Mixed
Mixed Mixed
Mixed Mixed
Mixed Mixed
16.
18.
+1.
18.
19,
+ .
19 20 +1 19 20 +1 ,72 ,24 ,52**,66 .61 .95 .57 .65 .08*
.67 .83 .16*
13.
15.
+1, 15.
16 + 16 18 +1 16 18 +1 ,66
33 ,67**
.43 .42 .99 .93 .07 .14*
.94 .07 .13*
81.
83.
+2, 82.
83, +1, 86 87 +1 86 86 + .77 ,93 ,16 .64 .64 .00*
.51 .52 .01 .09 .74 .65
31.
31.
+, 33, 29.
-4.
36 34 -2 36 36
-
,05 ,41 ,36 ,60 ,07 ,53*
.59 .49 .10 .42 .14 .28
8.
10.
+1.
10.
10.
+ 11 12 + 11 12 + .98 .22 .24**
.23 .97 .74*
.60 .46 .86*
.57 .52 .95**
5,596 6,369 +773*
6,843 6,3 27 - 516 8,475 8,591 +116 8,388 9,033 +645
Both Both
Both Both.
Both Both
Hand Hand
CI 61-5
CI 65-279 CK 2,2.5,3 Change
CK 3 Change
3 3 3 3
—
44_ _
42 1st 1st Pit Pit
19.70 21.10 +1.40 18.87 20.20 +1.33
16.34 18.09 +1.75 16.22 17.39 +1.17
82.79 85.67 +2.88 85.94 86.09 + .15
31.25 30.01 -1.24 32.65 33.84 +1.19
11.02 12.42 +1.40 11.24 12.07 + .83
6,806 7,441 +635 7,342 8,150 +826
Both Both
Hand Hand
*, ** Significantly different at the .05 and .01 levels, respectively, by analysis of variance. Those changes above dashed line not marked by asterick are not significantly different. No statistical analyses of varieties below dashed line.
Table 2. Comparison of Polaris treated and check cane of five varieties which were treated in one or two replications on a commercial scale.
Polaris No. Yield 96° Machine rate repli- Days to Crusher Juice Tons sugar, Lbs. or hand
Variety (lbs/A) cations milling Stubble Brix % Sucrose X Purity cane/A % cane sugar/A harvest CI
CI
CI
CI
CI 41-
49-
54
61
65 223
200
-312
-205
-294 CK
3 Change
CK 3 Change
CK 3 Change
CK 3 Change
CK 3 Change
2 2
—
49__
43__
37__
44__
45 4 th 4 th1st 1st
1st 1st
1st 1st
Pit Pit
19 21 +1 17 17
"
19 20 + 20 21 +1 19 22 +2 66 10 44 70 34 36 62 61 99 18 69 51 81 23 42
17 18 +1 14 14 + 16 17 + 17 19 +1 16 19 +2 24 75 51 14 20 06 85 71 86 05 01 96 55 30 75
87 88 +1 79 81 +2 85 85 + 84 87 +3 83 86 +3 69 86 17 88 89 01 88 93 05 49 64 15 54 82 28
38 34 -3 41 34 -7 40 37 -2 35 31 -4 25 67 58 18 09 09 06 12 94 58 21 37
11 13 +1 9 9 + 11 12 + 11 13 +1 11 13 +2 94 08 14 35 52 17 56 15 59 64 23 59 12 24 12
7,152 6,601 -551 9,521 8,284 -1,237 9,326 9,822 +566 7,913 8,265 +352
Hand Hand Machine Machine Hand Hand Hand Hand Hand Hand
**Significantly different at the .01 level by analysis of variance. Those changes above dashed line not marked by asterick are not significantly different. No statistical analyses of varieties below dashed line.
