| Material Information
||Daily recutting of stipe affects postharvest vase-life, water uptake, and fresh weight change of leatherleaf fern fronds
||AREC-A research report
||4 p. : ; 28 cm.
||Henny, R. J
Fooshee, W. C ( William C. ), 1951-
Agricultural Research and Education Center (Apopka, Fla.)
||University of Florida, IFAS, Agricultural Research and Education Center-Apopka
||Place of Publication:
||Cut foliage -- Postharvest technology -- Florida ( lcsh )
Leatherleaf fern -- Postharvest diseases and injuries -- Control -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
bibliography ( marcgt )
non-fiction ( marcgt )
||Includes bibliographical references (p. 2).
||Statement of Responsibility:
||R.J. Henny and W.C. Fooshee.
||AREC-Apopka research report ;
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Daily Recutting of Stipe Affects Postharves Vase-life, Water Uptak
and Fresh Weight Change of Leather ea.fiFerniF.rodi [c--'i 2
R. J. Henny and W. C. Fooshee
University of Florida, IFAS
Agricultural Research and Education Center Apopka
AREC-A Research Report RH-84-25
Rapid postharvest decline of leatherleaf fern ("commonly called wilt or
curl") is sometimes a serious problem. The cause of fern wilt has not been
determined, although several factors are suspected of influencing its
A previous report indicated that postharvest wilt can be reversed by re-
cutting the base of the stipe of newly wilted fronds before they reach a
permanent state of wilt (1). These results showed that postharvest fern wilt
may be influenced by vascular plugging near the base of the stipe. This study
was conducted to determine the effect of daily recutting of stipes on post-
harvest longevity of leatherleaf fern fronds.
Forty fronds of uniform size were harvested from ground beds under 73%
shade at AREC-Apopka on March 28, 1983. Fronds were taken to an interior
growth room held at 800+2 F, with 12 hours of 200 ft-c fluorescent light per
day. Each frond stipe was recut, using a single-edge razor blade, to a length
of 20 cm below the first basal pinna. Individual fronds were then weighed and
placed in 100 ml graduated cylinders containing deionized water. Twenty
fronds were left intact (controls) during the course of the experiment while
1/2 cm was removed daily from stipes of the other 20 fronds. Cut portions
were weighed and their weights added to the fresh weight of each respective
frond at the end of the experiment. Water uptake (ml) for each frond was
recorded daily. Wilted fronds were weighed and discarded the day wilt
occurred. After 18 days, fresh weight of remaining fronds was taken and the
Fronds which were recut daily had a longer average vase-life (18.0 days)
than those which were not recut (14.5 days). Eleven control fronds (55%)
wilted before the experiment was completed while none of the recut fronds
wilted (Table 1). Uncut fronds lost an average of 18.8% of their original
fresh weight during the course of this experiment. Uncut fronds which wilted
lost an average of 22.9% of their fresh weight, compared to 13.8% for uncut
fronds that did not wilt. In contrast, fronds which were recut daily showed
no fresh weight change. Average daily water uptake per frond was 3.1 ml for
uncut fronds versus 7.1 ml for those recut daily.
Leatherleaf fern fronds, once cut and placed in deionized water,
typically take up large quantities of water during the first 24 hour period
(day-1). During this time water uptake often exceeds 20 ml per frond. Water
uptake abruptly declines during day-2 after harvest (Figure 1). After day-3,
water uptake levels off or declines slightly for the remainder of a'frond's
Associate Professor, Plant Genetics, and Biologist, respectively. Agricul-
tural Research and Education Center 2807 Binion Road, Apopka, FL 32703.
postharvest vase-life. Water uptake during this period is usually in the
range of 1-10% of that taken up in day-1. In some instances, water uptake
ceases totally even though fronds remain turgid and green.
Seemingly, only two phenomena could account for these results: A.
Stomates may gradually close in response to water deficits induced by
separation of the frond from the parent plant; or, B. Plugging of the vascular
system occurs and prevents water uptake even though stomates may remain open.
Data from this experiment indicate that both factors appear to affect water
uptake in cut fern fronds. Greater water uptake in fronds which were recut
daily compared to uncut fronds, indicates that vascular plugging in the basal
1/2 centimeter of the stipe is a barrier to water use. However, the fact that
water uptake in recut fronds never reaches day-1 levels suggests that stomatal
closure is occurring.
In this experiment, greater water uptake in fronds recut daily may be due
to elimination of vascular plugging at the base of the stipe. The difference
between the elevated level and the day-1 level could represent percent of
closed stomates. For example, assuming maximum number of open stomates at
day-1 postharvest, a frond which used 20 ml of water during day-1 but only 4
ml during day-7 after being recut, may have as much as 80% stomatal closure.
If true, data from this experiment indicate that not all stomates have closed
after 18 days postharvest as recutting continued to maintain water uptake.
However, these differences may also be due to plugging of vascular tissue
farther up the stipe and not only progressive closing of stomata. If true,
closing of stomata cannot be accurately determined using the above example.
Unfortunately, it would be a most difficult, if not impossible, task to verify
the degree of vascular plugging throughout the entire frond.
In other studies (Henny & Fooshee, unpublished results), 100% of leather-
leaf fern fronds examined after 24 hours in deionized water showed evidence of
vascular plugging at the cut surface of the stipe. Plugging was clearly
visible in fresh transverse freehand sections of the stipe base. A second
freehand section, adjacent to the basal sample showed no evidence of plugging.
It is probable therefore, that postharvest leatherleaf fern wilt is due to a
combination of vascular plugging and failure of a sufficient number of
stomates to close rapidly in response to subsequent internal water deficits.
Whether or not individual fronds wilt in response to these conditions may be
predetermined by the physiological state of the frond at harvest. Future
studies concerning causes of postharvest leatherleaf fern wilt should
concentrate on the nature of vascular plugging and factors which affect
stomatal activity in cut fronds.
1. Henny, R. J. 1982. Reversing postharvest wilt of leatherleaf fern.
ARC-Apopka Research Report RH-82-23. 2 pp.
2. Nell, T. A., J. E. Barrett and R. H. Stamps. 1983. Water relations and
frond curl of cut leatherleaf fern. 108:516-519.
3. Poole, R. T., C. A. Conover and R. H. Stamps. 1985. Wilt of leatherleaf
fern harvested at various times of the year and frond ages. Proc. Fla.
State Hort. Soc. (In Press).
Table 1. Effect of daily recutting of the stipe on average postharvest vase-
life, amount of wilt, fresh weight change and daily water uptake of
leatherleaf fern fronds. Fronds were either left intact (control) or had
1/2 cm cut from the stipe base daily for 18 days.
Type of observation
Uncut Recut Daily
1. Average Vase-life (days) 14.5 18.0
2. No. wilted fronds 11 0
3. Fresh weight change (%)
wilted fronds -22.9
unwilted fronds -13.8 0
overall average -18.8 0
4. Daily Water Uptake (ml)
1st 6 days 7.1 13.8
2nd 6 days 1.3 4.2
3rd 6 days 0.9 3.2
overall average 3.1 7.
z20 fronds per treatment. Experiment initiated March 28, 1983.
4U 10 \
ago**as. .a am aa a .. a
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Figure 1. Effect of recutting the stipe on average daily water
uptake of harvested leatherleaf fern fronds. Fronds were
either left intact (control) or had 1/2 cm cut from base of