Variety selection is one of the most important decisions a grower can make, as this decision determines the genetic yield potential for a particular field and environment. In 2013, the UGA OnFarm Cotton Variety Performance Evaluation Program demonstrated that improper variety selection could cost producers between $77 and $234 per acre!!! Therefore, this decision has a significant effect on growers’ profitability.
Variety selection can be complex, as consideration of many factors is necessary. Determining the most yield limiting factor in a particular farm or field may be the first step in this process. The most common yield limiting factor is usually water, although this was not very common in 2013. Other yield limiting factors that may influence variety performance include: nematodes, weed control, planting date, irrigation capacity, soil type, etc. Evaluation of variety stability (how frequently a variety performs at, or near, the top) is one of the best predictors for how well a variety may perform across a broad range of the factors listed above. Some varieties perform very well regardless of the environment or limiting factor. Other varieties may only be competitive in heavily irrigated conditions, and others may perform well in stressed situations. Therefore, it is important to also properly position of varieties into environments where they are likely to be competitive. Lastly, growers are encouraged to utilize data from as many years and environments as possible when making these decisions. Consideration to the general environmental conditions within a given year, may also provide insight on how varieties may perform in generally wet or dry years, as well as other general conditions that may be encountered across Georgia in a given year.
The results from the 2013 UGA OnFarm Cotton Variety Performance Evaluation Program are in, and this data is illustrated in the attached slides (see link below). The first slide illustrates the location of these trials and the range of geography captured in this program. In the second slide, varieties are ranked according to their average yield across all trials. Also listed is the percentage of trials in which a variety performed within the top 3, within the top 2, or was the number one variety in the trial. The third slide illustrates performance for individual environments. Environments are listed by number from left to right, based on their trial average. Lower yielding trials are listed on the left, and the higher yielding trials are shown further to the right. Varieties are ranked according to their combined average yield across all trials. Within each trial, the top variety is underlined and the top 3 varieties are highlighted in green font. This platform allows growers to see if varieties perform well across the board, or if some varieties may only perform well in certain types of environments. It is important to realize that the lower yield environments (trial averages) were not necessarily the result of drought stress in 2013, whereas in other years, this may be the case.
This and other production information will be discussed in detail during the winter county meetings. Your local county agent is an excellent resource when making variety decisions, and can help guide you through this process. The UGA Cotton Variety Performance Calculator (http://www.ugacotton.com/vault/cottoncalc/) is a useful tool for growers to evaluate variety performance across a number of environments, and it also allows the user to customize variety comparisions by location, trial type, year, and irrigated versus dryland. The calculator can be found on this website (www.ugacotton.com) under “Cotton Resources” (Cotton Variety Selection tab), or under “Decision Aids”. The calculator includes all of the onfarm trials as well as small-plot Official Variety Trial (OVT) data. OVT data can be found on this website as well, under “Cotton Resources” (Cotton Variety Selection tab).