1. Comparative Analysis of CWVI, Seedling Emergence and Vigor, and Crop Maturity in Cotton
Heath Stoerner

2. Introduction
Upland cotton (Gossypium hirsutum L.) has adapted very well to the Texas High Plains. Many of the requirements needed for cotton production are met.
However, a short growing season, usually 120 to 150 days, can sometimes cause limitations. The development rate of cotton is strongly influenced by temperature.
A cotton crop grows more slowly on cool days than on warm days. Low early season temperatures can drastically reduce seedling emergence and vigor.
A slower rate of emergence is frequently associated with low-vigor seed which will result in smaller plants (in comparison with high vigor seed)(Tekroney and Egli, 1990).
The high plains of Texas planted about 3.5 million acres in 2007.
Seed planted in early may or late april can put high levels of stress on the seed causing reduced stands.

3. Introduction
Results from a seed germination test performed in a seed germinator were compared to a field test, in which seedling vigor, plant maturity, fiber analysis, and yield data were taken.
Results from this study can be used to help producers better predict field performance using vigor tests.
Producers can use vigor tests to help decide on planting dates, planting rates and planting depths.
The producer will have a better idea of how the plant will respond to a early or late planting date.

4. Introduction
Cotton breeders can evaluate how a germplasm will perform in the field when seed quantity numbers are limited.
Vigor potential of a particular variety is initially established at the genetic level.
Seed companies can use vigor tests to evaluate various environmental conditions and the effect they have on resulting seed quality.
This is important for breeders because #2.
Has importance in all aspects from breeding and development of the seed to the production of a cotton plant within a farmers field.

5. Introduction
Gregory et al. (1986) showed good correlations between the cool-warm vigor index(CWVI) test and initial stand establishment.
Metzer (1987) reported results from the cool-warm vigor index(CWVI) test was a good indicator of final stand taken 6 weeks after planting.
In this study we hypothesized a relationship between the cool-warm vigor index(CWVI) and early season cotton maturity and vigor.

6. Cool-Warm Vigor Index
Seed vigor of each variety was obtained using the cool-warm vigor index test (CWVI).
The test was run using a Percival seed germinator.
50 seeds of each variety are rolled in moist germination towels and replicated 4 times.
This index is a combination of the standard warm germination test and the cool germination test which is also known as the Texas Cool Test.
For the warm germination test, seeds are held at 20°C for 16 hours and 30°C for 8 hours daily for 4 days.
This test is conducted under optimum conditions, and will only predict field emergence under optimum conditions.
The warm test is the only test required by law to appear on the label of every bag of cottonseed.

7. Cool-Warm Vigor Index
During the cool germination test, seeds are held at a constant 18°C for 7 days.
Seeds that have a combined root-hypocotyl length of 4 cm long are counted.
Numerical values from the warm germination test and the cool germination test are combined to give the cool-warm vigor index.
18 degrees Celsius or 64.4 degrees F is considered the breaking point for cotton seed degree decrease could cause numbers to fall considerably while 2-3 increase could cause results closer to those of the warm germination test. This test simulates early season planting when soil temperatures are cooler.
Average soil temperatures were 71.5 in 2006 and 68 degrees in 2007

8. Cool-Warm Vigor Index
Here what we are doing is measuring to see if the root-hypocotyl length is equal to or greater than 1.5 inches or 4 cm long

9. 24 Varieties Tested in 2006 DP117B2RF DP143B2RF DP164B2RF DP432R
FM9060F
FM9063B2RF
FM960B2R
FM960BR
FM960R
NG1553R
NG2448R
NG3273B2RF
NG3550RF
NG3969R
ST4357B2RF
ST4554B2RF
ST4575BR
ST4646B2R
ST4686R
ST5242BR
ST6565B2RF
STX0501RF
These varieties were used in both the CWVI test and the field test.
Seeds from the same seed lot were used for both test.
Varieties were chosen to give a wide range of CWVI values as well as differences in field performance.

10. 30 Varieties Tested in 2007 DP117B2RF DP143B2RF DP147RF DP164B2RF
DP445BGRR
FM9058F
FM9063B2RF
FM960B2R
MX0610B2RF
MX0613B2RF
MX0616B2RF
NG1553R
NG1572RF
NG2448R
NG3273B2RF
NG3550RF
NG3969RR
ST4357B2RF
ST4427B2RF
ST4554B2RF
ST5327B2RF
STX0626B2R
STX0627B2RF
STX0710B2RF
STX0711B2RF
STX0712B2RF
STX0721RF
STX0722RF
STX0723RF

11. Cool-Warm Vigor Index
Here are a few seeds that either failed to germinate or were not vigorous enough to count.

12. Cool-Warm Vigor Index
Gregory et al

13. Methods and Materials
160 plants were planted per plot using a randomized block design.
24 varieties using 3 replications at 2 locations was planted in 2006.
Texas Tech New Deal research farm had a May 11, 2006 planting date.
Texas Tech Quaker research farm had a May 13, 2006 planting date.
Average soil temperature for 2006 planting was 21.8 degrees

14. Methods and Materials
30 varieties using 3 replications at 1 location was planted in 2007.
Planted at the Texas Tech Quaker Research farm on May 17, 2007.
A sub-surface drip irrigation system was used and managed for maximum yield potential.
Average soil temperature for 2007 planting was 20 degrees.
Explain planter.

