THINGS I WORRY ABOUT
SES 60-4-6 SES 196
SES 351 Coimbatore Krakatau SES 6 SES 205-A Djatiroto Kinggoerang Oewis US 4639
Related genera Erianthus bengalense (retz.) Hubb & Vaughan Narenga porphyrocoma (Hance) Bor Sorghum bicolor (1.) Moench
Miscanthus sinensis Anders (US 59-289)
Miscanthus hybrid (US 64-53-2)
0.22 0.30 0.33 0.36 0.38 0.40 0.41 0.42 0.46 0.51 0.38
0.40
0.43
0.50
0.53
0.50
The areas per unit of weight of 9 varieties of S. officinarum also averaged 0.3 dm2/g, ranging from 0.28 to 0.33 dm22/g (Table 1 ) . The area per unit of weight of 0.3 dm2/g could be used for most com- mercial and experimental clones of the same age, growing under similar conditions.
The areas per unit of weight of 10 varieties of S. spontaneum averaged 0.4 dm 2/g, but ranged from 0.22 to 0.51 dm2/g. Leaf morphology also varied in this group. The varieties US 60-4-6 and Coimbatore have very narrow leaves, the former having only vestiges of lamina. The varieties Krakatau and Kinggoerang Oewis have broad leaves, similar to those of the Saccharum hybrids.
The areas per unit of weight of related genera were slightly higher than those of Saccharum, averag- ing 0.5 dm2/g and ranging from 0.40 to 0.53 dm2/g. While US 60-4-6 had the most narrow leaves and the lowest area per unit of weight, the leaves of "sorghum were the widest, with nearly the highest area per unit of weight. This suggests that area per unit of weight may be related to leaf width and thickness,
CP 65-332 CP 28-11 CP 66-315 La. Purple POJ 213 Krakatau SES 196 Djatiroto US 4639 Kinggoerang Oewis
0.24 0.32 0.32 0.32 0.32 0.36 0.38 0.40 0.48 0.49
1.19 1.04 1.02 1.19 1.17 1.12 1.01 1.10 1.34 1.46
Since area per unit of weight showed little variation, it is permissible to use a constant (0.3 dm2/g) for varieties commonly encountered in commercial or experimental fields. The area per unit of weight could then be used in determining total leaf area by using the formula:
A = SW,
where A is the total leaf area, S is the area per unit of weight (0.3 dm2/g), and W is the weight of leaf blades (g). A 0.0247 ha (0.01 acre) plot of cane that contained 300 stalks is typical of Louisiana fields. A 10-stalk sample may yield leaves weighing 980 g. The formula above would give an area of 294 dm2 of leaves for the 10 stalks, or 88,200 dm2 or 882 m2/gr the plot, or 3.6 ha of leaves/ha of land.
Caution should be used in applying the value shown for area per unit of weight to cane leaves from other soil types or other stages of growth. Changes occur in the relation of leaf area to leaf weight in different growth stages (1). When using fresh leaves for determinations of area per unit of weight, care must be used to avoid errors cuased by changes in water content.
REFERENCES
1. --Roller, H. R. 1972. Leaf area-leaf weight relationships in the soybean canopy. Crop Sci.
12:180-183.
2. Watson, D. J. 1937. The estimation of leaf area in field crops. J. Agr. Sci. 24:474-483.
FLORIDA SUGARCANE ATTACKED BY WHITE GRUBS IN 1972 T. E. Summers
ARS-USDA Canal Point, Florida
During late August and early September, near-mature sugarcane plants were observed dying and filling over as a result of the destruction of their roots by a large white grub identified as Eothymus subtropicus. The size of affected areas varied from a few square yards to entire 20-acre fields. Good control was obtained by field flooding continuously for 144 hr.
s available for the Proceedings.
