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Registration of ‘HoCP 00-950’ Sugarcane T. L. Tew,* E. O. Dufrene, D. D. Garrison, W. H. White, M. P. Grisham, Y.-B. Pan, E. P. Richard, Jr., B. L. Legendre, and J. D. Miller ABSTRACT ‘HoCP 00-950’ (Reg. No. CV-135, PI 654823) sugarcane (a complex hybrid of Saccharum officinarum L., S. spontaneum L., S. barberi Jeswiet, and S. sinense Roxb. amend. Jeswiet) was selected and evaluated by the USDA-ARS, working cooperatively with the Louisiana State University AgCenter, and the American Sugar Cane League, Inc. It was released to growers in Louisiana in April 2007. In 67 machine-harvested trials on light- and heavy-textured soils from 2004 to 2007 (plant-cane through third-ratoon crop) averaged over nine southern Louisiana locations, HoCP 00-950 produced 5% more sugar and had 6% higher sugar content than the industry standard, ‘HoCP 96-540’. In plant-cane and ratooncrop maturity tests harvested in 2007, HoCP 00-950 had significantly higher sugar content than HoCP 96-540 across all harvest dates, with 35% higher sugar content at the outset of the harvest season (late September). HoCP 00-950 is resistant to brown rust (Puccinia melanocephala), smut (Ustilago scitaminea), leaf scald (Xanthomonas albilineans), and mosaic diseases. It is susceptible to the sugarcane borer (Diatraea saccharalis) and should not be planted in areas where pesticide use is restricted. The early maturity characteristic of HoCP 00-950 provides growers with a variety that can produce profitable sugar yields early in the milling season without the need to apply a chemical ripener.
B
ased on its pedigree, HoCP 00-950 (Reg. No. CV-135, PI 654823) sugarcane (Saccharum spp.), is a complex hybrid whose genomic makeup consists largely of genes contributed by S. officinarum L. and S. spontaneum L., with minor input from S. barberi Jeswiet and S. sinense Roxb. amend. Jeswiet. Modern sugarcane cultivars such as HoCP 00-950 are allopolyploid (or aneuploid) hybrid derivatives of a few progeny populations developed by crossing S. officinarum × S. spontaneum and backcrossing to the officinarum background to recover the high sucrose content (Roach, 1972; Sreenivasan et al., 1987).
T.L. Tew, E.O. Dufrene, D.D. Garrison (retired), W.H. White, M.P. Grisham, Y-B. Pan, E.P. Richard, Jr., and B.L. Legendre, USDA-ARS, SRRC, Sugarcane Research Unit, 5883 USDA Rd., Houma, LA 70360; B.L. Legendre, current address: Louisiana State Univ. Agric. Center, Sugar Research Station, 5755 LSU Ag Rd., St. Gabriel, LA 70776; J.D. Miller, USDA-ARS, Sugarcane Field Station, 12990 US Hwy. 441 N, Canal Point, FL 33438 (retired). Registration by CSSA. Received 23 July 2008. *Corresponding author (
[email protected]). Abbreviations: CVB, colonized vascular bundles; LSU, Louisiana State University; SCMV, Sugarcane mosaic virus, SRL, Sugarcane Research Laboratory; SrMV, Sorghum mosaic virus; RSD, ratoon stunting disease; SSR, simple sequence repeat. Published in the Journal of Plant Registrations 3:42–50 (2009). doi: 10.3198/jpr2008.07.0430crc © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
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The earliest known maternal ancestor of HoCP 00-950 was ‘Bandjermasin Hitam,’ a S. officinarum accession used by sugarcane breeders on the island of Java (Indonesia) in the early 1900s. Of the 20 commercial sugarcane cultivars released in Louisiana since 1975, only HoCP 00-950 and ‘Ho 95-988’ (Tew et al., 2005a) were maternally derived from Banjermasin Hitam; the other 18 were maternally derived from ‘Black Cheribon’ (S. officinarum). At the time HoCP 00-950 was released, nearly 90% of the area planted to sugarcane in Louisiana was either planted to ‘LCP 85-384’ (Milligan et al., 1994) or one of its progeny, namely, ‘HoCP 96-540’ (Tew et al., 2005b) or ‘L 97-128’ (Gravois et al., 2008). There is a need for increased genetic diversity in Louisiana’s sugar industry, and the release of HoCP 00-950 helps address this need.
