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Copyright 2005, Board of Trustees, University
Fort Pierce ARC Research Report RL-1974-6 June 1974
GROWTH STUDIES IN SOME NEW STYLOSANTHES HAMATA'" (I.) SELECTIONS
John B. Brolmann- DC
The natural distribution of Stylosanthes hamata (;) L. in southeast
Florida is along the coast in a five to ten mile wide strip~ fpo iT he Florida
Keys to approximately 20 miles south of Fort Pierce (latitudinal range of
about 250N to 270N). Urban development is rapidly destroying the habitat of
the species. Several Stylosanthes spp. are currently used for pasture (1, 3).
Since S. hamata has potential as a pasture plant, seeds and plants were
collected from several locations along the southeast Florida coast in the
spring of 1973.
The objective of the current study was to determine if there were
agronomical and morphological differences between plants from different
Materials and Methods
Seeds of S. hamata were collected near Florida City, West Palm Beach,
Miami Beach, and Riviera Beach. Plants from these collections will be referred
to as FLC, WPB, MB, and RB, respectively. Seeds of these collections and of
the Australian introduction were germinated on moistened filter paper in petri
dishes in the laboratory (at approximately 250C). The seeds were transferred
to a dune soil from Fort Pierce beach in plastic trays (50 x 30 x 6cm) when
cotyledons were visible. The seeds were inoculated with Rhizobium strain
150D1, isolated from Stylosanthes spp. in Australia and obtained from J. C.
Burton, Nitragin Company, Wisconsin. When seedlings reached an average
length of three cm, they were transferred to crocks filled with ten kg screened,
air-dried, virgin Oldsmar fine topsoil. The soil had been thoroughly mixed
with a portable cement mixer. Twenty grams of lime and two grams of an
0-10-20 fertilizer were added per crock at the beginning of the experiment.
Muriate of potash (0.75 gr per crock) was added to all plants after the second
Five plants were grown in each crock. There were four replications of
each treatment. Plants were placed outside and watered when needed with
untreated well water. Data were collected on flowering, dry matter production,
shoot length, leaf size, and crown branch density at 10 cm. Plants were cut
10, 15, and 22 weeks after the seedlings were transferred to crocks, each
time leaving a stubble 10 cm high. Samples of the first harvest were analyzed
1/ Assistant Professor, University of Florida, Institute of Food and Agri-
cultural Sciences, Agricultural Research Center, Fort Pierce.
for percentage in vitro organic matter digestibility (IVOMD) by the method of
Moore et al (2). The samples were oven dried at 70 C and ground in a Wiley-
mill to pass a 20 mesh screen before analysis.
Results and Discussion
Dry matter production, morphological characters, and percentage in vitro
digestibility for the selections are presented in Table 1. There were signi-
ficant differences in stem-branching density, shoot length, length of center
leaflet, and in vitro digestibility between the selections. No such differences
were observed within a given selection. The RB selection had the greatest
number of lateral branches, twice as many as the C.P.I. 38842 introduction. The
smallest leaves were found in the WPB selection followed by th- FLC and MB
selections. C.P.I. 38842 had the largest leaves. There were significant
differences in % in vitro digestibility. Lowest values were shown in the RB
selection and highest in the C.P.I. 38842 introduction.
The RB selection produced the greatest amount of dry matter at all three
harvest dates. At the third harvest the RB selection yielded almost three
times as much as C.P.I.' 38842. Field studies in which the progenies of the
same five selections were tested (J. B. Brolmann, unpublished data) also
indicate that the RB selection is the highest yielding type.
All selections except the RB selection began to bloom in the first week
of July. Some flowers were observed on the RB selection at first harvest
(August 15). After cutting, no more flowering occurred on the RB selection
until near the second harvest date, five weeks later. These data indicate
that the RB selection is later maturing and this probably explains its
greater yield in later harvests.
The occurrence of differences in productivity and time of maturity in
local selections of S. hamata native to Florida makes collection and screening
of plants from different areas important so that certain desirable character-
istics can be utilized in a breeding program.
Four selections of Stylosanthes hamata (1.) Taub. collected from the
southeast coast of Florida at four different locations and one Australian
introduction (C.P.I. 38842) were inoculated with a specific Rhizobium strain
and grown in crocks containing virgin Oldsmar fine sand soil. The best
growth was shown by plants collected from near Riviera Beach. Although
there were few morphological differences within individual collections, there
were significant differences between plants collected from different areas.
1. Burt, R. L., Edye, L. A., Grof, B., and Williams, R. J. (1970) -
Assessing the agronomic potential of the genus Stylosanthes in
Australia. Proceedings of the XI International Grassland Congress,
Surfers Paradise, Australia, 1970. 219-23.
2 Moore, J. E., Mott, G. 0., Durham, D. G., and Omer, R. W. (1972) Large
capacity in vitro organic matter digestion procedure. Journal of
Animal Science 35: P. 232 (Abstract).
3. Tuley, P. (1968) Stylosanthes gracilis. Herbage Abstracts 38:87-94.
Table 1. Dry matter production, in vitro digestibility, and morphological traits in five
Stylosanthes hamata selections.
Selections O1 wks. 15 wks.. 2 1wks. Total
-- - g7pot - -- - -
In vitro Stem-branching
digestibility density at 10 cn
Av. length center
S shoot 1cleflk&t'
* Values in vertical columns which are followed by a letter
the 5% level of probability.
in common, are not significantly different at