Jc. Clifton-brown et I. Lewandowski, Water use efficiency and biomass partitioning of three different Miscanthus genotypes with limited and unlimited water supply, ANN BOTANY, 86(1), 2000, pp. 191-200
Miscanthus species, which are C-4 perennial grasses, have a high biomass po
tential but yields at many sites in Europe can be limited by insufficient w
ater supply and plant survival is endangered under extreme summer drought.
A pot experiment was conducted to measure the influence of reduced water su
pply on the water use efficiency (WUE) and biomass partitioning of three Mi
scanthus genotypes (M. x giganteus, M. sacchariflorus, and a M. sinensis hy
brid) in a controlled environment. The experiment consisted of three phases
(phase 1 = 0-20 d; phase 2 = 21-39 d; phase 3 = 40-54 d) punctuated by des
tructive harvests. In phase 1, soil moisture was non-limiting. In the secon
d and third phases. lowered soil moisture contents induced water deficits.
Air vapour pressure deficit (VPD) was 0.49 +/- 0.05 kPa. Water deficits cau
sed leaf senescence in M. x giganteus and M. sacchariflorus, but not in the
M. sinensis hybrid. Green leaf conductances were lowest in M, sinensis und
er water deficit, indicating stomatal regulation. Water use efficiency for
whole plants of each genotype ranged from 11.5 to 14.2 g dry matter (DM) kg
(-1) H2O but did not differ significantly between genotypes or water treatm
ents under the conditions of this experiment. However, differences in dry m
atter partitioning to the shoot (the harvestable component) resulted in gen
otypic differences in WUE, calculated on a harvestable dry matter basis, wh
ich ranged from 4.1 g DM kg(-1) H2O for M. sacchariflorus to 22 g DM kg(-1)
H2O for M. x giganteus. (C) 2000 Annals of Botany Company.