Methods Crossing and Early Selection Stages HoCP 00-950 was selected by scientists from the USDA-ARS Sugarcane Research Laboratory (SRL) at Houma, LA from a cross between HoCP 93-750 and HoCP 92-676. The parents are full-sib progeny of CP 84-722 × LCP 81-30. The cross was made at the USDA-ARS Sugarcane Field Station at Canal Point, FL, in December 1995. The breeding facilities at Canal Point are used to support sugarcane cultivar development programs in Florida (CP), Louisiana (HoCP), and Texas (TCP). A summary of the steps leading to the release of HoCP 00-950 as a commercial cultivar is displayed in Table 1. Seed from the cross, HoCP 93-750 × HoCP 92-676, was planted in the SRL greenhouse at Houma, LA, early in January 1996, and seedlings were transplanted to the field at the USDA Research Farm at Schriever, LA, in April 1996 using
Journal of Plant Registrations, Vol. 3, No. , January 2009
Table 1. Summary of the stages of development, evaluation, and eventual release of commercial sugarcane cultivar HoCP 00-950.
September 1998. Selection criteria are similar to those in seedling stage. Year Stage To begin Stage 3, locally referred to as second-line 1995 Cross made in December 1995 at the USDA Sugarcane trial stage, six stalks were cut at the base, topped to Field Station, Canal Point, FL produce a final stalk length of approximately 2 m, 1996 Seed germinated at the USDA greenhouses at Houma, LA, and planted in single-row plots 4.0 m in length with and seedlings planted into the field at the USDA Research Farm at a 0.9-m border between plots along the row. SelecSchriever, LA tion in Stage 3 is a 2-yr process. Harvestable stalks 1997 Selection in first-ratoon seedling crop (advanced to first-line trial) (>1.4 m length) were counted and recorded on all 1998 Selection in plant-cane first line trials (advanced to second-line trial) clones in the first year (plant-cane crop), and only 1999 Selection in plant-cane second line trials (advanced to increase plot) on the more elite clones in the second year (first2000 Assignment in first-ratoon second-line trial On-station yield trials planted (St. Gabriel, Schriever, Jeanerette; 2-rep) ratoon crop). Clones preselected as the more elite in the first year were sampled and included in increase 2001 Plant-cane on-station yield trials harvested (3 locations; 2 rep) Off-station yield trials planted (Bunkie, Paincourtville; 2 rep) plots (seedcane source) in the event that they were Infield yield trials planted (Vacherie, Youngsville; 2 rep) selected for advancement the following year. Prese2002 First-ratoon on-station yield trials harvested (3 loc; 2 rep) lection in the first year was based on stalk count, and Plant-cane off-station yield trials harvested (2 loc; 2 rep) an overall 1 to 9 visual assessment of yield, harvestPlant-cane infield yield trials harvested (2 loc; 2 rep) ability, and evidence of susceptibility to diseases and 2003 Second-ratoon on-station yield trials harvested (3 loc; 2 rep) insects, where 1 = most desirable and 9 = least desirFirst-ratoon off-station yield trials harvested (2 loc; 2 rep) able. Preselected clones were sampled again in the First-ratoon infield yield trials harvested (2 loc; 2 rep) Outfield trials planted at nine locations across sugarcane second year. growing area (3 rep) Sampling was done by hand-cutting 10 stalks 2004 Second-ratoon off-station yield trials harvested (2 loc; 2 rep) at ground level and just below the apical meristem, Second-ratoon infield yield trials harvested (1 loc; 2 rep) Plant-cane outfield trials harvested (9 loc; 2 rep) removing leaf and sheath tissue and then weighing the 10-stalk sample to obtain an estimate of indi2005 Third-ratoon off-station yield trials harvested (1 loc; 2 rep) Third-ratoon infield yield trials harvested (1 loc; 2 rep) vidual stalk weight. The sample was then shredded, First-ratoon outfield trials harvested (9 loc; 2 rep) and juice was expressed from a 1-kg sample in a core 2006 Second-ratoon outfield trials harvested (7 loc; 2 rep) press at 211 kg cm–1 pressure. The