Agriculture Reference
In-Depth Information
In an effort to prevent planter skips and to
optimize planter performance, growers should
routinely maintain the planter, follow the planter,
uncover planted potatoes, and assess accuracy.
Through a simple visual assessment, one can de-
termine whether or not a planter is functioning
as it should. If operators experience poor planter
performance, they should adjust tractor speed,
check for mechanical issues, make sure hopper
seed levels are adequate, etc., until performance
improves. If performance does not improve, growers
should contact the manufacturer for assistance
or assess different planter makes and models.
and plant growth and development managed to
optimize tuber yield, size profile, and postharvest
quality.
Potato water use
Irrigation is used extensively to optimize potato
growth. Proper irrigation timing and rate are
important to tuber yield and quality (Ojala
et al
.,
1990). Lack of soil moisture may reduce tuber
yield and quality (Shock
et al
., 1992), as may
excessive moisture (Holder and Cary, 1984).
Nelson and Hwang (1975) characterized plant
water use at four individual potato growth
stages: emergence to tuber initiation; the transi-
tion from tuber initiation to tuber bulking; tuber
bulking; and senescence/tuber ripening. From
emergence to tuber initiation, they indicated
that young plants retained a high percentage of
moisture and that water use was high; foliage
growth and water use were significantly correl-
ated. As plants transitioned out of tuber initi-
ation, they held less moisture and their water
use peaked and leveled off. As growth shifted
from canopy to tubers (tuber bulking), both
water use and moisture retention remained con-
stant, but declined as plants senesced (Nelson
and Hwang, 1975).
6.12
Planting Operations and
Post-Planting Tillage
To minimize tractor passes and optimize the place-
ment and effectiveness of fertilizers, pesticides, and
fungicides, growers may utilize the planting op-
eration to apply liquid or granular products in-
furrow and/or in a band within or on the ridge.
During planting, growers have the option to place
seed tubers at their final depth into a ridge of final
shape, or to plant tubers shallow with the intention
of enlarging and shaping the ridge later in the sea-
son. Because sprouts are likely to emerge more rap-
idly from shallow-planted seed, growers in some
regions may choose initially to plant shallow and
then to enlarge the ridge, after the plant emerges,
with one or more tillage or ridging (hilling) oper-
ations. Ridging or re-ridging is conducted to
hasten plant growth, incorporate herbicides and
fertilizers, disrupt weeds, and provide enough soil
for expanding tubers. In wet regions, seed tubers
are often positioned high in the ridge, well above
the furrow, to reduce the rot potential from
standing or draining water. Some commercial op-
erations choose to “drag off ” the top of the ridge
after planting and before emergence to reduce seed
piece depth and disrupt weeds. Once sprouts
emerge from the soil, the dragged-off rows are
shaped and enlarged via a hilling operation.
Water stress and overabundance
Water stress before tuber initiation may lead to a
reduction in tuber number (van Loon, 1981). It
may also affect fry and chip color. Shock
et al
.
(1992) found that drought stress during tuber
initiation improved postharvest fry/chip color;
Iritani and Weller (1973) suggested the opposite.
Shock
et al
. (1992) indicated the difference
between the two studies might have more to do
with the definition of “tuber initiation” than with
differences in potato physiology. They further
explained that if they widened the tuber initi-
ation window to include late-developing tubers
(end of June), then indeed, water stress might
cause dark (stem-end) fries. Shock
et al
. (1993)
supported this claim by imposing water stress on
two varieties during late June and early July. Fol-
lowing harvest, both cultivars produced dark
stem-end fries (also known as “sugar ends”) due
6.13 Growing and
Harvesting the Crop
Once the potato sprouts emerge from the soil,
cultural management decisions must be made