Varieties CI 41-223, CI 49-200, CI 54-312, CI 61-205, and CI 65-294 were screened at 3 lbs. Polaris/A (Table 2 ) . Of this group, CI 61-205 and CI 65-294 showed the greatest potential for response with increases in yield of 1.59 points (13.7%) and 2.12 points (19.0%), respectively. CI 41-223 and CI 54-312 increased 1.14 points (9.5%) and 0.59 points (5.1%) in yield, respectively, with treatment. CI 49-200 had the lowest response with an increase of 0.17 points (1.8%) in yield.
Al "CI" varieties in the 1977-78 commercial tests were rated responsive except one. The yield in- creases for CI 54-336, CI 54-378, CI 65-260, CI 61-5, and CI 65-279, which were in replicated tests, are considered more reliable. The results with the first four of these generally agree with previous tests.
This was the first experience with CI 65-279. CI 59-1052 gave a significant response when the 3, 3.5, and 4 lbs/A rates were pooled. Past tests with this variety at 3 lbs/A had given erratic results. We speculate that a more consistent response may be obtained at the higher rate of 4 lbs/A. The response of CI 41-223 and CI 54-312 generally agrees with past reports (4) and our experience, while lack of response in CI 49-200 conflicts with past experience. This was the first experience with CI 61-205 and CI 65-294, both of which showed outstanding potential for response to the ripener.
Small Plot Screening. All varieties in the small plot screening tests increased in yield with Polaris treatment, but the range of responses was from very small to large (Table 3 ) . CI 59-1052 showed little response in the small plots when treated with 3.5 lbs Polaris/A. At 4 lbs/A, the average yield increase was 0.45 points (3.9%), which was not significant, although the individual replications were consistent for the trend. CI 65-260 averaged 0.46 points (4.0%) increase in yield when treated at 3 lbs Polaris/A.
The increase was consistent in the replications but not significant. CI 65-294 increased 1.03 points (9.2%) in yield with Polaris, which was highly significant. The yield of CI 65-279 averaged 0.52 points (4.3%) higher in the treated plots. CI 61-620 averaged 0.46 points (4.4%) increase in yield with Polaris, and CI 68-575 averaged 1.3 points (12.6%) increase in yield with treatment. As in the commercial tests, there were general increases in brix, sucrose, and purity.
Table 3. Comparison of Polaris treated and check cane of seven varieties in small plots.
Polaris 0
rate No. Crusher Juice Yield 96 sugar, Variety (lbs/A) Replications Brix % Sucrose % Purity % cane CI 59-1052
CI 59-1052
CI 65-260
CI 65-294 CK 3.5 Change
CK 4 Change
CK 3 Change
CK 3 Change
4 4
4 4 4 4
4 4
21.41 21.84 + .43 21.08 21.68 + .60 20.95 21.45 + .50 20.30 21.80 1.50**
19.64 20.07 +.43 19.21 19.90 + .69 19.14 19.80 + .66 18.41 19.99 1.58**
91.69 91.89 +.20 91.09 91.77 + .68 91.34 92.32 + .98 90.68 91.70 +1.02
11.83 12.11 + .28 11.54 11.99 + .45 11.48 11.94 + .46 11.15 12.18 +1.03**
CI 61-620
CI 65-279
CI 68-575 CK
3 Change
CK 3 Change
CK 3 Change
2 2
2 2 2 2
19.82 20.55 + .73 21.20 21.95 + .75 19.92 22.22 +2.30
17.79 18.52 + .73 19.48 20.48 +1.00 17.98 20.17 +2.19
89.77 90.12 + .35 91.86 92.26 +.40 90.30 90.76 + .46
10.54 11.00 + .46 12.12 12.64 + .52 10.28 11.58 +1.30
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The yield increases for varieties CI 59-1052, CI 65-260, CI 65-279, and CI 65-294 with Polaris treatment in small plots were about half of those obtained in the commercial trials. Considering that CI 65-260 is generally responsive, the results with the other varieties are promising. The smaller increases were pro- bably due to sucrose levels being naturally high. Varieties CI 61-620 and CI 68-575, both of which will be planted commercially for the first time in the fall of 1978, were screened for the first time. CI 61-620 showed potential, and CI 68-575 showed outstanding potential for response to Polaris.
