Integration of Crop Production Strategies for Optimum Yield Potential

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
205	1510	1060	10%
205	1520	1060	10%
205	1540	1060	10%
205	1710	1060	50%
205	1820	1060	10%
203	1710	1020	10%

Progress 10/27/09 to 10/26/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Nothing to report -- PI deceased

Publications

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Nothing to report -- PI deceased.

Publications

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Commoodity groups and scientific researchers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The project has allowed training for 1 Ph.D. student to complete dissertation studies and 1 other student to continue training. Three M.S. candidates are also being trained under this project. How have the results been disseminated to communities of interest? Outputs-The second year of a three-year project investigating the impact of limb removal at specified stages of development was completed for its impact on cotton yield parameters. Additional studies were conducted on the use of an anti-ethylene compound to lessen the impact of temperature and water stress on the physiology and yield of cotton. The outcomes of these studies were presented in oral and poster sessions at the Agronomy and Physiology section of the Annual Beltwide Cotton Conferences, the Texas State Support meeting for cotton, and at departmental seminars. What do you plan to do during the next reporting period to accomplish the goals? Continuation of work on fruiting compensation by cotton from stress induced fruit loss and also from impacts of abiotic stresses will continue during 2014.

Impacts
What was accomplished under these goals? Outcomes and Impacts-A study was conducted at the Texas AgriLife Research Farm, near College Station, TX, to examine the effects and interactions of planting date, irrigation, and corn hybrid relative maturity. Treatments consisted of two irrigation strategies (rain-fed and 80% ET replacement), three planting dates (25-Feb, 10-Mar, and 25-Mar), and four hybrid relative maturities (117 day, 111 day, 95 day, and 83 day). In both years the study was a split-split plot design with four replications. The main plot was irrigation regime (rain-fed or 80% ET replacement), the sub-plot being planting date (Feb 25, Mar 11, Mar 25, referred to here after as 1, 2, and 3, respectively,), and sub-sub-plot being varieties with different relative maturities (RM). Hybrid relative maturity will be defined as days to mid-pollination. The varieties and RM were DKC67-21VT3Pro (~117 days), DKC61-35VT3Pro (~111 days), DKC45-51 GenSS (~95 days), and DKC33-53GenSS (~83 days), referred to here-after as 4, 3, 2, and 1, respectively. In general, all main effects were significant at the <0.001 probablility level. Interactions were not significant except for the irrigation and planting date. Irrigation had a significant positive effect on height compared to dryland corn. Higher soil moisture and cooler canopy temperatures may have contributed to this effect. Variety 4 (longest RM) was significantly taller than variety 1, 2, or 3. Planting date 3 (latest planting date) had significantly higher plant height than other planting dates tested. Irrigation combined with a later planting date resulted in significantly taller plants. Irrigation also had a significant positive effect on photosynthetic activity compared to dryland corn. The earliest planting date resulted in significantly lower photosynthetic activity compared to planting date 2 and 3. Varieties within different planting dates did not respond similarly. Analysis of florescence and canopy temperature (data not currently analyzed) may help explain this response. In general, all main effects were significant at the <0.001 probablility level for grain yield. The interactions were all significant at the <0.05 probablility level except for the irrigation, planting date, and variety interaction. Irrigationhad a significant positive effect on yield compared to dryland corn. Later maturing varieties (3 and 4) had significantly higher yields than varieties 1 and 2. Planting date 3 yielded significantly higher than other planting dates tested. Irrigation combined with delayed maturity resulted in significantly higher yields whereas irrigation combined with a later planting date also resulted in significantly higher yield. Within planting date, delaly of maturity increased yields; within variety except variety 4, delay of planting increased yield.

