Evaluation of New Canal Point Sugarcane Clones
1998-99 Harvest Season

Test Procedures

In 28 experiments, 44 new CP clones (11 clones of the CP 94 series in the plant-cane crop, 11 clones of the CP 93 series in the plant-cane and first-ratoon crops, 11 clones of the CP 92 series in the first-and second-ratoon crops, and 11 clones of the CP 91 series in the second-ratoon crop) were evaluated at nine farms.

CP 70-1133 was the reference clone in all 28 experiments. It was the third most widely grown cultivar on sand soils but only a minor cultivar on organic soils in Florida. Overall, CP 70-1133 was the eighth most widely grown sugarcane cultivar in Florida (Glaz 1998).

The CP 93 series first-ratoon experiment and the second-ratoon experiment at Okeelanta Corporation (Okeelanta) south of South Bay and the first-ratoon experiment at Knight Management, Inc. (Knight), southwest of 20-Mile Bend were conducted on Dania muck. As described by McCollum et al. (1976), Dania muck is the shallowest of the organic soils in the Everglades Agricultural Area that is composed primarily of decomposed sawgrass (Cladium jamaicense Crantz). The maximum depth to bedrock in a Dania muck is 51 cm. The other organic soils similar to Dania muck are Lauderhill (51-91 cm deep to bedrock), Pahokee (91-130 cm deep), and Terra Ceia mucks (more than 130 cm deep).

Six experiments were conducted on Lauderhill muck--the second-ratoon experiments at A. Duda and Sons, Inc. (Duda), southeast of Belle Glade and Sugar Farms Co-Op Western Division (SFCW) east of Canal Point; both plant-cane and the first-ratoon CP 93 series experiments at Okeelanta; and the plant-cane experiment at Wedgworth Farms, Inc. (Wedgworth), east of Belle Glade.

Nine experiments were conducted on Pahokee muck--all three experiments at Sugar Farms Co-Op Eastern Division (SFCE) near 20-Mile Bend in Palm Beach County, the plant-cane and first-ratoon experiments at Duda, the plant-cane and second-ratoon experiments at Knight, and the two ratoon experiments at Wedgworth.

The plant-cane experiment at SFCW was planted on a Terra Ceia muck. The three experiments at Eastgate Farms, Inc. (Eastgate), north of Belle Glade were on Torry muck. The three experiments at Hilliard Brothers of Florida Ltd. (Hilliard) west of Clewiston were on Malabar sand. The three experiments at Lykes Brothers' Farm (Lykes) near Moore Haven in Glades County were on Pompano fine sand.

The CP 93 and CP 92 series experiments at Lykes and the CP 93 series plant-cane and the CP 92 series first-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 three-row plot was 10.7 m long and 3 m wide (0.0032 ha). The distance between rows was l.5 m, and 1.5-m alleys separated the front and back ends of the plots. The outside row of each plot was a border row, and it was usually planted with the same clone as the inside two rows. An extra 1.5 m of sugarcane protected the front and back of each test.

Samples of 10 stalks per plot were cut from unburned cane from all plots in each experiment between October 2, 1998, and March 11, 1999. In all experiments, one sample per plot was cut from the middle row of each plot. In addition, a preharvest sample was cut from two replications of 12 plant-cane experiments between October 15, 1998, and October 28, 1998. For all samples, once a stool of sugarcane was chosen for cutting, the next 10 stalks in the row were cut as the 10-stalk sample. The range of sample dates for each crop was as follows:

Plant-cane crop	November 26, 1998, to March 10, 1999
First-ratoon crop	November 27, 1998, to March 11, 1999
Second-ratoon crop	October 2, 1998, to December 29, 1998

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 pol, and theoretical recoverable yields of 96° sugar in kilograms 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 July 5 and October 9, 1998. 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 procedures described by McIntosh (1983). F-ratios were chosen according to a mixed model, with 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). Least significant difference 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 procedures recommended by Shukla (1972). For each clone, the stability-variance parameter of Shukla was subsequently used to calculate (at the 1-percent probability level) the stability-safety index 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 for 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, CP 93, and CP 94 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 -2.2 °C occurred on December 6, 1998, and another moderate freeze of -3.9 °C occurred on December 7, 1998. A severe freeze of -7.8 °C occurred on January 6, 1999. Stalk samples were cut for analyses of sucrose content on December 14, 1998, January 14, 1999, and February 2, 1999. The cold-tolerance rating was based on deterioration of juice quality after the freeze damage to mature sugarcane stalks. However, the clones had considerable differences in maturity at the times of the freezes and samples. Level of maturity probably affected degree of cold injury and subsequent deterioration of juice quality.

previous page

next page

United States Department of Agriculture
Agricultural Research Service

The material on this page is in the public domain.

Original posting: June 20, 2000.