Title page for ETD etd-06102012-040536
|Type of Document
||Long, Robert Sherman
||Influence of nitrogen rate, harvest frequency, lower leaf management, and chemical topping on mammoth cultivars of flue-cured tobacco
||Master of Science
|Jones, James L.
|Johnson, Charles S.
|Wolf, Dale D.
|Date of Defense
Mammoth cultivars of tobacco do not flower under normal
production conditions. A field management system must be
devised for these cultivars to optimize agronomic traits
and chemical constituents of the cured leaf. Field
experiments were conducted at the Southern Piedmont
Agricultural Experiment Station near Blackstone, Virginia
in 1987 and 1988 to determine the influence of nitrogen
rate, harvest frequency, and time and number of basal leaf
removal on several agronomic and chemical properties of a
mammoth cultivar of flue-cured tobacco. The feasibility of
chemically topping two mammoth cultivars was also
investigated. Increasing nitrogen rates increased values
per hectere by $176 and total alkaloids by 0.5% in 1987.
Increasing the number of harvest increased percentage lugs (X) and reducing sugars for stalk position B in 1988 but
decreased reducing sugars for stalk positions A and C in
1988. Delaying leaf removal increased yield and values per
hectare by 141 kg ha-1 and $84, respectively, and
decreased lug production in 1987 and 1988. Total alkaloids
decreased by 0.7% with delayed leaf removal in 1987.
Delayed leaf removal increased reducing sugars at stalk
position A by 2% in 1988. Removing fewer basal leaves
increased yields by 115 kg ha-1, values per hectare, and
percentage smoking leaf (H) for both years. Alkaloids for
stalk position B increased with fewer basal leaves removed
in 1988. Decreased basal leaf removal decreased plant
height by 9 cm, percentage leaf (B), and reducing sugars in
stalk positions A, B, and D in 1988. Delaying basal leaf
removal and decreasing harvest frequency increased the
percentage of cutters (C). Percentage smoking leaf
increased with nitrogen rate and removal of fewer basal
leaves. Chemical topping created taller plants with more
leaves, narrower tip leaves, lower total alkaloids, and
equal or higher reducing sugars relative to hand topping.
Tip leaves from chemically topped plants were 6 to 8 cm
shorter than hand-topped plants in 1987. Maleic hydrazide
treatments resulted in 429 to 700 kg ha-1 lower yields and
lower values than hand topping and 6 more suckers than all
other treatments. The fatty alcohol / maleic hydrazide
treatment produced 380 kg ha-1 higher yields and grade
indices lower than the hand-topped control in 1987. Above
normal nitrogen rate, 3 or 5 time harvest, removal of 4 to
6 leaves at topping or via senescence, and chemical topping
with Prime+ or fatty alcohol / maleic hydrazide tank mix
provided the best field management system for mammoth
cultivars under the conditions of this study.
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