15. Methods and Materials
Plant emergence and vigor were determined by counting plants and categorizing into emerged, first, second, third, and fourth leaf stages.
A plant vigor index was established from this data.
This was performed 16 times from emergence until the fourth leaf stage in 2006 and 12 times in 2007.
The best looking stand from each planter row was determined and that row was used in all plots.

16. Methods and Materials
Here is another picture illustrating the differences in early cotton stages. Plant without the first true leaf and only cotyledons would be counted as emerged. The plant shown would be categorized at the first true leaf stage. When the second leaf were about the size of a quarter it would be at the second true leaf stage.

17. Methods and Materials August 7, 2006 Texas Tech New Deal Research Farm
Height differences were very noticeable. If you were to get out in the field you some stands thicker than others.
August 7, 2006 Texas Tech New Deal Research Farm

18. Methods and Materials
Yield differences are noticeable, you can pick out the four row plots.
October 27, 2006 Texas Tech New Deal Research Farm

19. Methods and Materials
Nodes above white flower as well as nodes above cracked boll were also recorded for crop maturity determination.
Yield data on each plot was taken with a mechanical harvester.
50 boll samples from each plot were ginned using a 10 saw gin and fiber quality analysis was performed by the International Textile Center.
NAWF and NACB are good indicators of mid and late season maturity.

20. Results Analysis was performed using a PROC MIXED procedure.
CWVI p-value = <.0001
NACB p-value = <.0001
P-values between leaf number by variety = <.0001
Micronaire p-value = .0301
This study was designed to show differences between varieties and we saw in the lab results as well as the field results.
HVI analysis showed differences as well

21. Results 2006 Graphs showing correlations between CWVI and plant vigor.
Two locations for the 2006 growing season. Both showed correlations between CWVI and early plant vigor. Not a real smooth regression line like we would like to see. I believe this is due to the poor seed viability we saw in 2006.
Graphs showing correlations between CWVI and plant vigor.

22. Results 2006
On the left we are comparing CWVI to Micronaire, micronaire is a fiber quality measurement of which fiber maturity is a component of. No relationship was found between the two.
On the right CWVI is compared to total bales per acre produced. Because of different variences throughout the growing season no correlation was found.

23. Results 2006 We saw some relationship Between NACB and CWVI.
NACB data was taken in late September.
This link was unexpected as

24. Results 2007
The 2007 data suggest a smoother slope with a higher correlation. This could be linked back to the higher viability of the seed used in 2007.

25. Results 2007
Again no correlation were found between CWVI and yield. In most cases correlation found between the two can be linked back to the effects of seed vigor on stand establishment.

26. Conclusions
The cool-warm vigor index test does show relationship to early season plant maturity and vigor.
This test can be used to predict how well a particular variety will perform early in the growing season.
Some relationship was found between late season maturity data (NACB) and cool-warm vigor index.
No correlation was found when the cool-warm vigor index test was compared to fiber maturity(micronaire) and yield data taken later in the growing season.
It could also help breeders to select for resistance to seed deterioration, in which higher vigor seeds should result.

27. Conclusions
Glat et al. (1982) noted that there have been many attempts to correlate seed vigor and yield and many have failed. Our data supports this as well.
This could be due to the cool-warm vigor test only being able to measure a limited number of factors, which may not be the same stresses that the seed may encounter during a growing season.
The closer the stress imposed during the vigor test is to actual stresses imposed in the field, the more accurate the test would be at predicting the performance of the seed.

28. References
Glat, D., B.B. Taylor, and M. D. Williams, The relationship of predictive tests for planting seed quality and field performance. Proc. Cotton Prod. Res. Conf. 1982:65-67.
Gregory, J., N. Hopper, and G Jividen Evaluation of several laboratory tests for determining cottonseed quality. Proc. Cotton Prod. Res. Conf. 1986:62-63.
Metzer, R. B Seed vigor index-field emergence relationships. Proc. Cotton Prod. Res. Conf. 1987:
Percival, A.E., J.F. Wendel, and J.M. Stewart Taxonomy and Germplasm Resources. in Cotton: Origin, History, Technology, and Production. W.C. Smith and J.T. Cothren eds. John Wiley and Sons, Inc., New York, NY.
Tekroney, D. M. and D. B. Egli, Relationship of seed vigor to crop yield: A Review. Crop Sci. 31: (1991)

29. Acknowledgements Dr. Craig Bednarz Cory Mills Even Maxwell Seth Sowder
Chris Griffin
Lu Feng
Daniel Olivier