MASS REARING THE SUGARCANE BORER R. D. Jackson Southern Region, ARS, USDA
Houma, Louisiana
ABSTRACT
A facility has been developed at the Houma Station for mass-rearing of the sugarcane borer, (Diatraea saccharalls (F.) ), on an artificial diet under controlled conditions. After the eggs are laid and hatched, the first instar larvae are transferred to individual compartments (1.25 x 1.25 x 3.75 cm) of a partitioned tray (30 x 60 x 2.5 cm) which have been filled two-thirds full of a prepared pinto-bean diet. The trays are then closed so that each compartment is sealed with bronze screen and polyurethene foam padding. The closed unit is placed in a controlled temperature room at 29 C. After 25 days the trays are opened and the pupae are transferred to vented containers for emergence. The moths are collected with a power aspirator into cylindrical cages lined with wax paper. The moths oviposit eggs in masses on the wax paper liner. The eggs are collected daily by changing the liners and punching out 1.25 cm disks of the paper with an egg mass adhering to each disk. The eggs are held in controlled environment at 26-27 C and 85-95% RM until they are ready to be used for plant-resistance research, rearing parasites, parasite-host interaction studies, or to rear more moths for the parent culture or for irradiation research. In a 4-week period, 200,000 egg masses can be produced using one 8 x 12-ft and two 8 x 8 controlled temperature rooms, one 8 x 12-ft diet preparation room and one 12 x 13-ft work room.
Editor's note: Only the Abstract of this paper was available for the Proceedings.
L 60-14, A TROPICAL SUGARCANE VARIETY Manuel Coronel, Felipe Chui, and S. J. P. Chilton
The variety L 60-14 was introduced at Ingenio San Antonio, Nicaragua, Central America, in 1965.
Small plot tests demonstrated its possibilities as an early-to-medium cane. It was increased com- mercially in 1970-1971. In 1971-1972, it averaged 45.7 tons to the acre on 3,378 acres and 49.1 tons per acre on 5,598 acres through March 20, 1972-1973. Average yields of all fields at the Ingenio were 42.6 tons in 1971-1972 and 44.9 tons in 1972-1973 through March 20. Estimated sugar recoveries by use of crusher juice analyses through March 20, 1971-1972 and 1972-1973 were 209.39 pounds and 192.02 pounds for L 60-14. Estimated sugar recoveries of all varieties were 205.40 pounds of sugar per ton of cane in 1971-1972 and 190.25 pounds of sugar per ton of cane in 1972-1973 during the same period.
L 60-14 appears to be a good early-to-medium (November-February) variety for tropical areas. It is planned to increase this variety to 9,600 acres of a total 20,000 acres for the 1973-1974 harvest.
Editor's note: Only the Abstract of this paper was available for the Proceedings.
EFFECT OF FROST ON CERTAIN SUGARCANE VARIETIES GROWN IN THE LOWER RIO GRANDE VALLEY OF TEXAS
Kenneth A. Sund
Texas A&M University Agricultural Research and Extension Center Weslaco, Texas
and B. A. Smith
Food Crops Utilization Unit, A.R.S., U.S.D.A.
Weslcao, Texas
ABSTRACT
On Jan. 12 and 13, 1973, temperatures dropped to 26 and 29 F, respectively, killing the meristems of sugarcane planted in the Rio Grande Valley of Texas. Eye damage was moderate to severe on 6 of the 7 varieties selected for commercial planting, but little damage was caused to the lateral buds of the seventh variety, NCo 310. Juice data indicated that the peak recoverable sugar measured in 18 varieties under evaluation occurred prior to the chilling period with 245 lb/T. After the frost, recoverable sugar gradually decreased to 200 lb/T by Mar. 12. A second period of frost of similar intensity occurred on Feb. 9 and 10, and most of the lateral eyes of the 6 varieties, which had been stimulated to germination, were killed, and planting material became largely unavailable. Three of the varieties included in these studies showed evidence of rapid deterioration in juice quality following the second freeze, as measured by disappearance of sucrose and an apparent increase in ash % solids.
INTRODUCTION
The new sugarcane industry in South Texas faces certain problems such as optimum use of water and some saline soils, both of which man has learned to cope with and control. One other that is common to the sugarcane areas of the continental USA, but beyond man's control, is sub freezing weather.
A high probability of severe and early freezes limits the sugarcane processing season to about 65 days in Louisiana, but the reduced incidence of these conditions permits a longer processing season in Florida. The winter climate in the lower Rio Grande Valley of Texas more closely resembles that of Florida than that of Louisiana. Nevertheless, severe winters can be expected in South Texas, and while the probability of extreme minimum temperatures is somewhat less than in the cane area of Florida, the lowest recorded temperature of this area of Texas is lower than that reported from the Florida cane area, and severe freezes in Texas have been of longer duration.
