Submitted to: Sugar Journal
Publication Type: Trade Journal
Publication Acceptance Date: April 12, 2012
Publication Date: June 20, 2012
Citation: Chen, C.Y., Glaz, B.S., Del Blanco, I.A., Laborde, C., Vega, J., Davidson, R. 2012. Flowering Responses of Three Sugarcane Genotypes to Soil, Nitrogen Fertilizer Rate, and Shade. Sugar Journal. pp19.
Sugarcane (Saccharum spp.) breeders at Canal Point, FL select potential parental genotypes that range in flowering under natural conditions from none to sparse to prolific. Also, flowering among many genotypes needs to be synchronized in order to make designed crosses. The issue is emphasized by CP 89-2143, a highly desired parental genotype that does not flower most years. The objectives of this pot study were to examine the main effects and interactions of three levels of shade, three N fertilizer rates, and soil type (potting mix and sand soil) on flowering of three sugarcane genotypes. At Canal Point, CP 02-1143, CP 01-2390, and ‘CP 89-2143’ represent early, intermediate, and late/non flowering genotypes, respectively. In randomized complete block designs arranged as split plots in 2010 and 2011 with three replications, shade was the main plot with genotype x N rate x soil as the split plot in 2010 and 2011. An area under flowering progress curve (AUFPC) index was adapted to measure flowering progress each year. Highly significant differences were found for genotype in both years but N rate and soil type were significant only in 2011. The interaction of N x soil was significant both years while genotype x N x soil was detected only in 2010, and the interactions of genotype x N and soil x N were significant only in 2011. Results from t tests indicated that the greatest differences for mean AUFPC index among main effects were for genotype (ranging from 0.03 to 0.68), compared with 0.29 to 0.38, 0.31 to 0.38, and 0.34 to 0.36 for N, soil, and shade, respectively. These results indicate that at Canal Point, compared with these other treatments, genotype plays the major role in determining flowering time of sugarcane. Therefore, once breeders at Canal Point have prioritized parental genotypes, they need to manage photoperiod treatments, adjust N fertilization, optimize soil type, and extend the crossing season in order to raise the probability they will be able to make designed crosses. Further, breeders at Canal Point should cooperate with others at more southern latitudes to obtain flowers of remaining desired genotypes that still do not flower after all of the above treatment applications.