The effect of genotype, environment and time of harvest on sugarcane yields in Florida, USA

Sugarcane (Saccharum spp.) is grown across different production environments and is harvested over a 5-month (mid-October-mid-March) period in Florida. While many studies have examined genotype x environment interactions and their implications for breeding program design, knowledge is limited regarding interactions of genotype, environment and time of harvest and their implications for growers. Three non-confounded data sets ('' case studies '') were analyzed to determine the effects of these three factors on kilograms of sugar per ton (KST), tons of cane per hectare (TCH) and tons of sugar per hectare (TSH) for recently released cultivars in south Florida. Cultivar (genotype), environment, time of harvest and their interactions had significant effects on KST, TCH and TSH. Sugarcane KST and TSH were reduced by 28 and 29%, respectively, when harvested in mid-October compared to optimum harvest dates in February. TSH varied from 2 to 46% across environments. The Lakeview '' warmland '' site near Lake Okeechobee recorded significantly higher TCH and TSH than other sites, and cultivars CP88-1508 and CP88-1834 recorded higher relative yields at Lakeview. Cultivar TSH varied up to 51% across the case studies. CP89-2143 had significantly higher KST than other cultivars in all 21 pairwise comparisons in the three case studies, and a remarkably high, stable KST ranking across environments. Growers in the Everglades Agricultural Area interested in improving sugarcane crop sucrose concentration should plant CP89-2143. However, significant genotype x environment interactions for other cultivars support continued multi-locational evaluation of sugarcane germplasm both during the breeding program and following cultivar release. (c) 2005 Elsevier B.V. All rights reserved.