remaining “cake” 2007 Cultivar release of fibrous residue was weighed then dried at 66°C for Third-ratoon outfield trials harvested (2 loc; 2 rep) 72 h to obtain fiber content. Brix and pol were measured hydrometrically and by polarimetry, respectively in a juice quality laboratory to determine total a spacing interval of 40 cm along 1.8-m-wide raised beds soluble solids and sucrose content in each sample; from to establish Stage 1 (seedling stage). At Stage 1, the seedthese, together with fiber content, theoretically recoverable lings are cut back in the late fall, and those that survive the sucrose content (kg Mg–1) was estimated as described by Legendre (1992). Cane yield (Mg ha–1) was estimated as the winter undergo selection in fall of the following year. In product of stalk population per hectare × individual stalk the case of HoCP 00-950, initial selection occurred in 1997. weight. Sugar yield (Mg ha–1) was estimated as the product Selection criteria in the early clonal stages included yield of cane yield × sugar content/1000. components (stalk number, diameter, and height), quality Following selection, the permanent cultivar name, HoCP components (Brix only in Stages 1 and 2; sucrose and fiber 00-950, was assigned in the first-ratoon crop of Stage 3 in in Stage 3), resistance or tolerance to natural disease and 2000. Both plant-cane and ratoon-crop data were considinsect pressures, and general freedom from traits that could ered before final selection and permanent cultivar name adversely affect harvestability, such as proneness to lodge assignment. and stalk brittleness. A hand punch and hand refractometer were used to measure Brix in the first two stages. Two Replicated Yield Trials stalks were punched, each at approximately 1/3 the disReplicated on-station nursery trials were conducted at the tance from ground level to the uppermost visible dewlap of USDA Research Farm in Schriever, LA, the Louisiana State the stalk. About 1 mL of juice was extracted from each stalk, University (LSU) AgCenter’s Sugar Research Station in St. collected in a small reservoir located on the hand punch Gabriel, LA, and the LSU AgCenter’s Iberia Research Staand then transferred to the hand refractometer. At all early tion in Jeanerette, LA. At each location, a randomized comstages of evaluation, commercially important cultivars in plete block design with two replications was used. Plots the industry were included as standards. For HoCP 00-950, consisted of single 1.8-m-wide rows that were 4.0 m long these standards were ‘CP 70-321’ (Fanguy et al., 1979), LCP with a 0.9-m gap between plots along each row. Data were 85-384, ‘HoCP 85-845’ (Legendre et al., 1994) and ‘LHo collected in the plant-cane, first-ratoon, and second-ratoon 83-153’ (Bischoff et al., 1992). crops. Data obtained from these trials included stalk popuTo begin Stage 2, locally referred to as first-line trial stage, lation (stalks ha–1), stalk weight (kg), sugar content (Mg ha–1), selected progeny were advanced by cutting two stalks at cane yield (Mg ha–1), and sugar yield (Mg ha–1). The number 1.2 m length and planting them 1.8 m apart in single-row of harvestable stalks in each plot was determined in early plots. Selection in Stage 2 occurred the following year in Journal of Plant Registrations, Vol. 3, No. 1, January 2009
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August. As in the second clonal stage, yield estimates were based on 10-stalk hand-cut samples, and the samples were processed using the prebreaker/press method. The following year, replicated off-station nursery trials were conducted on grower fields at Newton Cane, Inc. in Bunkie, Louisiana; and Westfield Plantation in Paincourtville, Louisiana. Trials were harvested in the plant-cane, first-ratoon, and second-ratoon crops. The plots for these trials were single 1.8-m wide rows that were 6.1 m long with a 1.5-m alley between plots along the rows. Stalk weight, sugar content, and cane and sugar yields were estimated based on stalk counts and 10-stalk hand-cut samples