The database used in this study comprised post-release cultivar evaluation trials established as part of the South African Sugarcane Research Institute’s (SASRIs) Variety Evaluation Project (VEP) from 1980 to 2014. In total, trial results from 150 trials, harvested over a combined 2650 crops (plant and ratoon crops) were used in the analysis.
Trials in the database consisted of six to thirteen cultivars each, planted in randomised complete block designs, with four to six replications per trial.
Experimental plots consisted of five or six rows (two outer guard rows not harvested) that were between eight to ten meters long and spaced 1 m (inland region) and 1.2 m (coastal region) apart. All trials were conducted under rainfed conditions and managed commercially by grower co-operators who were responsible for land preparation, fertilization, and weed control.Each trial was harvested for as many ratoon crops as the commercial field with in which it was established, and this ranged from a mini-mum of three crops (plant and two ratoons), to a maximum of ten crops. The intended HA of each trial, which was pre-determined in consultation with the grower co-operator, was based on the overall objectives of the trial, and was aligned to the prevailing commercial practice in the region. At each harvest, a series of traits of commercial relevance were determined for cultivar character and recommendation purposes.
Only the traits relevant to this study are described below.