Foliar application of plant growth regulators did not
consistently affect tuber skin color difference in blue/purple
skinned cultivars (Table 4). In 2010, ‘All Blue’ tubers treated with LPE were slightly more purple, darker, with com-
parable saturation than control tubers at harvest, although
this slight alteration was not retained after post-harvest
storage. 2,4-D and NAA treated ‘All Blue’ tubers’ surface
color became less vivid and shifted away from the red axis (overall less purple than control) and towards the yellow
axis, after storage in 2009. In 2010, ‘Purple Pelisse’ tubers
treated with NAA and LPE were lighter and further away
from the red axis, with similar saturation to that of control
tubers at harvest.
Foliar application of plant growth regulators also did not
consistently affect tuber skin color difference in yellow
skinned cultivars. No ‘Yukon Gem’ tubers exhibited ΔE*ab
value greater than 1.0 between the growth regulator treatments and corresponding control tubers at harvest or after
post-harvest storage. At harvest, ‘Bintje’ tubers from 2,4-D
treated plants had higher yellow saturation than control
tubers, though this was not the case following storage.
‘Bintje’ tubers from LPE treated plants were also slightly
darker and less vivid than the control following storage in
2009.
Overall, post-harvest storage appreciably altered tuber
surface color for each of the six cultivars, when contrasted
with corresponding control tubers at harvest (Table 4;
ΔE*ab HS values ranging from 3.4 to 7.1).