Publications

Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Chen, Y. and J.T. Cothren. 2013. Effect of 1-MCP on plant physiology and yield of cotton under abiotic stress. 67th Annual Cotton Agronomy and Physiology Conf. Poster presentation at Beltwide Cotton Conference, January 7-10, 2013. San Antonio, TX
Type: Theses/Dissertations Status: Submitted Year Published: 2013 Citation: Chen, Yuan 2013. Doctoral dissertation. Effect of 1-methylcyclopropene on cotton plants under abiotic stress. http://hdl.handle.net/1969.1/149615.
Type: Conference Papers and Presentations Status: Submitted Year Published: 2013 Citation: Crotwell, L.B., J.T. Cothren, and C.T. Lewis. 2013. Response of cotton to PGR treatment under differing drip irrigation regimes. 67th Annual Cotton Agronomy and Physiology Conf. Posters. Beltwide Cotton Conferences, January 7-10, 2013. San Antonio, TX
Type: Conference Papers and Presentations Status: Submitted Year Published: 2013 Citation: Maeda, M.M., J.T. Cothren, C.J. Fernandez, and C.T. Lewis. 2013. Means of identifying and reducing crop stress in cotton. Technical Conferences. 67th Annual Cotton Agronomy and Physiology Conf., Beltwide Cotton Conferences, January 7-10, 2013. San Antonio, TX
Type: Conference Papers and Presentations Status: Submitted Year Published: 2013 Citation: Moreno, J., J.T. Cothren, C.T. Lewis. Use of COTMAN to predict PGR application. 67th Annual Cotton Agronomy and Physiology Conf. Posters. Beltwide Cotton Conferences, January 7-10, 2013. San Antonio, TX

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: A 2-year project comparing the water use efficiency of corn genotype x planting date x irrigation was completed. An additional study in cotton utilizing planting density and irrigation was completed and is being analyzed for outcomes. Studies were also extended under fields, greenhouse, and laboratory conditions in an effort to optimize production outputs of cotton using an anti-ethylene induction growth regulator. These outcomes were presented in oral and poster sessions at the annual ASA Meetings, the Agronomy and Physiology section of the Annual Beltwide Cotton Conferences, the Texas State Support meeting for cotton, and the Texas Plant Protection Conference. PARTICIPANTS: J. T. Cothren, Texas AgriLife Research served as Principal Investigator (PI). Clay Lewis, Research Associate for the PI, was involved in all aspects of the project. Vladimir da Costa, Ross Rinderknecht, Alexis White, and Yuan Chen are directed by the PI during their graduate studies. Commercial companies which provided support in-kind and/or financial support through memorandum of agreements for specific aspects of the research included the following: Agro-Fresh Company, Monsanto Company, Bayer Crop Sciences, DuPont Crop Protection Stoneville Seed Company, and National Crop Insurance Services. TARGET AUDIENCES: Research efforts were targeted to provide management information to cotton producers through publications in peer reviewed journals, proceedings, and library citations in print and electronic format. the information was also presented in poster and oral format at local, regional, and national meetings composed of scientists from peer institutions, commodity producers, and agricultural industrial representatives. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Many environmental stress factors are known to impact cotton yield and quality. Ethylene production for example, is elicited under stress. This naturally occuring hormone is involved in the formation of the abscission layer and plays a major role in early season square and boll shed. The ethylene inhibiting compound 1-methylcyclopropene (1-MCP) has shown potential for protecting plants from certain stress-induced responses. It was examined in a 2-yr. field study for its ability to protect cotton plants against abiotic stress caused by ethephon, an ethylene promoter. A randomized complete block design with four replications was utilized for the study. Treatments consisted of two 1-MCP rates (0 and 10 g ai/ha) in combination with 4 ethephon rates (0, 2, 4, and 6 oz/A) that were imposed at first flower (FF) stage of development. Even in combination with 1-MCP, the 6 oz/A ethephon caused a significant decrease in quantum efficiency, membrane integrity, and lint yield. The ability to protect the plant against stress was shown at the 4 oz/A level of ethephon, suggesting that 1-MCP may perform better under moderate stress conditions. An additional field study focused on the impact of 1-MCP treatment of boll development and corresponding subtending leaves. Cotton boll weight was significantly increased by 1-MCP treatment at 30 days after flowering. This increase in boll weight was due to significant increases of both seed and lint weight. Other factors favorably altered by 1-MCP treatment included decreased membrane leakage and lipid peroxidation, as well as increased chlorophyll content in leaves that subtended the bolls. Research on the proper timing of defoliation treatment to optimize yield and quality of cotton was conducted on three varieties that are known to receive higher micronaire values. The purpose of the study was to keep imcronaire values in the premium range without sacrificing yield. The pre-determined percentages of the cultivars at which defoliant would be applied was 20%, 40%, 60%, and 80%. All varieties showed similar yields to the treatment; the 20% treatment yielded the lowest numerically, but the only statistical difference in yield occurred for the Stoneville (5458 B2RF) and Phytogen (565 WRF) varieties. None of the treatments or cultivars in this study gave micronaire values above the discount rate. For each variety, the optimum time for defoliation in this area of Texas under the particular environmental parameters present would be around 60 to 70% open bolls.