as described earlier. Initial yield trials, locally referred to as infield tests, were planted in the same year that off-station nursery trials were planted. They were conducted at Sugarland Acres, Inc. in Youngsville, LA, and Blackberry Farms in Vacherie, LA. At this stage and beyond, selected clones are tested along with those from LSU AgCenter’s breeding program and evaluated by scientists from USDA-ARS, LSU AgCenter, and the American Sugarcane League. The plots for infield tests were two adjacent 1.8-m-wide rows that were 7.6 m long with a 1.5-m alley between plots. The experimental design for each of these trials was a randomized complete block design with two replications. Cane from each plot was mechanically harvested using combine harvesters and a weigh wagon equipped with electronic load cells to record cane weight. Harvested cane weights from each plot were used to calculate cane yield. Stalk weight, sugar content, and cane and sugar yields were estimated based on a 10-stalk hand-cut sample. The fi nal yield testing stage of the SRL’s sugarcane breeding program, locally referred to as outfield tests, were conducted cooperatively as described above. Fortyfive mechanically harvested outfield tests were conducted across nine south Louisiana locations during the 2004 to 2007 (representing plant-cane, fi rst-, second-, and thirdratoon crops) harvest seasons. The outfield test sites are widely dispersed throughout the Louisiana sugarcane industry and are in both light and heavy soil locations (7 silt loam locations; 2 clay locations). The experimental design for each of these tests was a randomized complete block with three replications. Fifteen-stalk samples were collected before harvest to determine stalk weight and for a juice quality analysis. For juice quality analysis, samples were crushed using a small three-roller mill rather than shredded as before. Fiber content is a highly repeatable trait, so to increase throughput and conserve on resources, the roller mill method is used at this stage. Plots were mechanically harvested as in the infield trials. No burning was done before harvest regardless of the stage of advancement.
Disease and Insect Evaluations The reaction of HoCP 00-950 to the important endemic diseases of sugarcane in Louisiana was determined from observations in performance trials and from artificial inoculated greenhouse and field trials.
44
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Mosaic In Year 8, young plants of candidate cultivars including HoCP 00-950 were artificially inoculated in the greenhouse as described by Grisham (1994) with Sorghum mosaic virus (SrMV) and Sugarcane mosaic virus (SCMV), the two viruses reported to cause mosaic in the continental United States.
Smut Beginning in year six of the cultivar evaluation program and continuing until release, HoCP 00-950 was included in inoculated field trials at the USDA Research Farm in Schriever, LA, and the LSU AgCenter’s Sugar Research Station in St. Gabriel, LA to test for smut (caused by Ustilago scitaminea H. and P. Sydow) susceptibility. Eighteen stalks (six stalks per replicate) of each cultivar were dipped in a suspension of approximately 5 × 106 smut teliospores mL –1 with >90% germination for 10 min and then planted immediately. The experimental design for each of these trials was a randomized complete block design with three replications and individual plots consisting of a single row 4.9 m long. Disease ratings were made in mid-June to mid-July during the subsequent plant-cane growing season. Clones were ranked according to the percentage of stalks with whips and assigned a rating of 1 to 9, where 1 = no whip formation and 9 = the group of clones with the highest percentage of stalks with whips, generally >30%. Because the range of percentage stalks with whips that define each rating varies from trial to trial as a result of the environmental effects, 10 commercial cultivars that range from resistant (rating < 3) to susceptible (rating > 7) were included as standards for comparison.
