Leaf roll of tomato caused by accumulation of carbohydrate

Material Information

Leaf roll of tomato caused by accumulation of carbohydrate
Series Title:
Bradenton AREC research report
Woltz, S. S
Agricultural Research & Education Center (Bradenton, Fla.)
Place of Publication:
Bradenton Fla
Agricultural Research & Education Center, IFAS, University of Florida
Publication Date:
Physical Description:
2 leaves : ; 28 cm.


Subjects / Keywords:
Tomatoes -- Growth -- Florida ( lcsh )
Tomatoes -- Diseases and pests -- Florida ( lcsh )
Carbohydrates -- Physiological effect ( lcsh )
Tomatoes ( jstor )
Dietary carbohydrates ( jstor )
Insects ( jstor )
government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )


General Note:
Caption title.
General Note:
"May 1973."
Florida Historical Agriculture and Rural Life
Statement of Responsibility:
S.S. Woltz.

Record Information

Source Institution:
Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location:
Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management:
All rights reserved, Board of Trustees of the University of Florida
Resource Identifier:
71843445 ( OCLC )


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represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
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site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida

([ / IFAS, I- v' iyn-' 4-gily r Pa -
irar'cnon AREC Research Report C1973-5 May 1973
I- MAY 16 1973

I.FsA.S- ithim of Florida

Tomato plants growing under routine culture frequently have a characteristic
leaf roll varying from mild to severe. Lower leaves are first to roll, followed
by a gradual development of leaf roll toward the top of the plant. Margins of
leaves roll upward and inward. In mild cases, leaves become trough shaped, whereas
in severe cases the leaf may turn yellow and form a tight spindle. The severity of
leaf roll varies with climatic conditions, cultural practices and varieties. High
light intensity predisposes to the disorder. When leaf roll is severe, fruits are
exposed to full sunlight which may result in the development of disorders such as
sun scald. Sun scald is not usually severe unless leaf roll develops rapidly
ca-.3ng exposure of fruit to full sunlight without a gradual physiological adjust-
ment. An excessive tendency toward the disorder may result in the discarding of
a breeding line or in the lack of acceptance of a tomato variety in the areas
where leaf roll is severe. For example, varieties which will grow "normally" in
areas where light intensity is significantly decreased by air pollution and cloudi-
ness may be rejected in variety trials in Florida because of excessive leaf roll.
With cultural methods involving mechanical harvesting, however, leaf roll may be
beneficial due to ease of removal of fruit from the vine.

Observations were made during the course of an experiment, unrelated to leaf
roll, that the removal of flower hands, fruit or young vegetative shoots caused a
rapid and severe leaf roll beginning at the bottom of the plant and extending to
the top in one week's time. It was postulated that the accumulation of sugars
and starch reached such a high level that cell physiology was adversely affected.
Several experimental procedures were used to test this theory: (1) removal of the
parts of the plants that normally assimilate the carbohydrate from mature leaves
resulted in leaf roll, yellowing and thickening of leaves all symptoms of
physiological leaf roll; (2) healthy leaves were removed from plants and stems
placed in containers of solutions with increasing sugar content increasing sugar
increased yellowing, caused moderate leaf roll and a decrease in measured photo-
synthetic capacity, and (3) tomato plants were grown under 0, 25, 50 and 75%
shade to determine effects on leaf roll and corresponding carbohydrate accumulation.
Increasing shade decreased leaf roll, yellowing and carbohydrate accumulation, all
measured in lower leaves. When shaded plants were later exposed to full sunlight,
they developed leaf roll in a short period of time. Observations in field-grown
tomatoes indicated that leaves on the sunny side of the row were subject to leaf
roll while those on the shaded side (North in the fall season) were not rolled.
Apparently, direct solar radiation increased photosynthesis above the capacity
of the leaves to export the manufactured carbohydrate.

Magnesium deficiency was observed to cause the symptoms of leaf roll asso-
ciated with high foliar carbohydrate content. Consequently, magnesium deficiency
was produced experimentally in graded degrees of severity and data were taken on
leaf roll and carbohydrate accumulation. Increasing severity of deficiency


increased the occurrence of.typical leaf roll and also increased foliar carbohy-
drate content. Fruit carbohydrates were, conversely, decreased indicating that
magnesium is essential for the transport of sucrose (the common chemical form
for carbohydrate transport) to the tomato fruit. Magnesium is essential to the
activation of the enzyme for sucrose manufacture.

Leaf roll is related to nitrogen nutrition. It is made worse by nitrogen
deficiency and alleviated when adequate nitrogen is available to combine with
carbohydrate in protein manufacture. The nitrate form of nitrogen corrects leaf
roll better than the ammoniacal form. Conditions that interfere with protein
synthesis similarly accentuate leaf roll. Virus diseases such as pseudocurly
top of tomato and virus leaf roll of potato cause leaf roll symptoms apparently
by seriously limiting the rate of protein synthesis. Chemicals such as ANCPA
(l-amino-2-nitro cyclopentane-l-carboxylic acid) manufactured by the fungus
Aspergillus wentii inhibit protein synthesis strongly and cause leaf roll. Chem-
icals of this type that are produced by soil microorganisms may affect tomato
as well as other plants but have not been found to be a problem in Florida tomato

Tomato leaf roll seen in the field can be attributed partly to the practice
of pruning. The tomato plant is capable of producing much greater amounts of
foliage and fruit than found with pruned and staked plants. This cultural prac-
tice therefore causes an accumulation of excess carbohydrate in leaves.

In summary, most of the leaf roll found with tomatoes is not caused by para-
sitic organisms. The condition may be considered a "normal" reaction that develops
under certain cultural practices. There is no need to attempt to prevent it unless
it has been determined that crop production is affected. If leaf roll should be
found to be a production problem, then control procedures could be implemented
based on the discussion of the above causes. Magnesium deficiency should be
considered seriously as a possible causal factor if there is any indication of
a possible shortage or imbalance. Magnesium nutrition may be thrown into a state
of imbalance by excesses of other cations in the soil. It is important that this
be eliminated as a factor for consideration since the symptomatology of leaf roll
due to carbohydrate accumulation and that due to magnesium deficiency are not dis-
tinguishable visually. A slight magnesium deficiency results in mild leaf roll
but a severe deficiency results in severe leaf roll, chlorosis of the leaves,
and stunting and death of the plants. Inadequate or imbalanced nitrogen nutri-
tion (nitrate vs. ammonia) may make leaf roll more severe but the nitrogen effects
are ordinarily considered separately from leaf roll in tomato production practices.