Publications

Chen, Y. and Cothren, J.T. 2012. Effects of 1-methylcyclopropene on boll development of cotton. Proc. 2012 Beltwide Cotton Conferences. Orlando, Florida. January, 2012. (Online proceedings).
Chen, Y. and Cothren, J.T. 2012. Effect of 1-methylcyclopropene on plant physiology and yield of cotton plants under abiotic stress cuased by ethephon. Abstracts of ASA, CSSA, and SSSA International Annual Meetings. October 2012. Cincinnati, Ohio.
Chen, Y. and Cothren, J.T. 2012. Effect of 1-MCP on cotton plants under ethephon stress. 2012 Proc. of Texas Plant Protection Conference. December 2012. College Station, TX.
daCosta, V.A. and J.T. Cothren. 2012. Cotton Flowering and Fruiting; Control and Modification with Plant Growth Regulators. pp. 79-108. IN Flowering and Fruiting in Cotton. Oosterhuis, D.M. and Cothren, J.T. (eds) 2012. Number Eight. The Cotton Foundation Reference Book Series. The Cotton Foundation, Cordova, TN.
Rinderknecht, R.A. and Cothren, J.T. 2012. Management of micronaire values by defoliation timing in three mid-fall season cultivars. 2012 Beltwide Cotton Conferences. Orlando. FL. January, 2012 (Online proceedings).