Leaf Scald The two smut field trials were also used for testing experimental clones for resistance to leaf scald [caused by Xanthomonas albilineans (Ashby) Dowson]. At the USDA research farm, plants were inoculated in April, approximately 1 mo after growth was initiated following winter dormancy when the apical growing point was still below the soil surface. The leaf whorl of all plants in the trial was mowed to a height of about 5 cm and immediately sprayed with a suspension of bacterial cells of X. albilineans (Ashby) Dowson. Bacterial cells were recovered from 7- to 10-d-old cultures grown on Wilbrink agar plates and suspended in distilled water. Bacterial densities were adjusted to approximately 1 × 106 colony-forming units mL –1 using a spectrophotometer. Plants in the test plots at St. Gabriel were inoculated when they were approximately 3 mo old by hand clipping the leaf whorl of each shoot and spraying the cut surface immediately with a suspension of X. albilineans cells at a similar concentration. Clones of both trials were visually inspected for leaf scald susceptibility in August and October and the percentage of stalks showing acute (systemic) infection was determined for each clone. An average severity rating of 1 to 9 was assigned to each plot, where 1 = no symptoms, 3 = single “white pencil line” symptoms, 5 = multiple white pencil lines per leaf that become necrotic, 7 = significant disease development with younger leaves Journal of Plant Registrations, Vol. 3, No. 1, January 2009
and replication and their interactions as random variables. Freeze tolerance was also analyzed using PROC MIXED. Least square means were generated for each cultivar and were separated using the PDIFF option (P ≤ 0.05). Ratoon stunting disease data were analyzed using SAS with PROC MIXED with replication as a random variable. Differences between treatment least square means were compared using the PDIFF option at the 0.05 probability level. Entomolological and maturity data were analyzed using PROC GLM (SAS Institute, 2003) and cultivar means were separated using Fisher’s Protected LSD (P ≤ 0.05).
showing necrotic lines, and 9 = leaf whorl dying and lateral buds germinating. Ratings were based on a comparison with inoculated cultivars with known levels of resistance and susceptibility to leaf scald.
Brown Rust Performance trials were observed during the spring and summer periods when the conditions for brown rust development from natural infection by Puccinia melanocephala H. and P. Sydow were favorable.
Ratoon Stunting Disease The effect of ratoon stunting disease (RSD; caused by Leifsonia xyli subsp. xyli Evtsuhenko et al.) on HoCP 00-950 was determined in field experiments as described by Grisham (1991). Infection levels based on the number of colonized vascular bundles (CVB) and effects on yield were determined each fall for two crop cycles (2004–2006 and 2005–2007), each consisting of plant-cane, first-ratoon, and second-ratoon crops.
Sugarcane Borer HoCP 00-950 was evaluated for its response to the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae). The sugarcane borer is an important pest of sugarcane throughout the Americas and the most important insect pest of sugarcane in the U.S. Procedures for evaluating cultivars for sugarcane borer resistance are those reported by White et al. (2008). Evaluations were conducted in 2004, 2006, and 2007.
Replicated Yield Trials HoCP 00-950 was evaluated in outfield tests that were conducted from 2004 through 2007 (Table 2). Experimental clones were replanted each year in these tests as long as the experimental clone remained active within the sugarcane breeding program. In 2004, the standard cultivar
Table 2. Comparison of sugarcane cultivar HoCP 00950 with commercially important cultivars in outfield trials for 67 combine-harvested trials on light- and heavy-textured soils from 2004 to 2007 averaged over nine southern Louisiana locations. Sugar yield
Cultivar
Cane yield
—— Mg ha –1 ——
Sucrose content kg Mg –1
Stalk Stalk no. weight kg
Stalks ha –1
Plant-cane crop: 2004–2007 (32 harvests) HoCP 00-950
148
0.97
77,789 75,490
61.5−
136−
0.83−
10.84
78.4+
139−
1.07+
74,873
Plant-cane and first-ratoon maturity tests were conducted at the USDA Research Farm to assess the maturity profile of released cultivars and near-release clones. In maturity tests, 15-stalk samples (5 per row) were taken monthly from plant-cane tests and biweekly from first-ratoon tests to track the late-season growth as well as accumulation of sucrose. Clones were planted in a randomized complete block design with three replications. Individual plots consisted of three adjacent 1.8-m-wide rows 13.7 m in length with a 1.2-m alley between plots. Freeze-tolerance trials involving commercial and nearcommercial cultivars are established annually at the USDA Research Farm at Schriever. Two cultivars, LCP 85-384, representing good stalk freeze tolerance, and TucCP 77-42 (Mariotti et al., 1991), representing poor stalk freeze tolerance, are included as controls. Following a damaging freeze, changes in juice pol (sucrose), pH, titratable acidity, and deterioration-related products (Legendre et al., 1985) are monitored, usually on a biweekly basis. The cultivars were planted in a randomized complete block design with three replications. Individual plots consisted of four adjacent, 1.8-m-wide rows 13.7-m in length with a 1.5-m alley between plots.
