ESTABLISHING ACCEPTABLE LIMITS TO FLUE-CURED TOBACCO PERFORMANCE TRIALS

Crop performance trials are conducted in nearly every state as part of the land-grant mission. These trials have been conducted for flue-cured tobacco in the southeastern United States since 1954 and continue today. Even though the trials are conducted in a scientific manner, they are subject to variability caused by management and natural causes like diseases and insects. This article looks at the variability of 3 measurements from the North Carolina Official Flue-Cured Tobacco Variety Trials from 1981 through 2001. Yield, grade index, and dollar value per hectare ($/ha) were examined with the use of a procedure developed for other crops. First the relationship between error and mean was established. For these 3 traits there were no relationships between error and mean. A pooled (average) variance was calculated and then a maximum allowable variance was determined by multiplying the pooled variance by 2. Six out of 112 environments had questionable accuracy for yield; there were 7 questionable environmen...