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Much of the field, greenhouse, and laboratory studies focused on means of environmental reducing stress and optimizing production inputs. The work with 1-MCP documented some potential for improving boll set and lint production in cotton, but consistency in performance remains a problem. Studies were initiated in comparing sub-surface drip irrigation and furrow irrigation in corn and cotton for impact on water use efficiency. PARTICIPANTS: J.T. Cothren, Texas AgriLife Research served as Principal Investigator (PI). Clay Lewis, Research Associate for the PI, was involved in all aspects of the project. Vlad da Costa, Yujin Wen, Ross Rinderknecht, Alexis White,and Yuan Chen are directed by the PI during their Ph.D. studies. Commercial companies which provided support in-kind and/or financial support through memorandum of agreements for specific aspects of the research included the following: Agro-Fresh Company, Monsanto Company, Bayer Crop Sciences, DuPont Crop Protection, and Stoneville Seed Company. TARGET AUDIENCES: Research efforts were targeted to provide management information to cotton producers through publications in peer reviewed journals, proceedings, and library citations in print and electronic format. The information was also presented in poster and oral format at local, regional, and national meetings composed of scientists from peer institutions, commodity producers, and agricultural industrial representatives. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Drought is known to impact cotton (Gossypium hirsutum L.) by affecting its physiological, morphological, and agronomic parameters. Ethylene, a growth hormone, can insure fruit abscission. The use of 1-methycyclopropene (1-MCP), an ethylene inhibitor, may minimize the loss of reproductive structures. A study was conducted to examine the effects of 1-MCP on gas exchange, plant growth/development, and yield components of cotton under drought during the reproductive phase. A 2-yr greenhouse project was conducted with two 1-MCP rates (0 and 2.4 g a.i. L-1)during a 14-h overnight incubation that were subjected to two water regimes (control and drought). Drought started to impact gas exchange at a moderate water stress, 5 DAT (days after 1-MCP treatment) (-1.4 MPa). The 1-MCP increased water use efficiency (WUE in well-watered plants at 1 DAT. Many of the yield components, plant mapping, and biomass parameters investigated were adversely affected by drought. However, drought increased specific leaf weight (SLW), chlorophyll (Chl) content, and harvest index. The 1-MCP improves reproductive node numbers mainly during drought, but did not lead to a better harvest index, since 1-MCP caused high fruit abscission. As such, 1-MCP did not ameliorate the detrimental effects of drought on gas exchange when water stress started to impact cotton plants. Additionally, 1-MCP had little or no positive effect on mapping, dry matter partitioning, and Chl content. A study was also conducted to determine the optimum defoliation timings for three mid-full season cotton varieties in the Brazos Valley region of Texas known to be at risk of receiving high micronaire values. Yield was also evaluated to determine the optimal defoliation timing to maximize profits along with non-discounted micronaire values. Percent open boll was used to verify defoliation timings. Four defoliation treatments were used in this study; 20%, 40%, 60%, and 80% open bolls. The three varieties used in this trial were, Phytogen 565 WRF, Delta Pine 1050 B2RF, and Stoneville 5458 B2RF. Yields for DP 1050 and STV 5458 were similar with PHY 565 being slightly lower. All three cultivars showed similar trends in yield across defoliation timings. Micronaire values remained in the premium range in all treatments for this year's data. Different micronaire trends for each variety were observed, the Phytogen and Delta Pine varieties showed a decrease in micronaire value from the 20% to 40% open boll treatments, while the micronaire values for the Stoneville variety increased. Based off of this year's data micronaire values did not reach the discounted range in any of the treatments; also yield was not significantly reduced unless it was defoliated before 40% open bolls for all treatments. Even though these varieties did not reach discounted micronaire levels, producers in the Brazos Valley region of Texas should still implement sound end of season management practices to maximize yield and improve fiber quality.

Publications

Chen, Y., D. Chen, and J. T. Cothren. 2011. Physiological effect of 1-methylcyclopropene on cotton plants by electrolytic leakage method. Abst. 2011 International Annual Meetings. ASA-CSSA-SSSA. October 16-19, San Antonio, TX
da Costa, V.A. and J. T. Cothren. 2011. Drought effects on gas exhange, chlorophyll, and plant growth of 1-methylcyclopropene treated cotton. Agron. J. 103:1230-1241.
Rinderknecht, R.A. and J. T. Cothren. 2011. Management of micronaire values in upland cotton by defoliation timing in three mid-full season cultivars. Proc. Beltwide Cotton Physiology Conferences. Jan. 4-7, Atlanta, GA.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: The results from the field and greenhouse studies revealed that 1-MCP impact was relatively short-lived from single applications of the compound. This was true for both foliar and gaseous treatments. The anticipated reduction in boll abscission was not evident, but there were other parameters that were positively affected. Under water stress, reproductive node count was improved. Our data indicated that ethylene production was not enhanced under the level of water stress examined. This finding should be examined further. PARTICIPANTS: J.T. Cothren, Texas AgriLife Research served as Principal Investigator (PI). John D. Rocconi, Research Associate for the PI, was involved in all aspects of the project. Vlad da Costa, Yujin Wen, Charles Camden, and Yuan Chen are directed by the PI during their Ph.D. studies. Commercial companies which provided support in-kind and/or financial support through memorandum of agreements for specific aspects of the research included the following: Agro-Fresh Company, Monsanto Company, Bayer Crop Sciences, DuPont Crop Protection, Arysta LifeScience, and Stoneville Seed Company. TARGET AUDIENCES: Research efforts were targeted to provide management information to cotton producers through publications in peer reviewed journals, proceedings, and library citations in print and electronic format. The information was also presented in poster and oral format at local, regional, and national meetings composed of scientists from peer institutions, commodity producers, and agricultural industrial representatives. PROJECT MODIFICATIONS: Project was revised in October 2009.

