CHARACTERIZATION AND IMPROVEMENT OF SUGAR INDUSTRY PROCESS UNITS IMPACTED BY NEW PRODUCTION PRACTICES
Location: Commodity Utilization Research
Title: Impact of Subfreezing Temperatures on the 2006 Louisiana Sugarcane Harvest
| Legendre, B - LOUISIANA STATE UNIVERSIT |
| Tew, T. - SUGARCANE RESEARCH LAB |
| Birkett, H. - LOUISIANA STATE UNIVERSIT |
| Finger, C. - SUGARCANE RESEARCH LAB |
| Stein, J. - AUDUBON SUGAR INSTITUTE |
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 30, 2007
Publication Date: May 31, 2007
Citation: Legendre, B., Tew, T., Birkett, H., Eggleston, G., Finger, C., Stein, J. 2007. Impact of Subfreezing Temperatures on the 2006 Louisiana Sugarcane Harvest (abstract). Sugar Journal. 70(1):27-28.
The exposure of sugarcane to damaging frosts occurs in over 20 of the 79 sugarcane producing countries, but is most frequent on the mainland of the United States. This has forced the Louisiana industry to adapt to a short growing season (7-9 months) and a short milling season (about 3 months). The Louisiana sugarcane industry experienced an unprecedented series of subfreezing temperatures during the first week of December 2006. Absolute low temperatures across the sugarcane producing parishes during this period ranged from 20°F (-6.6°C) at the Dean Lee Research Station at Alexandria to 29°F (-1.7°C) at Houma (north to south) and from 24°F (-4.4°C) at Lake Charles to 27°F (-2.8°C) at Thibodaux (west to east). There was approximately 30-40% of the crop still to be processed at the time of the freeze events. The nature and extent of damage to sugarcane by subfreezing temperatures depends upon the intensity and duration of the freeze events. Temperatures between 32°F (0°C) and 28°F (-2.2°C) do little more than affect the terminal bud and tender leaves. Temperatures between 27°F (-2.8°C) and 26°F (-3.3°C) kill the growing point and the top third of the stalk. There is generally only a narrow band of green remaining in the leaves. A temperature between 25°F (-3.9°C) and 23°F (-5.0°C) kill most stalk tissue, lateral buds and leaves while temperatures below 22°F (-5.6°C) kill all stalk tissue and generally cause the stalk rind to split. Following freeze injury, dead tissue becomes vulnerable to the invasion of microbes, i.e., Leuconsostoc spp., Fusarium spp., etc., which often lead to deterioration of the juice and a reduction in the yield of recoverable sugar per ton of cane. The entry of these microbes is facilitated by dead lateral buds and by freeze cracks.
The impact of the subfreezing temperatures on commercial (LCP 85-384, HoCP 91-555, Ho 95-988, HoCP 96-540, L 97-128, L 99-226 and L 99-233) and candidate (HoCP 00-950 [officially released for commercial planting in Louisiana on April 26, 2007], TucCP 77-42 and CP 89-2143) varieties was measured at the USDA-ARS, SRRC Sugarcane Research Laboratory Ardoyne Farm, Houma, Louisiana. The concentration of polysaccharides, notably dextran, of the juice is one of the more sensitive criteria in determining the resistance of varieties to deterioration following freezing temperatures. Although it appeared that there were significant differences in total polysaccharides, with the candidate variety CP 89-2143 having the lowest concentration (4,264 ppm/Brix) and TucCP 77-42, the highest (7,085 ppm/Brix) at 6 weeks after the initial freeze event, December 5, there were no differences in dextran concentration among all varieties on the initial sampling date, December 11, 2006 and the last sampling date, January 19, 2007.
When all data were analyzed, including Brix and purity of juice, the yield of theoretical recoverable sugar per ton of cane, juice pH and titratable acidity, polysaccharide, dextran, and mannitol, three varieties appeared inferior in cold tolerance following the freeze events of early December at Houma. They were L 99-226, HoCP 00-950 and TucCP 77-42. Although it appeared that the subfreezing temperatures at the Houma site had minimal impact on yield of recoverable sugar per ton of cane for most commercial varieties, one must note that much of the state experienced temperatures considerably lower that undoubtedly caused considerably more deterioration and, consequently, a greater loss of recoverable sugar than found at Houma.
Most of the remaining cane in the field at the time of the freeze events was harvested, albeit, with a lower yield of recoverable sugar per ton of cane. Prior to the freeze, the average yield of recoverable sugar per ton of cane for the State for the week ending December 2, 2006 was at 212.5 lb/ton (106 kg/ton). However, for the week ending December 30, the average yield for the State was 168.5 lb/ton (84 kg/ton). Although it is postulated that the freeze events of early December had a significant impact on lowering the yield of recoverable sugar per ton of cane, another factor to consider was the considerable trash, to include field soil, in harvested cane following the freeze events, the result of wet field conditions caused by excessive rainfall.