Of several factors that determine the extent of freeze damage to cane, two of the most important are intensity and duration of the freeze. A third, which man can control to some extent, is the selection of varieties that are more cold tolerant and thus remain more millable following moderate freezes.
The effects of light freezes on sugarcane are well known (5, 6, 7, 8 ) . Indications are that freezes which kill leaves, apical meristems, and the upper lateral buds essentially stop the photosynthetic pro- cesses but cause only slight deterioration in the quality of the cane juice. The occurrence of tempera- tures of 26 to 29 F on Jan. 12 and 13, and again on Feb. 9 and 10, provided an opportunity for evaluation of the effects of mild freezing conditions on a sugarcane nursery in the Lower Rio Grande Valley of Texas, which included the 7 varieties selected for commercial planting in this area and several newer varieties.
METHODS
On Monday following the frost of Jan. 12 and 13, selected varieties were cut, stripped and divided into top, middle and bottom sections of the stalks. Borer-damaged eyes were rejected, and the remainder were placed in tubs containing a mixture of.1 1/2 bags of soil conditioner to 1 bale of peat moss. After watering, the tubs were maintained at 65 F in a greenhouse. Sprouting of eyes was recorded weekly for a period of 2 months, and percent germination of eyes noted.
For studies of juice quality, 20-stalk samples of each variety were passed once through a 3-roll, cane-sampling mill hydraulically loaded to provide a pressure of 30-33 tons of force on the upper roll.
Extracted juices were screened through a 100-mesh screen, mixed, weighed, and sampled. Analyses of the crusher juices were conducted according to standard methods of the sugarcane industry, including spindle brix readings of solids content, polarization of a 26-g sample, and free acidity values as ml of 0.1 N NaOH required to titrate 10 ml of juice to pH 8.3. Free acidities were also expressed as % aconitic acid on brix solids, since there was evidence of the disappearance of juice solids in some materials. Carbonate ash was determined according to Method I of the AOAC (1), except for ignition at 550 C instead of 525 C, and the weight of ash was expressed as % on brix solids. Apparent purities were calculated values where sucrose, as measured by polarization, was expressed as % on brix solids.
RESULTS Germination of Lateral Eyes.
The effect of the Jan. frost on the viability of lateral eyes was determined on the following vari- ties: CP 44-101, CP 52-68, CP 55-30, CP 61-37, L 60-25, L 62-96 and NCo 310, as these are the commercial canes selected for the first milling season in Texas.
The variety NCo 310 had outstanding tolerance to frost, with an overall 93% germination of lateral eyes on the entire stalk (Table 1 ) . In general, top eyes were more severely damaged than bottom eyes;
thus, the percent germination for CP 44-101 was 36.9, 64.2 and 89.1% from the top, middle and bottom thirds of the stalks respectively. The buds of the varieties L 62-96, CP 55-30 and CP 52-68 were particularly susceptible to cold injury, with the latter variety showing only 24.5% viable eyes.
Table 1. Percentage germination of lateral eyes on stalks of 7 sugarcane varieties following frost.
Portion of Stalk
Variety Top 1/3 Middle 1/3 Bottom 1/3 Overall NCo 310 98.1 90.4 91.2 93.3 CP 44-101 36.9 64.2 89.1 63.9 L 60-25 32.6 76.7 73.1 58.2 CP 61-37 79.3 21.1 36.8 50.3 L 62-96 37.7 28.6 54.8 39.2 CP 55-30 31.5 36.7 50.6 39.2 CP 52-68 12.1 12.5 44.7 24.5
CP 57-614 L 64-1 L 62-96 CP 56-59 CP 61-37 L 66-48 CP 65-357 L 61-52 CP 59-73 L 60-14 L 61-43 L 66-15 CP 60-1 CP 62-374
4 5 5 6 6 5 6 5 6 5 5 5 5 6
21.99 19.83 19.68 19.68 18.71 18.80 19.54 18.37 19.34 20.11 19.52 18.75 18.84 18.06
19.2 17.3 17.0 17.0 16.0 16.0 16.6 15.6 16.4 17.0 16.5 15.7 15.7 14.8
87 87 86 86 85 85 84 84 84 84 84 83 83 82 5 4 4 1 7 2 7 7 6 6 5 7 4 0
2.14 1.46 1.65 1.36 1.83 1.90 2.00 1.57 2.10 2.28 2.23 1.36 2.27 2.11
3.52 3.74 3.94 3.64 3.85 3.89 4.50 4.54 4.33 4.01 4.45 4.30 4.79 4.62 Effect of Freeze on Estimated Recoverable Sugar.
