Test Procedures
In 28 experiments, 46 new CP clones (11 clones of the CP 93
series in the plant crop, 11 clones of the CP 92 series in the
plant-cane and first-ratoon crops, 12 clones of the CP 91 series
in the first- and second-ratoon crops, and 12 clones of the CP
90 series in the second-ratoon crop) were evaluated at 9 farms.
CP 91-2246 and CP 91-1560 were included in 9 of the 10 experiments
with CP 91 series clones, and CP 91-1609 was tested at one location
with CP 91 series clones. In the second-ratoon experiments of
the CP 90 series clones, CP 90-1428 was planted at the two farms
with organic soils and CP 90-1030 at the farm with a sand soil.
CP 70-1133 was the reference clone in all 28 experiments. It
was the second most widely grown cultivar on sand soils but only
a minor cultivar on organic soils in Florida. Overall, CP 70-1133
was the sixth most widely grown sugarcane cultivar in Florida
(Glaz 1997).
The second-ratoon experiment at A. Duda and Sons (Duda) southeast
of Belle Glade, the CP 92 series first-ratoon and the two second-
ratoon experiments at Okeelanta Corporation (Okeelanta) south
of South Bay, and the first-ratoon experiment at Knight Management
(Knight) southwest of 20-Mile Bend were conducted on Dania muck
soils. As described by McCollum et al. (1976),
Dania is the shallowest of the organic soils in the Everglades
agricultural area that is composed primarily of decomposed sawgrass
(Cladium jamaicense Crantz). The other organic soils similar
to Dania muck, listed in order of increasing depth, are Lauderhill,
Pahokee, and Terra Ceia mucks.
Ten experiments were conducted on Lauderhill mucks--all three
experiments planted at Sugar Farms Co-op Western Division (SFCW)
east of Canal Point, all three experiments planted at Wedgworth
Farms (Wedgworth) east of Belle Glade, the plant-cane and second-ratoon
experiments at Knight, the first-ratoon experiment at Duda, and
the CP 93 series plant-cane experiment at Okeelanta.
The two ratoon experiments at Sugar Farms Co-op Eastern Division
(SFCE) near 20-Mile Bend in Palm Beach County, the plant-cane
experiment at Duda, the CP 92 series plant-cane experiment at
Okeelanta, and the CP 91 series first-ratoon experiment at Okeelanta
were conducted on Pahokee muck soils.
The three experiments at Eastgate Farms (Eastgate) north of
Belle Glade were on Torry muck. The three experiments at Hilliard
Brothers' of Florida (Hilliard) west of Clewiston were on Malabar
sand. The two experiments at Lykes Brothers' Farm (Lykes) near
Moore Haven in Glades County were on Pompano fine sand.
The two experiments at Lykes and the CP 92 series plant-cane,
the CP 91 series first-ratoon, and the CP 90 series second-ratoon
experiments at Okeelanta were planted on fields in successive
sugarcane rotations. The other experiments were planted in fields
that had not been cropped to sugarcane for approximately 1 year.
In all experiments, clones were planted with two lines of seed
cane per furrow in plots arranged in randomized complete-block
designs with eight replications. Each two-row plot was 10.7 m
long and 3 m wide (0.0032 ha). The distance between rows was 1.5
m, and 1.5-m alleys separated the front and back ends of the plots.
The margins of the experiments were protected with an extra row
of sugarcane on each side (usually the same clone as planted in
the adjacent plot) and an extra 1.5 m of sugarcane in the front
and back.
Samples of 10 stalks per plot were cut from unburned cane from
all plots in each experiment between October 6, 1997, and February
25, 1998. In all experiments, one sample was cut from the middle
row of each plot. In addition, a preharvest sample was cut from
two replications of seven plant-cane experiments between October
10, 1997, and October 30, 1997. For all samples, once a stool
of sugarcane was chosen for cutting, the next 10 mature stalks
in the row were cut as the 10-stalk sample. The range of sampling
dates for each crop was as follows: October 28, 1997, to February
25, 1998, for the plant crop; November 25, 1997, to February 25,
1998, for the first-ratoon crop; and October 6, 1997, to December
19, 1997, for the second-ratoon crop. After the stalk samples
were transported to the Agricultural Research Service's Sugarcane
Field Station at Canal Point for weighing and milling, crusher
juice samples from the stalks were analyzed for Brix and sucrose,
and theoretical recoverable yields of kg 96° sugar per metric
ton of cane (KS/T) were determined as a measure of sugar production.
The procedure used to calculate these yields using fiber percentages
is described by Legendre (1992).
Total millable stalks per plot were counted between June 25
and September 15, 1997. Yields of metric tons of cane per hectare
(TC/H) were calculated by multiplying stalk weights by number
of stalks. Theoretical yields of metric tons of sugar per hectare
(TS/H) were calculated by multiplying TC/H by KS/T and dividing
by 1,000.
Analyses of variance were done using the procedures described
by McIntosh (1983). F-ratios
were chosen according to a mixed model, with treatments (clones)
fixed and locations random. The source of variation that corresponded
to the error term for the effect being tested was used to calculate
the least significant difference (LSD). LSD was
used regardless of significance of F- ratios in all analyses
to protect against high type-II error rates, and significant differences
were sought at the 10-percent probability level (Glaz
and Dean 1988).
Analyses of clonal stability across locations were done by
using the procedures recommended in Shukla (1972).
For each clone, the stability-variance parameter of Shukla was
subsequently used to calculate (at the 1-percent probability level)
a stability-safety index as described by Eskridge (1990).
The mean yield of the clone and the stability of the clone across
locations influence the value of this stability-safety index.
The higher the stability-safety index, the more likely the clone
is to have high yields at all locations.
Before the clones were evaluated in stage IV, they were tested
in separate tests by artificial inoculation for susceptibility
to sugarcane smut, sugarcane mosaic virus, leaf scald, and RSD.
Clones were inoculated in stage II plots to determine eye spot
susceptibility. Since being advanced to stage IV, separate artificial-inoculation
tests were repeated with pathogens of smut, RSD, mosaic, and leaf
scald. Each clone was also rated for its reactions to natural
infection by sugarcane smut, sugarcane rust, sugarcane mosaic
virus, and leaf scald. The farm management at each location controlled
sugarcane management practices, such as fertilization, cultivation,
and pest control.
Two separate tests were conducted at Gainesville, Florida,
to determine cold tolerance of clones from the CP 92 and CP 93
series. These tests were conducted at the Florida Institute of
Food and Agricultural Sciences' Greenacre Agronomy Farm. The experiments
were planted in randomized complete blocks with six replications.
Plots were 1.5 m long and 2.1 m wide. A moderate freeze of -2
°C occurred on December 6, 1997, followed by a second freeze
of -4 °C on December 7. Stalks were sampled for the analysis
of sucrose content on December 18, 1997, and February 2, 1998.
The cold-tolerance rating was based on the deterioration of juice
quality after the freeze damage to mature sugarcane stalks.
United States
Department of Agriculture
Agricultural
Research Service
The material on this page is in the public
domain.
Original posting: April 19, 1999.
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