Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2013
Publication Date: June 13, 2013
Citation: Edme, S.J. 2013. A historical perspective on cold tolerance in the Canal Point Sugarcane Breeding Program. American Society of Sugar Cane Technologists. pp 11. Technical Abstract: Developing sugarcane cultivars with greater freeze tolerance is an important objective of the USDA-ARS Canal Point breeding program, as temperatures around -3oC (27oF) cause serious sugar yield losses during the harvest season. To estimate if progress was made in freeze tolerance by breeding for cane and sucrose yields, a set of 58 historical sugarcane cultivars, released from 1920 to 2008, were planted on 27 Jan. 2011 at Hague, FL (lat:29o45’0”/long:82o25’48”) and exposed to subzero temperatures (TC). A non-replicated 5x15 augmented a-lattice design was adopted, with six replications of CP 89-2143 as a reference for freeze tolerance. The sucrose (commercially recoverable or CRS, in g kg-1) profile was monitored four times in the plant cane and first-ratoon crop-years, with the first samples taken before a freeze occurred in each year. The two-year dataset was analyzed in two steps, with variance components and adjusted cultivar means estimated first for individual sampling dates and later submitted in a combined analysis to assess the cultivar x environment interaction (CEI). Adjusted means were also regressed on years of release to obtain the gains in freeze tolerance due to breeding. Starting with the 2nd sampling, the cultivars were exposed to -2oC/28oF (6hrs), -7.7oC/18oF (4hrs), and -3oC (7hrs) in the plant cane, and to -1.5oC/29oF (7hrs), -3oC (8hrs), and to -1.5oC (8hrs) in the first-ratoon crop. The CEI effect was highly significant but not substantial, with the E and C effects contributing 45% and 17% more to the variation in CRS, respectively. Gains in CRS improved at a rate of 0.41 g kg-1 yr-1 (P<0.001) after exposure to TC =-3oC and at a rate of 0.46 g kg-1 yr-1 (P<0.001) to TC < -3oC. These results indicate that efforts to increase sucrose and cane yields in the CP program were accompanied with a significant improvement in adaptation to mild and harsh freeze conditions. The genetic component and its implications for further progress will be discussed.