COTVAR
is computer program that may be used to summarize cotton variety performance
data from state cotton variety tests conducted in five states (Arkansas,
Louisiana, Mississippi, Missouri, and Tennessee) in the Mississippi River
Delta region.Within each state
variety test, entries are evaluated at different sites and in different
experiments (also referred to as "tests") based upon maturity of
varieties (early or mid-maturity tests), years that the entry has been
evaluated (main or first-year tests), types of transgenic traits (e.g.
Roundup Ready Flex tests) or treatment of test (e.g. whether test is sprayed
with glyphosate).Specific varieties
entered in tests will typically differ among years (within a state), among
states (within a year), and among experiments within a state.Comparisons of data for different varieties
are only valid when the specific varieties are evaluated in the same
experiment.
Several terms throughout the program are linked to a glossary. Selecting one of these highlighted terms will create a popup screen which will display the definition of the term selected. The entire glossary of terms is also found at the bottom of this guide.
At different points throughout the program, additional information can be found on the output screens by allowing the mouse to hover over an item.
As the user makes choices, those choices will be displayed in a table at the top of the page during the course of the program.
The COTVAR program contains two program links at the top of the page.
The first item,
COTVAR Cotton Variety Selection, will return the user to the beginning of the program at any time to run a new COTVAR situation.
The second menu item, COTVAR User Guide, opens this document in a new screen. To return to the program, close the screen.
COTVAR Program Description
Step 1. Select the Year
Varietial differences in fiber quality are relatively consistent over
years. If fiber data are not available for most current year, user may be able obtain fiber data from pervious
year. If data from multiple years are desired, user may return to step 1 and choose alternate year.
The three most recent years will be available in COTVAR.
Only one year at a time may be selected.
Step 2. Select Variety Status
Users will be able to select from 3 categories of varieties: Commercially Available Varieties,
Experimental Lines, and Obsolete Varieties.
Experimental lines are often entered into variety tests before they
are commercially available. Sometimes these
new lines (along with standard varietal checks) are evaluated in
experiments (tests) separate from the main variety test. With rapid turnover of varieties, some varieties entered
in previous years may no longer be commercially available (i.e. obsolete).
Updates on variety status (e.g. an experimental line becomes an available or an available variety becomes obsolete)
and variety names (experimental to commercial name) will be made in COTVAR as
information becomes available.
Users can select one, two or all three selections for variety status.
Step 3. Select Variety Type(s)
Users will be able to select from 3 type of varieties: Multiple trait types (insect resistance and herbicide tolerance),
Single trait types (either insect resistance or herbicide tolerance), or Conventional type (no transgenic traits added).
Insect resistance traits include Bt, Bt2, and Widestrike. Herbicide tolerance traits include Round-up
Ready, Flex, and Liberty Link. If user wishes to compare varieties from different types, each appropriate type should
be chosen.
Users can select one, two or all three variety types.
Step 4. Select Location(s)
Users can quickly select from regions, or indiviual test sites can also be selected using these options:
All Sites, North Delta (includes MO, TN, northeast AR and northwest MS sites), South Delta (includes LA, central MS, southeast AR sites),
Hill Area (includes Mississippi sites), or Selected Test Sites - Ordered By State, then North to South within each State.
If selected test sites are chosen, a list of locations is displayed for Arkansas, Louisiana, Mississippi, Missouri, and Tennessee which have variety tests for the year selected.
Performance over several sites in previous years is a better predictor of the
relative performance of varieties at a specific site than relative performance
at that specific site in previous years. This is true because environment at one location varies greatly among
years. Varieties that perform well over a wide range of locations will likely also perform well over a wide range of
years. An exception may exist when comparing varieties that differ greatly in maturity since later maturing
varieties are not adapted to the northern Delta. Only varieties of similar maturity should
chosen if data from “all” locations or locations from different regions are to
be compared.
Step 5. Select up to five (5) varieties
Varieties will now be displayed for the year, variety status, variety type(s) and location(s) selected. The number of sites for each applicable experiment is shown for each variety.
Varieties are listed from the most frequently to least frequently tested. Columns to the right indicate the number
of test sites by experiment within each state. Valid comparisons can only be made among varieties evaluated in the same experiments. If varieties of interest
are not evaluated in the same tests, they can be compared independently to a
variety that is common to the diffferent tests.
User may select up to five varieties for comparison.
Step 6. Display Lint Yield Averages
Step 6 displays the mean lint yield and fiber quality for selected cotton varieties and experiments. Varieties selected are shown in the first column, and averages displayed are lint yield lb/a,
, Lint fraction %, Quality score, Fiber length in., Micronaire, Length Unif. %, and Fiber strength g/tex. The final row in the table displays the Total Number of experiments (at all sites selected). A link to a printer-friendly page is provided for this screen.
Step 7. Yields for Selected Varieties and Test Sites
Step 7 displays the yields (% of experiment means) for selected varieties and test sites and the data is sorted according to experiment mean. Information displayed includes location (city, state),
site code, soil type, irrigation status of the experiment, varieties selected, and experiment mean (lb/A).
A particular site may be listed more than once because of multiple experiments at that site. To see the experiment name, place the mouse over the line in the table and the experiment name will appear with addtional details about the location. A link to a printer-friendly page is provided for this screen.
Step 8. Display Additional Parameters
Additional information for selected varieties includes plant height (inches), percentage of open bolls, seed index, lint index, seed per acre, and leaf pubescence. The mean of the experiments for each of these parameters is shown, as well as the number of sites.
By placing the mouse over the data in the "Number of Sites" column, users can see the actual site numbers. A link to a printer-friendly page is provided for this screen.
For additional program information, contact:
Fred Bourland Director/Professor, Cotton Breeding
Becky Bridges Extension Computer Specialist
Northeast Research and Extension Center, P. O. Box 48
P.O. Box 391
Keiser, AR 72351
Little Rock, AR 72203
(870) 526-2199 fbourland@uaex.edu
(501) 671-2192 bbridges@uaex.edu
Special acknowledgement is given to Chalmers H. Davis, Jr., former Extension Computer Specialist, for initial program development.
University of Arkansas • Division of
Agriculture Cooperative Extension Service 2301 South University
Avenue Little Rock, Arkansas 72204 • USA Phone (501)
671-2000