REFERENCES
1. Baird, D. D., Personal communication. Monsanto Agricultural Products Company, St. Louis, MO 63166.
2. Arceneaux, G. 1935. A simplified method of making theoretical sugar yield calculations in accordance with the Winter-Carp-Geerlings formula. ISJ 37:264-5.
3. Bourne, B. A. 1968. Important key which aided greatly the sugarcane research work in Florida. The Sugar Journal 30(8):11-13 and 30(9):29.
4. Orsenigo, J. R. Polaris and sucrose enhancement in Florida sugarcane. Proceedings Sugarcane Ripener Seminar. Rio de Janeiro, Brazil. September 9, 1977. pp. 65-68.
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MATURITY PATTERNS OF SEVERAL LOUISIANA SUGARCANE VARIETIES
C. A. Richard American Sugarcane League
New Orleans, La. and F. A. Martin and G. M. Dill Louisiana Agricultural Experiment Station
Baton Rouge, La.
ABSTRACT
Maturity data on six commercial sugarcane varieties were collected for three years at the St. Gabriel Farm of the Louisiana Agricultural Experiment Station. Yield components were evaluated throughout the harvest season for both plant and stubble cane. Varietal differences agreed with previously reported maturity classes. Stubble cane was found to have higher initial sucrose and purity than plant cane; however, the rate of sucrose accumulation and increase in stalk weight was greater for plant cane during the harvest season. These data therefore supports the practice of harvesting stubble cane prior to plant cane in Louisiana in order to allow for the greater potential increase of the plant cane crop.
INTRODUCTION
Testing of Louisiana commercial sugarcane varieties in infield, outfield, and maturity test have indicated differences in the relative maturity of these varieties. Although these evaluations are routinely harvested by stubble age (plant cane crop or stubble cane c r o p ) , variety and harvest recommendations make little reference to stubble age (8). Consequently, commercial fields of sugarcane are in some cases, scheduled for harvest based on sucrose level rather than stubble age. Therefore, during several harvesting seasons at the LSU Agricultural Experiment Station, St. Gabriel Farm, changes in juice quality and growth rate were monitored to determine:
1. The maturity patterns of sugarcane genotypes with particular reference to crop, and 2. The validity of using only sucrose percent in establishing harvest schedules.
MATERIALS AND METHODS
Commercial and experimental varieties are routinely grown at the St. Gabriel Farm of the Louisiana Agricultural Experiment Station. During the 1974 through 1977 harvest seasons, replicated plots of plant and stubble cane of six commercial varieties (Table 1) were sampled biweekly.
Ten stalk samples were cut flush with the ground, stripped, topped through the apex, weighed, and milled once through a 3-roller mill. For each juice sample, brix was determined by hydrometer, apparent sucrose by polarization, and apparent purity as the ratio of apparent sucrose and brix (13). From these results, the yield of recoverable sugar per ton of cane was calculated by a method previously described (12). The yield of cane per acre was calculated by multiplying mean stalk population per acre by mean stalk weight. Finally, the yield of recoverable sugar per acre was calculated by multiplying recoverable sugar per ton by yield of cane per acre.
There was an average of 38 data points for each variable over the six varieties during the four year period. These variables were analyzed by least squares analysis to determine the best models to relate harvest date and each yield component of interest. These models were used to compare maturity patterns of plant and stubble crops of the six varieties of interest.
RESULTS AND DISCUSSION
Data for stalk weight best fit a linear model while data for normal juice sucrose, sugar per ton and sugar per acre best fit a quadratic model (Table 2 ) .