Certain varieties had been selected previously to determine their ripening characteristics. One group of 9 varieties, together with NCo 310, was harvested on Oct. 30 and every other week until Mar. 19.
A second group of 9 varieties, and NCo 310, was harvested on alternate weeks.
Analyses of the crusher juices obtained from the monthly harvests of the 20 sugarcane varieties re- vealed that 13 maintained juice purities of 80% or higher during the 5-month harvest period. The trials were not designed with sufficient replications to allow reliable month by month evaluation of each variety, but the averages of the monthly analytical data for each variety (Table 2 ) , afforded means for comparing the performances of these canes under the conditions prevailing during this period. The varieties are listed in Table 2 in the order of decreasing average crusher juice purities. Except for L 66-48 and CP 62-374, where brix, pol, and purity showed no significant change throughout the harvest period, the juices of most varieties indicated that some degree of deterioration had occurred by the time of ????
or Mar. harvests, so that averaged values of brix, pol and purity in this table were slightly less than the maximum levels detected.
Table 2. Seasonal average crusher juice composition for 13 sugarcane varieties exhibiting minima- response to frost damage.
Carbonate No. Free ash Variety harvests brix pol purity acidity (% bx)
The free acidities (Table 2) showed no particular correlation with other data. Values taken at the monthly harvests of each variety were reasonably constant throughout the 5-month period, and tend to re- affirm the observations of Fort and McKaig (2), and Irvine (4) that the acidities of cane juices reflect varietal response to environmental factors.
Carbonate ash values (Table 2) were noted to be generally higher for the varieties which provided lower purity juices. With some of the varieties listed, the higher ash contents may reflect failure of the cane to reach maximum maturity, but with the higher purity varieties, the ash contents, no doubt, rep- resent varietal response to the environmental factors, as noted by Fort and McKaig (2).
Three of the cane varieties in these trials, L 65-69, L 62-86), and L 64-67, exhibited marked re- sponses to freezes, as measured by brix, pol, and purity decreases at the time of the Mar. harvest.
Analytical data from these varieties are presented in Table 3, where the first line for each variety pro- vides average data for all harvests prior to Mar., and the second line the data from Mar. harvest only.
Small decreases had been detected in brix, pol, and purity values for each variety by the time of the Feb.
harvest, but all purities still exceeded 80%. By Mar., however, juice deterioration had become signi- ficant, L 65-69 to the greatest degree, followed by L 62-86, and to the least degree L 64-67. The type of deterioration noted with the 3 varieties reported in Table 3 did not involve fermentation, and the free acidity values showed no significant increase between Feb. and Mar. harvests.
L 65-69 L 62-86 L 64-67
5 1 4 1 4 1
19.49 13.32 18.54 14.76 18.61 16.49
15.9 9 . 4 15.7 11.5 15.4 13.0
81.6 70.6 84.4 77.9 82.8 78.8
2.48 2.27 1.49 1.88 2.14 2.03
4.99 7.95 4.96 6.24 4.76 5.91
Juice carbonate ash content of the 3 varieties in Table 3 for the period prior to the Mar. harvest were generally higher than those listed in Table 2, and the significant increases which occurred by the time of the Mai- . sampling date indicated that the loss of brix solids was principally a loss of organic
matter, such as sucrose.
Data from juice analyses were used to calculate pounds of recoverable sugar per net ton of cane, which are presented in Fig. 1 as a statistically derived quadratic equation for all varieties taken to- gether. In the latter, x represents tenths of a week and the whole expression is given in logarithms to the base 10. The variety NCo 310 was deleted from these data since there was considerable rat damage to the stalks.