L 97-128
10.06−
73.3
138−
1.08+
68,304−
L 99-226
11.44
78.4+
146
1.25+
64,051−
10.45−
78.1
134−
0.85−
93,426+
Statistical Analyses Yield data were analyzed using PROC MIXED (SAS Institute, 2003) with cultivar as the fi xed variable and year, location, Journal of Plant Registrations, Vol. 3, No. 1, January 2009
8.35−
74.8
HoCP 96-540
Maturity and Freeze Tolerance Tests
LCP 85-384
11.08 †
L 99-233
First-ratoon crop: 2005–2007 (22 harvests) HoCP 00-950
9.99
66.2
151
0.88
76,930
LCP 85-384
8.47−
61.3−
138−
0.76−
83,054+
HoCP 96-540
9.86
69.8
141−
0.95+
74,948
L 97-128
9.34−
67.2
138−
0.99+
68,781−
L 99-226
10.99+
73.3+
150
1.15+
65,210-
L 99-233
9.61
70.0+
137−
0.78−
92,536+
Second-ratoon crop: 2006–2007 (11 harvests) HoCP 00-950
71.5
145
0.88
83,199
LCP 85-384
10.38 7.60−
59.6−
128−
0.73−
85,700
HoCP 96-540
8.66−
67.5
127−
0.88
78,053
L 97-128
8.91−
65.8
135−
0.92
72,259−
L 99-226
9.66
68.1
142
1.03+
69,193−
L 99-233
9.25−
72.0
128−
0.76-
96,022+
Third-ratoon crop: 2007 (2 harvests) HoCP 00-950
67.8
148
0.76
88,826
LCP 85-384
6.99−
57.6
121−
0.70
82,315
HoCP 96-540
8.71
69.1
126−
0.78
89,814
L 97-128
8.45
62.2
136
0.83
74,827
L 99-226
8.96
65.3
137
0.92+
L 99-233
8.82
72.1
122−
0.72
†
10.04
72,802 101,482
Statistically significant (P = 0.05) differences from HoCP 00-950 are denoted with a plus (+) or minus (-) sign. C U LT I VA R
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for comparison in the Outfield Tests, LCP 85-384, was superseded by HoCP 96-540 to reflect the industry’s shift away from LCP 85-384 toward HoCP 96-540 largely as a result of LCP 85-384’s susceptibility to brown rust disease and decline in yield (Tew et al., 2005b). In the plant-cane, first-, second-, and third-ratoon crops, HoCP 00-950 produced significantly higher sugar yields than LCP 85-384 and sugar yields similar to those of HoCP 96-540. In plantcane through second-ratoon, the sucrose content of HoCP 00-950 was significantly higher than all cultivars except for ‘L 99-226.’ Yields in the later ratoon crops indicate that HoCP 00-950 is an excellent ratooning cultivar. HoCP 00-950 had a fiber content of 11.0% based on all 12 test plots in which it was evaluated, compared with 11.9% average fiber content of HoCP 96-540 in the same test plots.