Biweekly values taken from the best fit curves of normal juice sucrose for the six varieties in both plant cane and stubble cane are shown in Table 3. Two of these varieties, NCo 310 and CP 61-37 are late maturing (2,4) and their sucrose values in this data did not exceed 12.6% in either crop. Two other va- rieties, CP 67-412 and CP 48-103 have been classified as mid-season maturing varieties (7,3). The data would indicate this to be true since these two have generally higher sucrose values at midseason (Nov. 12) than do the two late maturing varieties. Both CP 65-357 and L 62-96 have been classified as early maturing (6 5) and again this data shows that generally these two varieties have higher sucrose than do the other four va- rieties in the early dates of the maturation season.
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Of more importance is the pattern of maturity of these varieties with respect to crop. It should be noted that the stubble sucrose of each variety generally starts higher than the plant cane sucrose and con- tinues its advantage throughout the season. This is generally accepted as fact for Louisiana sugarcane.
The value of 12% normal juice sucrose has been accepted in Louisiana as par sucrose value ( 1 ) . The date at which each variety reaches par sucrose was taken from the predicted values of normal juice sucrose and can be seen in Table 4. This summarizes the relative maturity of each of the varieties and the differences b e - tween stubble cane maturity and plant cane maturity.
The values of sugar per ton of cane nearly paralleled differences in normal juice sucrose since a very strong association between sucrose and sugar per ton exists (11).
From Table 4 a decision can easily be made as to which cane is best at the early harvest dates and which cane is suited for the late harvest dates. However, at mid-season (third week of October to the third week of November) there are some decisions to be made. Looking only at maturity dates a harvest schedule based solely on sucrose percent would result in the plant cane of the early maturing varieties being harvested b e - fore the stubble cane of the late maturing varieties. However, if one considers all yield components, does harvesting plant cane of the higher sucrose varieties before stubble cane of the lower sucrose varieties actually produce higher profits in the current harvest season?
Table 5 shows the average percent weight increase of the six varieties for the two crops during the maturation period. There is an average of 2% faster growth rate in the plant cane crop over the stubble cane crop. Although not statistically different, the early maturing varieties tended to increase in stalk weight slightly faster than the late maturing varieties. This would suggest that early harvest of the plant cane crop would subtract from the full tonnage increase potential. Thus, following only juice quality guide- lines for a harvest schedule might not be allowing for the greatest potential increase in crop yields, especially when comparing the percent increase of the plant cane of early maturing varieties with the stubble cane of the late maturing varieties.
For further examination of this point, Table 6 shows sugar per acre. This would approximate a value for payment of sugarcane deliveries. As previously indicated the practice of harvesting older stubble of the highest sucrose varieties in the early portion of the harvest season and the plant cane of the lowest sucrose varieties in the later portion of the harvest season is already followed. These two classes of varieties are the data in the upper right and lower left hand columns of Table 6. The two classes of canes where the decision on harvest schedule is to be made are the plant cane of the early maturing varieties (upper left hand columns) and the stubble cane of the late maturing varieties (lower right hand columns). These decisions are generally made from late October to mid-November. Therefore, for each crop of each class of varieties the sugar values for October 22 and November 21 are listed.
If the harvest schedule were dictated solely by sucrose level, then the plant cane of the early matur- ing varieties (yield of 6954 lbs. of sugar) would be harvested early and the stubble of the late maturing varieties (yield of 6360 lbs. of sugar) would be harvested later. This would produce a total theoretical yield of 13,314 lbs. of sugar. However, if the harvest schedule were designed primarily by crop, then the stubble cane of the late maturing varieties (yield of 5068 lbs. of sugar) would be harvested early and the plant cane of the early maturing varieties (yield of 8253 lbs. of sugar) would be harvested later. This would produce a total theoretical yield of 13,321 lbs. of sugar. These two totals can be considered practi- cally the same. Therefore, there would be no overall yield or profit increases by following only a sucrose scheduling of the harvest plan. This might result in a penalty for shipping sub-par sucrose cane while harvesting stubble of late maturing varieties in the early part of this mid-season period, but during this time the yield of the plant cane of the early maturing varieties has increased at a faster rate and to a higher level than if the reverse schedule has been followed.