Table 3. Seasonal average crusher juice composition for 3 sugarcane varieties exhibiting measurable response to frost damage.
No. Carbonate Harvests Free ash
Variety Averaged Brix Pol Purity acidity (% bx)
The frost periods of Jan. 12-13 and Feb. 9-10 decreased the overall recoverable sugar of the 18 varieties from peak values exceeding 240 lb per ton in late 1972 to 200 lb per ton by Mar. 12. Data ir Table 4 indicate that the varieties CP 65-357, L 62-96, L 60-14, L 66-48, and L 64-1 appeared to have especially good keeping quality, but L 64-67, L 62-86, and L 65-69 appeared to be poor in this respect.
Although the data for CP 57-614 and CP 57-603 were less complete, they indicated that these varieties had good tolerance to cold.
Table 4. Pounds of sugar per net ton of cane at several dates of sampling.
Variety CP 57-614 CP 57-603 CP 65-357 L 62-96 CP 59-73 CP 61-37 CP 56-59 CP 62-374 CP 55-30 L 65-69
10/30/72 284.0 238.6 258.0 257.7 234.4 257.0 199.7 199.5 221.3
11/27/72 292.8 242.1 277.1 246.4 256.6 277.3 236.3 191.4 231.1
Date 12/18/72 281.7 261.3 273.4a
252.3 248.3 262.5 223.9 193.4 241.8
1/22/73 274.4 235.4 259.2 237.7 234.4 265.2 183.6 192.0 232.0
2/19/73
211.8 237.2 230.9 219.8 221.0 221.3 222.7 179.4 204.9
3/19/73
246.2 224.7 220.5 209.3 208.7 203.4 201.1 149.4 122.4
Variety L 60-14 L 66-48 L 64-1 L 61-43 L 66-15 L 61-52 CP 60-1 L 64-67 L 62-86
11/13/72 263.1 238.8 271.1 254.0 245.1 238.2 251.6 228.9 222.6
12/11/72 248.3 227.1 264.3 251.6 209.0 226.6 244.8 229.1 231.9b
Date 1/8/73 258.5 243.4 271.5 251.7 233.7 240.9 240.1 220.1 227.3
2/5/73 228.4 233.3 250.0 220.3 235.3 221.0 210.3 204.4 186.9
3/5/73 234.7 223.1 220.0 216.9 205.7 201.1 186.0 181.3 159.3
DISCUSSION
Low temperatures such as those experienced in the winter season of 1972-73 were unusual for the Lower Rio Grande Valley of Texas and had not occurred since 1963, when minimums of 27 and 23 F were recorded on the 13th and 24th of Jan., respectively. Such temperatures would probably mean that most seed cane would be unsuitable for planting. This farming operation can not be delayed without risk of poor stands and loss of viable seed.
In 1973, the temperatures were recorded at a height of 5 ft. Since the frost had been preceded by rainy weather, the moisture on the ground undoubtedly had a mitigating effect on cold air tempera- tures at ground level. Although the bottom eyes of most varieties can be assumed to be more tolerant to cold than those near the top, a cold spell could be expected to be more injurious during a dry spell than when conditions are moist.
A variety such as NCo 310, which tends to lodge easily, may be less exposed to low temperatures that hover a few feet above the ground. Coleman(1) observed in Louisiana that frost damage was greater in lodged cane under dry conditions due to loss of protection by the leaf canopy. Nevertheless, there seemed to be real differences among varieties in susceptibility to damage by cold. Thus, the bottom third of the stalks of NCo 310 and CP 44-101 had more viable eyes after the freeze than stalks of CP 55-30 and CP 52-68. This was also borne out by the experience of growers who were forced to plant late. Data for the variety CP 61-37 showed good viability in the top third of the stalks and poor in the remainder. None of the canes had been sprayed against the borer and infestation was especially heavy in this variety, a factor which undoubtedly contributed to poor germination.
a 12/11/72
(1)Private communication. R. E. Coleman, U.S.D.A., A.R.S., Beltsville, Maryland
b 12/18/72
The cold weather that can be expected at latitudes of 28 to 32° on either side of the equator, ac- centuates the need for early-maturing cane varieties. Generally, recoverable sugar of most varieties of sugarcane grown in these latitudes will not peak out in Mar. or Apr. So far, no varieties have indicated this in the Lower Rio Grande Valley of Texas. In Iran, the purities of juices from commercial varieties did not peak out until May, when they reached 92 to 93% with brix values over 20.