Disease and Insect Reactions
Table 3. Disease reactions of sugarcane cultivar HoCP 00950 and other cultivars. Cultivar
Smut‡
Brown rust§
Leaf scald¶
Ratoon stunting disease#
LCP 85-384
R
1 (R)
S
1R
S
HoCP 96-540
R
1 (R)
MS
2R
MS
Ho 95-988
R
4 (MS)
S
5R
MR
L 97-128
R
4 (MS)
MS
1R
S
L 99-226
R
3 (MR)
MR
5 MR
S
L 99-233
R
3 (MR)
MR
5 MR
S
HoCP 00-950
R
1 (R)
MR
5R
S
†
R, resistant; S, susceptible.
‡
Ratings were assigned based on percentage of shoots with whips, where 1 = no whip formation and 9 = the group of cultivars with the highest percentage of stalks with whips, typically >30%. R, resistant; MR, moderately resistant; MS, moderately susceptible; S, susceptible.
§
Ratings based on an average visual rating of 0 to 9, where 0–1 = resistant; 2–3 = moderately resistant; 4–6 = moderately susceptible; and 7–9 = susceptible.
¶
Diseases—Natural Infection
Mosaic †
Ratings based on a visual rating of 1 to 9 as described in the “Disease and Insect Reactions” section.
Disease reactions of HoCP 00-950 are shown in Table 3. No visual symptoms of mosaic (SCMV and SrMV), brown rust, smut, or leaf scald were observed among plants of HoCP 00-950 in nurseries or performance trials during evaluation in the varietal development program. Susceptibility of HoCP 00-950 to infection by Sugarcane yellow leaf virus (SCYLV) is unknown. Orange rust [caused by Puccinia kuehnii (W. Krüger) E.J. Butler] first confirmed to be in Florida on 17 July 2007, has not yet been observed in Louisiana. Based on natural infection observations in the crossing area at Canal Point, FL, HoCP 00-950 is moderately resistant to orange rust.
00-950 is susceptible to infection by RSD (Table 4). A high percentage of CVB (77%) was observed in HoCP 00-950 infected with L. xyli susp. xyli. In addition to indicating the potential for yield loss, percentage CVB has also been positively correlated with the extent of L. xyli subsp. xyli spread by mechanical harvesters (Hoy and Grisham, 2006). The average cane and sucrose yield among L. xyli susp. xyli– infected plots of HoCP 00-950 was numerically less (9 and 12%, respectively) than RSD–free plots, although not different at P = 0.05.
Diseases—Artificial Inoculation
Sugarcane Borer
HoCP 00-950 was resistant to mosaic (SCMV and SrMV) under artificial inoculation (Table 3). HoCP 00-950 was resistant to smut but moderately susceptible to leaf scald diseases in inoculated trials. Brown rust pustules with spore production have been observed on HoCP 00-950; however, high levels of infection have not developed on this cultivar compared with susceptible cultivars. Similar to most other commercial cultivars grown in Louisiana, cultivar HoCP
Table 5 summarizes the response of HoCP 00-950 to infestations by the sugarcane borer. HoCP 00-950 is very susceptible to the sugarcane borer, at or near the top for all three evaluation criteria. Extension recommendations should include an advisory for farmers to monitor borer infestations closely and to plant HoCP 00-950 only in areas where the application of insecticides is possible.
#
See Table 4 for infection levels and yield response to ratoon stunting disease.
Table 4. Response of sugarcane cultivar HoCP 00-950 and other cultivars to ratoon stunting disease (RSD) as measured in two crop cycles (plant-cane, first-ratoon, and second-ratoon crops). Cultivar
HWT†
Cane yield RSD
— Mg ha –1 —
Diff.
HWT
%
Sugar yield RSD
Diff.