Impacts
Abiotic stresses impact cotton affecting physiological, molecular, morphological, and agronomic parameters and thus ultimately yield. One of the main yield components in cotton production is the number of bolls per unit area. However, boll abortion is increased when cotton experiences various stresses during its reproductive development that can consequently reduce lint yield. Prior to abscission, a burst in ethylene is observed which may be assumed to be the signal necessary to initiate abscission of that particular structure. Field and greenhouse experiments were conducted from 2007 to 2009 as a randomized complete block design with four replications in the field, and as a 2x2 factorial design in a split-block arrangement with five replications in the greenhouse. Field treatments consisted of three rates of 1-MCP (0, 25 and 50 g a.i. ha-1) in combination with a surfactant applied at mid-bloom. One day later, ethephon (synthetic ethylene) was applied as a source of abiotic stress. Greenhouse treatments were two 1-MCP rates (0 and 2.4 g a.i. L-1) during a14-h overnight incubation that were then subjected to two water regimes (control and stressed) as the source of stress. Greenhouse assessments with gas exchange analysis revealed that water deficit stress started to impact plants at a moderate water stress, 5 days after 1-MCP treatment (DAT) and a water potential (ψw) of -1.4 MPa. The 1-MCP increased water use efficiency in well-watered plants at 1 DAT. Many of the yield components, plant mapping, and biomass parameters investigated were detrimentally affected by drought. However, drought increased specific weight, chlorophyll content, and harvest index. The 1-MCP improved reproductive node numbers mainly during drought, but did not lead to a better harvest index, since 1-MCP caused high abscission. Ethylene synthesis and molecular investigations in greenhouse conditions showed that at 1, 5, 7, 9, 11, and 13 DAT, ethylene production of stressed plants never exceeded those of control plants. As the ψw became more negative ethylene production rate was reduced among stressed plants independent of 1-MCP treatments. However, at 1 DAT 1-MCP caused a transient climacteric stage (ethylene synthesis increase) in leaves. The two primary genes associated with ethylene synthesis, ACS6 aminocyclo-propane -1-carboxylic acid synthase) and ACO2 (1-aminocyclopropane-1-carboxylic acid oxidase) expression generally showed an identical trend that supported the ethylene synthesis data. The 1-MCP did not ameliorate any of the detrimental effects of water stress on gas exchange at the point where it started to impact cotton plants. 1-MCP had little or no positive effect on plant mapping, dry matter partitioning and chlorophyll content. Field investigations revealed that at harvest, fruit set in the upper portion of the canopy was influenced by 1-MCP. This portion of the canopy had a greater number of full size, yet immature bolls, which potentially could have had a positive influence on the lint yield. However, ethephon caused the highest lint yield since ethephon treated plants had more open bolls and total bolls in the lower canopy at harvest.

Publications

Carden, Charles W. 2010. Cotton response to 1-methylcyclopropene under different light regimes and growth states. Lint yield and yield components. M.S. Thesis. Texas A&M University. 128 pp.
Da Costa, V.A. 2010. Abiotic Stress EFfects on Physiological, Agronomic, and Molecular Parameters of 1-MCP Treated Cotton Plants. Ph.D. Dissertation. Texas A&M University.
Wen, Yujin, Giovanni Piccinni, J. Tom Cothren, Daniel I. Leskovar, Diane Rowland and Armen R. Kemanian. 2010. Regulated Deficit Irrigation Application and the Physiological Responses of Cotton (Gossypium hirsutum L.) in Southwest Texas. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Wen, Yujin, Giovanni Piccinni, J. Tom Cothren, Daniel I. Leskovar, Diane Rowland and Armen R. Kemanian. 2010. The Lint Yield and Fiber Quality of Cotton (Gossypium hirsutum L.) Under Several Regulated Deficit Irrigation Schemes in Southwest Texas. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Stanislav, Scott, Cristine L.S. Morgan, J. Alex Thomasson, Ruixiu Sui and J.T. Cothren. 2010. The Effect of Soil Specific Seeding Rates on Water Stress and Cotton Yield. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
White, Alexis D., J.T. Cothren, J.D. Rocconi and J.B. Bynum. 2010. The Effect of an Upper Limit Temperature Threshold on Heat Unit Calcula-tions, Defoliation Timing, Yield and Fiber Quality. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Minton, Whitney M., J.T. Cothren and J.D. Rocconi. 2010. Examining Effects of NAWF and Heat Units on Last Effective Boll Populations. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Carden, Charles W., J.T. Cothren and J.D. Rocconi. 2010. Impact of Light Intensity on Cotton Response to 1-Methylcyclopropene. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Currie, Jared M., J.T. Cothren, J.D. Rocconi. Fruiting Profiles of Cotton Treated with Various 1-Methylcyclopropene Formulations. 2010. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Da Costa, Vladimir A, J.T. Cothren and J.D. Rocconi. 2010. Abiotic Stress Impact on Reproductive Compnents of 1-MCP Treated Cotton Plants. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.
Rocconi, John D., J.T. Cothren. 2010. Use of Selected Fungicides to Elongate the Maturity of Mid-Season Upland Varieties. Proceedings of Beltwide Cotton Physiology Conferences. New Orleans, Louisiana. Jan 4-7.