The selection of cane varieties with a significant degree of cold tolerance also would be important from the standpoint of factory performance. Deterioration in juice quality, similar to that observed with L 65-69, L 62-86, and L 64-67, would seriously impair sugar production, since the yields of recoverable sugar, as indicated by purities in the 70s, would be at the level of marginal practicality, and these yields would be further decreased by the higher ash levels.
The type of curve illustrated in Fig. 1 indicated a peak before the frost, but the regression nature of the quadratic equation was influenced greatly by the data obtained after the Jan. and Feb. frosts.
A variety program should be based on testing clones of sugarcane in the area where they are to be grown; in the latitude of the Lower Rio Grande Valley, tolerance of cold is very important in the selection.
Varieties such as CP 57-614, CP 57-603, CP 65-357, L 60-14, and L 66-48, which appear to show some degree of tolerance to frost, should be evaluated thoroughly. On the other hand, varieties such as CP 55-30, L 65-69, L 64-67, and L 62-86 may not be suitable in Texas.
Irvine (4) has recommended caution in the use of juice free-acidities in gauging the extent of post- freeze damage to sugarcane because these acidity values vary in response to variety and environment. He suggested that measurement of the gum content of juices from freeze-damaged canes would provide a more reliable index of the extent of deterioration of the cane juice since this juice constituent has been found to increase in severely frozen canes (3). Gums were not measured in the studies reported here, and examination of the free-acidities reported in Table 3 indicated that these values do not provide a realible indication of the extent of juice deterioration which could occur after mild freezes. Where juice brix levels changed as greatly as those for L 65-69 and L 62-86, expression of free acidities as ml of alkali for titration of a specific volume of juice to pH 8.3 seems to be ineffective for detecting the degree of deterioration from frost. If the juice titers, as reported in Table 3, were calculated as aconitic acid and expressed as % on the brix solids of the juice, a significant change in acidities could be detected. Acidity % brix solids for L 65-69 prior to the Mar. harvest averaged 0.68%, and at the Mar.
harvest, 0.94%. Similar values on L 62-86 were 0.48% prior to Mar., and 0.70% at the Mar. harvest. No significant change in the L 64-67 juices were detectable by calculating acidities to the solids basis, doubtless because of the small change in juice solids content. This means of expressing juice acidities would provide a more satisfactory indicator of the sort of chemical changes noted in Table 3 following mild freezes than the customary use of titers, but it seems doubtful whether acidity measurements of either sort would accurately indicate the extent of gum formation following more severe freeze damage.
REFERENCES
1. Association of Official Agricultural Chemists. 1945. Official and Tentative Methods of Analysis.
Ed. 2, Washington, D. C. p. 559.
2. Fort, C. A., and McKaig, Nelson, Jr. 1939. Comparative chemical composition of juices of different varieties of Louisiana sugarcane. 11 S Department A Agriculture Tech. Bull. No. 688.
3. Irvine, J. E. 1967. Testing Sugarcane Varieties for cold tolerance in Louisiana. Proc. ISSCT 12:569-574.
4. Irvine, J. E. 1964. Variations in. pre-freeze juice acidity in sugarcane. Sugar Bull.'42:317-320.
5. Irvine, J. E. 1969. Duration of freezing: The effect on field cane. Sugar Bull. 48(1):10-12.
6. Irvine, J. E., and P. H. Dunckelman. 1971. New sugarcane clones with superior cold tolerance.
Proc. ASSCT 1 (NS): 115-117.
7. Irvine, J. E. 1971 Freeze resistance in varieties of mature sugarcane. Sugar Bull. 50:9-14.
8. Sund, K. A., and H. F. Clements. 1973. Croplogging sugarcane in saline soils of Iran. Res.
Bull. 162, Univ. of Hawaii Press. In press.