing, MI 48824-1222, USA / 2. University of Naples, Naples, Italy / 3. Author to whom correspondence should be addressed / Received August 17, 1987
Summary
Hardwood cuttings of Populus clones Tristis #1 and Eugenei were grown in pots in a controlled environment chamber to observe early patterns of growth
and water relations in response to changing conditions of water stress. Height and dry weight growth, dry matter partitioning,
leaf area production, stomatal conductance and leaf water potential were measured periodically during the 73-day experiment.
The two clones reacted in a similar way to an initial period of stress, showing reduced growth, stomatal conductance and leaf
water potential. However, when stress was interrupted by ample watering and then reimposed, substantial differences between
the clones were evident. Growth of Eugenei fully recovered after stress was relieved, especially leaf growth, but when water
deficiency was reimposed, the plants wilted and some leaves died. Tristis #1, in contrast, showed a greater adaptation to
changing stress conditions; it grew less than Eugenei after drought was interrupted, but showed little adverse effect of renewed
water deficits. These responses were partially explained by the higher root/leaf weight ratios of Tristis #1 which enabled
it to maintain a more favorable plant water status than Eugenei.