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: The compound 1-methylcyclopropene (1-MCP) is an ethylene antagonist. It works by competing for the same active site as ethylene. Since ethylene enhances abscission of young cotton fruit, the inhibition of ethylene response could serve as a potential for yield increase. A two-year greenhouse study was completed on the investigation of 1-MCP under different water regimes on physiological parameters of cotton including plant mapping, biomass production, leaf growth, chlorophyll content, and ethylene emission. The study was conducted as a 2X2 factorial in a split-block arrangement with 5 replications. Treatments consisted of plants that were treated with a gaseous formulation of 1-MCP (1,000 ppb) or a zero level of 1-MCP in enclosures (tents) for 14 hours overnight. Two water regimes (well-watered and water stressed) were utilized. Treatments were initiated when plants reached the 16-node stage of growth. All plants were well-water until the time of the 1-MCP gassing. At that time, water was withheld until the water content of fritted clay in which the plants were grown reached 80% of the water holding capacity of a measured volume of the growth media contained in 3-gallon containers. This occurred at approximately 7 days following cessation of watering. Then, watering was resumed to keep water level at the 80% designation in the stressed treatments. Statistical analyses consisted of ProcMixed (SAS 8.2) with Fisher's protected LSD (P≤0.05). Results at 23 days after gaseous 1-MCP treatment showed that relative to the untreated control, 1-MCP increased abscission of fruit, but increased square number, and reproductive nodes while decreasing number of vegetative nodes. An interaction was observed for fruit at the second position fruiting sites by increasing the number of fruit when well-watered plants were treated with 1-MCP. In addition, 1-MCP increased leaf area, leaf weight, vegetative weight (petioles and stems), and reproductive weight (squares, flowers, bolls). Tagging of leaves showed increases in leaf growth, more so in the water-stressed treatment with 1-MCP treatment, although the well-watered treatment also showed positive responses to 1-MCP treatment. Responses of ethylene emission were mixed. Under water stress, 1-MCP increased ethylene production for up to 7 days after treatment then decreased until measurements ceased at 14 days. Under well watered conditions, 1-MCP showed lower ethylene emissions up to the 7th day after which it decreased. No significant differences were found for chlorophyll levels during the study period. A second study was completed under field conditions to examine the ability of 1-MCP to counter shading effects. Shade cloth was used to reduce light intensity by 63% to plots that had been treated one day earlier with a foliar application of 1-MCP applied at four different stages of crop development (pinhead square, first flower, peak flowering, and during boll development). Shade imposed during peak flowering and boll development reduced lint yield significantly compared to the other treatments. The use of 1-MCP at the boll development stage increased lint yield by 16% compared to the untreated control. PARTICIPANTS: J.T. Cothren, Texas AgriLife Research served as principal investigator (PI). John D. Rocconi, Research Associate for the P.I., was involved in all aspects of the research project. Vlad da Costa and Yujin Wen are directed by the P.I. during their Ph.D. studies. Commercial companies which provided support in-kind and/or financial support through memorandum of agreements for specific aspects of the research included the following: Agro Fresh Company, Monsanto Company, Bayer Crop Sciences, DuPont Crop Protection, Arysta LifeScience, and Stoneville Seed Company. TARGET AUDIENCES: Research efforts were targeted to provide management information to cotton producers through publications in peer reviewed journals, proceedings, and library citations in print and electronic format. The information was also presented in poster and oral format at local, regional, and national meetings composed of scientists from peer institutions, commodity producers, and agricultural industrial representatives. PROJECT MODIFICATIONS: Project was revised for five additional years that began in October 2009.

