Agriculture Reference
In-Depth Information
Advancing the start of the growing season
Apart from a shift in partitioning to leaves at the beginning of the growing
season, an early start of radiation interception may also be effected by low
temperature requirements for leaf growth. Temperature requirements of
early leaf development were evaluated in 32 genotypes from the genus
Miscanthus (Clifton-Brown and Jones 1997). In Figure 7.3, plant extension
rates ( i.e. height growth rates) of two contrasting genotypes are shown.
Based on these data, Clifton-Brown and Jones (1997) simulated potential
yields of the 32 genotypes under the climatic conditions in Ireland.
Differences in leaf development rates in spring had large consequences for
the final biomass yield of the different Miscanthus genotypes: simulated
yields ranged from 3 to 23 t d.m. The genotype with the highest yield
(P34) is the M. × giganteus genotype that is already being used in most
field trials in Europe. Therefore, it seems that the genotype with the lowest
temperature requirement for leaf emergence has already been selected, and
that there is little scope for yield increase in this direction.
Diminishing winter losses
Reported stem losses during winter range from 0-50 % (Schwarz et al.
1993; Beale and Long 1995; Jørgensen 1997). In this study, the current
average stem loss is assumed to be 15 %, and is assumed to decrease to 10
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