Potential for increasing sucrose content of sugarcane varieties in Louisiana through breeding
1995
Legendre, B.L. (U.S. Department of Agriculture, Louisiana (USA). Agricultural Research Service. Sugarcane Research Unit)
Improvements in sucrose content of sugarcane (Saccharum interspecific hybrids) grown in Louisiana, USA have been achieved through 5 cycles of recurrent selection beginning in the 1920s. Concurrently, sugar recoveries at the mills have increased dramatically and now exceed 100 kg per net ton of cane in a 7 to 9 month growing season. In the present study, the sucrose content of 39 commercial varieties used as parents in crosses of 5 successive cycles of recurrent selection was evaluated in plant and first-ratoon cane. Sucrose content increased 31 percent between Cycles I and V when averaged across plant and first-ratoon crops. The magnitude of this increase lessened with each successive cycles, particularly between Cycles IV and V (2 percent). The sucrose content of 100 or 150 candidate varieties from each of the 5 recurrent selection cycles was also determined. The average normal juice sucrose of candidate varieties from each recurrent selection cycle was significantly higher than the preceeding cycle through Cycle IV, increasing from 9.7 percent sucrose in the first cycle to 14.1 percent sucrose in the fourth cycle. The average sucrose content of the candidate varieties of the fifth cycle actually decreased to 13.6 percent (a drop of 3.5 percent from the preceeding cycle). These data indicate that further progress in improving the sucrose content of future varieties may be more difficult as sucrose content of parent varieties reaches an apparent plateau.
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