It should also be considered that early harvest of the plant cane crop is damaging to the subsequent stubble crop yields (10).
There may be valid reasons for harvesting plant cane early. However, they would be logistically re- lated reasons such as poorly drained heavy soils, inaccessibility in the late harvest season, etc. As previously stated, plant cane harvested after mid-season generally produces better stubble yields in subsequent crops. These data would indicate that there is no profit increase by harvesting plant cane of early varie- ties before stubble cane of late varieties. The practice of using only sucrose percent to schedule individual field harvesting is not sound. However, scheduling of field harvest based primarily on crop followed by sucrose percent may be acceptable.
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Table 2. Best models for the relationship between yield components and time.
Table 3. Predicted values of normal juice sucrose for six varieties across harvest dates.
Table 5. % weight increase from Oct. 12 to Dec. 1.
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Table 1. Varieties included in this study and the % of the state's acreage they occupied in 1978.
Table 4. Dates at which varieties reached par sucrose (12% N J S ) .
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Table 6. Yields of sugar per acre for six varieties on two harvest dates in the two crops.
Plant cane Stubble cane Variety Oct. 22 Nov. 21 Oct. 22 Nov. 21
L 62-96 8897 10162 5320 6383 CP 65-357 7664 9222 6266 7752 CP 48-103 4301 5374 4629 5691 x 6954 8253 5405 6609 CP 67-412 5683 7000 5356 7303 CP 61-37 5329 7106 5273 5994 NCo 310 5325 6835 4574 5782 x 5446 6980 5068 6360
REFERENCES
1. • ASCS Handbook. Sampling, testing and reporting for Louisiana sugar processors. 8-SU Revision 1. USDA, Washington, D. C.
2. . 1954. Release of new sugarcane variety NCo 310. Sugar Bull. 32(19): 294.
3. . 1955. Release of new sugarcane variety CP 48-103 and CP 47-193. Sugar Bull. 33(20):
285.
4. . 1967. Notice of release of sugarcane variety CP 61-37. Sugar Bull. 45(20): 271.
5. . 1969. Notice of release of sugarcane variety L 62-96. Sugar Bull. 47(20): 3.
6. . 1973. Notice of release of sugarcane variety CP 65-357. Sugar Bull. 51(20): 4.
7. . 1975. Notice of release of sugarcane variety CP 67-412. Sugar Bull. 53(19): 5.
8. . 1978. Sugarcane variety recommendations for Louisiana for 1978. Sugar Bull. 55(22):
14-16.
9. Arceneaux, George. 1935. Studies of ripening of sugarcane in Louisiana and of effect of topping upon yields of cane and sugar per acre. USDA Circular No. 368.
10. Hebert, Leo P. and L. G. Davidson. 1960. Effect of time of harvest on yields of sugarcane and sugar at Houma, Louisiana, from 1953 to 1956. Sugar Bull. 38(17): 215-219.
11. Legendre, B. L. 1970. Associations involving yield of sugar per acre and its components in sugarcane.
Unpublished Ph.D. Dissertation . Baton Rouge, Louisiana, Louisiana State University.
12. Legendre, B. L. and M. T. Henderson. 1972. The history and development of sugar yield calculations.
Proc. ASSCT. 2(NS): 10-18.
13. Meade, G. P. 1963. Spencer-Meade Cane Sugar Handbook. (8th ed.) John Wiley and Sons, Inc. New York.
14. Richard, Charles A., Hugh P. Fanguy, Donnie Garrison, Windell Jackson and Howard Robichaux. 1978.
Sugarcane variety outfield experiments in Louisiana during 1976. Sugar Bull. 56(15): 14-18.
