© 1997 Heron Publishing—Victoria, Canada
Genotypic variation in drought tolerance of poplar in relation to abscisic acid
Shaoliang Chen (1), Shasheng Wang (1, 2), Arie Altman (3) and Aloys Hüttermann (4)
1. Experimental Center of Forest Biology, Beijing Forestry University, Beijing, 100083, China / 2. Author to whom correspondence should be addressed / 3. The Otto Warburg Center For Biotechnology in Agriculture, The Hebrew University of Jerusalem, Rehovot 76-100, Israel / 4. Forest Botanical Institute, Göttingen University, Busgenweg 2, 37077, Göttingen, Germany / Received October 23, 1996
Summary
We investigated effects of water stress and external abscisic acid (ABA) supply on shoot growth, stomatal conductance and
water status in 1-year-old cuttings of a drought-sensitive poplar genotype Populus × euramericana cv. I-214 (Italica) and a drought-tolerant genotype P. ‘popularis 35-44’ (popularis). Populus popularis was more productive and maintained higher leaf water potentials throughout the drought treatment than cv. Italica. Supply
of ABA to the xylem sap caused a greater decline in growth and more leaf abscission in shoots of cv. Italica than in shoots
of P. popularis. Immediately after initiation of the drought treatment in P. popularis, the ABA concentration ([ABA]) of the xylem increased rapidly and stomatal conductance declined; however, stomatal conductance
had returned to control values by the third day of the drought treatment, coincident with a gradual decline in xylem [ABA].
In contrast, xylem [ABA] of cv. Italica initially increased more slowly than that of P. popularis in response to the drought treatment, but the increase continued for 3 days at which time a tenfold increase in xylem [ABA]
was observed that was followed by abscission of more than 40% of the leaves. We conclude that sensitivity of poplar roots
to variation in soil water content varies by clone and that a rapid short-term accumulation of ABA in shoots in response to
water stress may contribute to drought tolerance.
Keywords:
ABA, plant water status, Populus popularis, shoot growth, stomatal conductance, water stress.