— Mg ha –1 —
%
CVB‡
Rating§
%
LCP 85-384
76
72
−6.0
7.9
7.5
−4.3
23
HoCP 96-540
90
94
4.5
9.2
9.9
7.8
9
MS
S
Ho 95-988
86
87
1.2
9.3
9.5
2.0
2
MR
L 97-128
74
71
−3.9
7.7
7.7
−0.5
14
S
L 99-226
81
73
−10.7
8.4
7.9
−5.7
69
MR¶
L 99-233
75
56
−26.2*
7.5
5.9
−22.0*
86
S
HoCP 00-950
80
73
−9.2
9.4
8.3
−12.2
77
S
*Differences in mean of variables between control and Leifsonia xyli subsp. xyli-infected plants were significant at P = 0.05. †
HWT, hot-water treated control.
‡
CVB, colonized vascular bundles.
§
R, resistant; MR, moderately resistant; MS, moderately susceptible; S, susceptible.
¶
Cultivar appears to be MR for yield loss but S for infection level.
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Journal of Plant Registrations, Vol. 3, No. 1, January 2009
Table 5. Response of HoCP 00-950 and five other sugarcane cultivars to the sugarcane borer as measured by three evaluation criteria at the USDA Research Farm, Schriever, LA, in 2004, 2006, and 2007. Evaluation criteria
Cultivar Ho 95-988
HoCP 00-950
L 99-233
L 97-128
HoCP 96-540
Bored internodes
31.1A†
30.5A
21.0B
Reduction S/H (%)
14.1A
17.5A
‡
5.4A
Moth production§ †
3.9AB
L 99-226
18.1BC
17.2BC
13.0C
8.4AB
9.2AB
8.8AB
−1.4B
1.9C
2.1BC
2.4BC
Avg. 21.8 9.4
2.8BC
3.1
Means followed by the same letter within a row are not significantly different at p ≤ 0.05.
‡
S/H = sugar per hectare.
§
Moth production values are the number of emergence holes for a cultivar expressed as plot average. Emergence holes are made by larvae before pupation, thereby allowing the moth to exit from the stalk. Emergence holes are visibly larger than entrance holes and are used as a measure of larval success in development.
Maturity Trials Maturity trials are conducted in Louisiana to profile changes in sucrose content from late August through early December. HoCP 00-950 possessed and continued to maintain higher sucrose levels than other cultivars throughout all harvest dates. After 2 yr of evaluation in the plant-cane crop, HoCP 00-950 had a 36% higher sucrose content than LCP 85-384 when harvested in late September (Table 6). After 1 yr of evaluation in the first-ratoon crop, HoCP 00-950 had a 50 and 35% higher sucrose content than LCP 85-384 in late August and late September, respectively (Table 7). Across all dates in the first-ratoon maturity test, HoCP 00-950 had 25% higher sucrose content than LCP 85-384. Outfield test results indicated that HoCP 00-950 and L 99-226 were not significantly different in recoverable sugar content (Table 2). Data from the maturity tests indicate that L 99-226 is later maturing than HoCP 00-950, although both are regarded by the industry as high-sucrose cultivars. Most of the outfield tests were harvested in November and December or toward the later dates shown in the maturity curve.
Freeze Tolerance Trials Freezes capable of causing stalk deterioration occur in Louisiana from December through early February. A freeze occurred on 3 Jan. 2008, allowing us to assess freeze damage that occurred to HoCP 00-950 relative to the controls and other actively grown commercial cultivars. The freeze extended for 12 consecutive hours, reaching a minimum of −4.2°C. As shown in Table 8, which displays the effect of the freeze on recoverable sugar at biweekly intervals up to six weeks following the freeze, HoCP 00-950 appears to have acceptable stalk tolerance to damaging freezes. It did not show a significant decline in sugar content throughout the postfreeze sampling period.
Agronomic, Botanical, and Molecular Descriptions Plant descriptors for sugarcane in USDA-ARS GRIN system were used as a guide (http://www.ars-grin.gov/npgs/descriptors/sugarcane). When planted in the fall, HoCP 00-950 generally emerges relatively quickly (
