Jerusalem artichoke genotypes were classified into the group
with high DTI values for root dry weight, root diameter, root: shoot
ratio, root length, root surface area and root volume and the group
with low DTI values for these traits. These Jerusalem artichoke
genotypes were previously identified as drought tolerant varieties
based on tuber yield, but their responses to drought based on root
traits was not investigated. JA 125, JA 5 and JA 60 showed the
highest DTI values for root parameters, and JA 89 and HEL 65
showed the lowest DTI values for root parameters.
JA 89 had the highest root dry weight but it had the lowest DTI
values for root traits under mild water stress and severe water
stress. In this genotype, the contribution of dry matter was partitioned
to vegetative growth rather than harvestable organ. The sink
competition between the harvestable part and the root sink should be considered when devising breeding strategies to improve
drought resistance [25]. JA 125, JA 5 and JA 60 were classified as a
group with high tuber dry weight under mild water stress, and JA 5
was identified as the drought tolerant genotypes under severe
drought stress because it had the highest tuber dry weight under
severe water stress. Some varieties had low means for root parameters
but they had high DTI values for these parameters. The
results indicated that Jerusalem artichoke varieties changed root
growth patterns in response to drought to mine more water from
drying soils, and, therefore, these varieties could maintain high
tuber yield under drought.