Agriculture Reference
In-Depth Information
nor affect incidence of the disorder in the sub-
sequent crop.
Tuber growth rate is an important factor
in the development of hollow heart. Rapidly
growing tubers are more likely to develop hol-
low heart. Hollow heart typically appears when
stress conditions affect the plant and reduces
tuber bulking, followed by a relief from the
stress and a rapid increase in tuber bulking
rate, such as when rainfall follows a moisture
deficit. Nelson (1970) observed over a period of
4
years that “hollow heart is particularly ser-
ious when stands are poor, moisture is adequate
or heavy, temperatures are below normal and
plants are vigorous enough to maintain a rapid
rate of tuber growth”. Growing season or year
of production strongly influences the develop-
ment of hollow heart.
Wide plant spacing promotes larger tubers
and favors hollow heart (Rex
et al
., 1987;
Creamer
et al
., 1999). High rates of nitrogen fer-
tilizer especially late in the season promote the
disorder (Wilson
et al
., 2009), while potassium
fertilization tends to reduce hollow heart (Nel-
son, 1970; Panique
et al
., 1997). Nitrogen ap-
plied near tuber initiation may stimulate tuber
growth rate and enhance hollow heart forma-
tion (Hiller and Thornton, 1993). A connection
exists between tuber calcium concentration and
hollow heart. Tubers with non-periderm cal-
cium levels of
100
µg g
−
1
dry weight or less have
a greater incidence of hollow heart (Kleinhenz
et al
., 1999).
Controlling hollow heart and brown center
completely is very difficult, if not impossible.
However, some cultivars are less susceptible to
both conditions and should be chosen in regions
known to exacerbate their formation. Other
than cultivar choice, managing hollow heart
and brown center involves using cultural prac-
tices that promote uniform steady plant and
tuber growth rates and reduced plant stress.
Delay planting to avoid cool soil temperatures at
tuber initiation. Establish uniform plant stands
by planting at the proper depth and spacing.
The use of large seed pieces ensures a good
stand and several stems per hill. Adequate plant
competition and a full tuber set help reduce
periods of rapid tuber growth. Avoid excessive
irrigation and fertilization. Maintain uniform
soil moisture and fertility levels for steady, uni-
form plant growth.
Fig. 14.3.
Hollow heart in Yukon Gold tuber. (Photo
courtesy of S.B. Johnson, University of Maine.)
area. There may be one or more cavities in the
tuber that are transverse or longitudinal to the
pith. The cavity may develop a suberin lining
similar in structure to the periderm, giving it a
tan or dark brown color (Dean
et al
., 1977). De-
pending on when the cavity is formed, it may be
near the center of the tuber or towards the bud
end or stem end. On occasion, fungi or bacteria
invade the cavity and rot the tuber from the
inside (Wale
et al
., 2008).
Cavities formed near the stem end of the
tuber are called stem-end hollow heart. Stem-
end hollow heart is formed early in the grow-
ing season, shortly after tuber initiation, and is
preceded by a brown center (Levitt, 1942). It is
often associated with a period of restricted
growth due to cool soil temperatures, followed
by accelerated growth rates as the soil warms
up. A cavity near the bud end of the tuber is
called bud-end hollow heart. It is not associ-
ated with brown center and is initiated late in
the tuber bulking period. Bud-end hollow
heart is commonly caused by tuber growth
stoppage due to water or nutrient stress late in
the season (Rex and Mazza, 1989). Cultivars
vary in susceptibility to hollow heart (Rex and
Mazza, 1989; Jansky and Thompson, 1990).
Russet Burbank and Yukon Gold are very prone
to hollow heart. Large tubers tend to develop
hollow heart more frequently than smaller
tubers (Nelson and Thoreson, 1986; Jansky
and Thompson, 1990), but hollow heart may
be found in small tubers during a period of ex-
ceptionally rapid growth (Hiller
et al
., 1985).
Hollow heart does not affect seed tuber quality,
