April 2022 - 16
Slides at the Idaho Potato Conference presentation on smoke and heat effects on potato plants detail how timing of the events can
disrupt various stages of tuber development and growth.
has increased by 1.5°F since 1920. It
is projected to increase by 2°F in the
2020s, 3.2°F by the 2040s and 5.3°F by
the 2080s. The USFWS model also
projects wetter autumns and drier
summers during the same time period.
Thornton said the 2021 growing
season wasn't just " unusually hot, " it
was " unusually hot early. "
Heat stress during tuber initiation is
particularly impactful on potato plants.
If stress occurs prior to tuber initiation
the plant will often not develop tubers
but instead will continue growing a
greater canopy of leaves.
In 2020, the first 90-degree days
occurred in mid-July. Last year, the
first 90-degree day was June 3.
" The timing of the stress in terms
of whether or not you have tubers
when the stress sets or you don't have
tubers is really critical and that's one
of the things we saw this year (2021), "
Heat impacts potato plants in three
* Delaying or affecting the duration
* Affecting the plant's efficiency of
* Affecting the tubers' external quality.
If tuber initiation is delayed 20 to
30 days due to early season heat stress,
tubers may not have enough time left
in the season to bulk up.
" We start getting into September, days
start getting shorter and we don't have
the light available for photosynthesis, "
Thornton said. " Temperatures go down
and get too cold and (then) we have
things like plant senescence. "
Heat stress after tuber initiation
can impact the efficiency of tuber
development in the face of continued
high temperatures. Prolonged heat
stress leads to vine growth over tuber
growth, Thornton said.
Another important component in
tuber development is soil temperature.
If the plant's row canopy has yet to close,
tubers may develop internal defects
when soil temperatures get above 70°F.
" So, it comes back to management, "
Thornton said. " Anything that delays
emergence, anything that gives you
a spotty stand, anything that delays
early development of the crop -
if you have herbicide damage, if you
have a nutrient deficiency, if you
have rhizoc early in the season -
that's going to affect the plant's
ability to produce enough cover
to shade that soil and reduce soil
" If you have (that) and heat, that's a
really bad combination. "
The impact of heat on tuber
development is greatly diminished
if your plants can reach mid-bulking
prior to heat stress.
" If we can get into mid-bulking
when the tubers are about the size of
a hen's egg, heat after that is much less
damaging, " Thornton said. " It's that
early development from just when the
stolons swell to when the tubers get
up to about quarter size is really the
critical time. "
Table of Contents for the Digital Edition of April 2022
April 2022 - 1
April 2022 - 2
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