METHODS FOR DISPOSING OF UNHARVESTED SUGARCANE AND THEIR INFLUENCE ON SUBSEQUENT PRODUCTION
G. Kidder and B. R. Eiland Florida Cooperative Extension Service and USDA
Belle Glade, Florida
ABSTRACT
Sugarcane killed by freezing temperatures frequently deteriorates to the extent that it is not eco- nomically harvestable and becomes a disposal problem. Effects of the disposal method on subsequent cane and sugar production were investigated. Before treatments were applied, one set of plots was burned, but the other was not. Treatments consisted of leaving the stalks standing, running a tractor wheel over the row of standing cane, running a rolling chopper-drum over the cane, and mowing with a rotary mower. Under both burned and unburned conditions, subsequent cane and sugar yields were lowest where the cane was left standing and highest where it was run over with the tractor wheel; differences between the standing treat- ment and the three disposal treatments were greater than differences among the disposal methods. No sig- nificant differences in sugar content of the cane were found. Burning prior to applying the disposal treatments resulted in somewhat higher sugar and cane yields in the subsequent crop than not burning.
The unharvested cane did not present any serious problems in mechanical harvesting of the subsequent cane crop but dead stalks were observed in all harvested samples and would be a factor in commercial harvesting and processing of cane.
INTRODUCTION
Mature sugarcane killed by cold temperatures is generally harvested for some time after a freeze, de- spite lowered quality and reduced sugar recovery. Occasionally, however, the quality of the frozen cane becomes unacceptable before the mills can process all of it and some cane is not harvested.
Most of the sugarcane growing in Florida in January 1977 was killed during several nights of freezing temperatures. Although badly frozen cane was milled as long as 7 weeks after the freezes, about 4000 hectares of frozen cane was left unharvested. Sugarcane producers were then interested in the best method for disposing of the unharvested cane.
In Louisiana (3) some growers cut the cane down by backing a rotary mower into the standing cane after burning it. Other growers simply burn the standing cane. They have found that subsequent tractor operations flatten most of the stalks, and few problems arise in the subsequent harvest. Where small areas are concerned, some growers dispose of the cane by cutting it and hauling it from the field.
The method of treating young freeze-damaged sugarcane has been shown to influence yields (1, 2, 4 ) . However, no references could be found to document the effects of disposal methods in mature cane on the yield of the subsequent sugarcane crop. Some methods for disposal of unharvested cane could conceivably be harmful to the subsequent cane crop, as well as expensive and energy intensive. Interference with subsequent field operations is another factor that should be considered.
The objectives of the study reported here were: 1) to compare cane and sugar yields in plots where, in the previous crop year, unharvested cane had been disposed of by different means and 2) to compare cane and sugar yields when cane was burned and not burned before stalk disposal.
MATERIALS AND METHODS
A small field of 10-month-old variety CI 41-223, plant sugarcane that had been killed by the January 1977 freezes was used for the experiment. The cane, which was grown at the Agricultural Research and Education Center at Belle Glade, was uniform and generally erect. Yield was visually estimated at 130 tonnes of cane/ha.
Sixteen adjacent rows of cane were selected for the disposal experiment.
On March 15, 1977, alleyways were mowed across the field to form eight blocks. Standing cane in the four blocks on the southern half of the field was burned, and that in the blocks on the northern half was left unburned. Two randomized complete block experiments with four treatments and four replications were installed, one on each half of the field. Each plot was 6.0 meters (4 rows) wide by 15 meters long. Treatments, per- formed March 17 and 18, consisted of: 1) leaving the stalks standing, 2) running a tractor wheel over the row of standing cane, 3) running over the cane with a rolling chopper-drum (known locally as a "devil catcher"), and 4) mowing with a rotary mower. An 83-KW hydrostatic tractor equipped with dual wheels was driven at 10 to 16 kph for running over the cane and for pulling the rolling chopper-drum. The "devil catcher" consisted of two steel cylinders, 60 cm in diameter and 1.5 m long, with eight equally spaced, tranverse blades protruding 15 cm from the drum. A 1.8-m rotary mower powered by a 34-KW single-wheeled tractor was used for the mowing treatment.
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