Impacts
The use of 1-MCP presents a useful mechanism for examining stress responses and ethylene production in crop plants. It appears that 1-MCP may have the potential to counter detrimental responses encountered at specific stages of crop development in cotton (boll filling), such as that which occurs during prolonged shading periods. Likewise, positive responses were shown for overcoming stresses associated with water limitation where several parameters (leaf area, leaf weight, and leaf expansion) were several parameters were increased relative to the untreated control.

Publications

da Costa, Vladimir and J.Tom Cothren. 2009. Stress remediation with an anti-ethylene compound in cotton. ASA Abstracts. November 1-5, Pittsburgh, Pennsylvania. 292-11.
da Costa, Vladimir, and J. Tom Cothren. 2009. Drought effects on physiological traits of 1-MCP-treated cotton plants. Proc. Beltwide Cotton Conferences, Poster Session, San Antonio, Texas. January 5-8.
Fromme, Dan D., J. Tom Cothren, and Carlos J. Fernandez. 2009. Identification of the last effective boll population for basing end of season management decisions. Proc. Beltwide Cotton Conferences, San Antonio, Texas. January 5-8.
Wen, Yujin. 2009. Regulated deficit irrigation application and the physiological responses of cotton in Southwest Texas. ASA Abstracts. November 1-5, Pittsburgh, Pennsylvania. 65-6.
Carden, Charles W. and J. Tom Cothren. 2009. Cotton response to 1-Methylcyclopropene under different light regimes and growth stages. Proc. Beltwide Cotton Conferences, Poster Session, San Antonio, Texas. January 5-8.
da Costa, Vladimir and J.Tom Cothren. 2009. Drought effects on physiological traits of 1-MCP treated cotton plants. ASA Abstracts. November 1-5, Pittsburgh, Pennsylvania. 65-10.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Maintaining profitable and sustainable production of cotton (Gossypium hirsutum) relies on improvements in management. Premature harvest aid application can result in reduced profit to the grower through the need for additional applications, reduced lint yield, poor fiber quality, and/or delayed harvest. A two-year study was completed to determine the proper defoliation timing to optimize lint yield and fiber quality through calculating heat unit (HU) accumulation beyond cutout, defined as five nodes above white flower (NAWF=5). Treatments were applied as a split-plot arrangement using a randomized complete block design with four replications. Treatments were applied at either of three nodal positions (NAWF=5, 4, or 3) beginning at 361 HU and continuing at 417, 472, 528, and 583 HU beyond for each other corresponding nodal position. Just prior to defoliation, 10 plants per plot were evaluated for percent open boll (POB) and nodes above cracked boll (NACB). Lint yield was negatively impacted in South Central Texas when defoliation was initiated at 472 HUs beyond NAWF=5. Defoliation at 60 POB resulted in as much as 29% more lint yield than defoliation based on the current benchmark of NAWF=5 plus 472 HUs. Our finding suggests NAWF=5 is neither an indicator of the last effective flower population in all production locations, nor a proper guide for timing cutout on which end-of-season management decisions should be based in South Central Texas. Additional work in a multi-location study on the last effective boll population of ultranarrow row (UNRC) and conventional row cotton (CONC), (25 cm or less compared to 96 to 102 cm spacing, respectively) indicated that the UNRC produced the majority of seedcotton on NAWF 3 to 5, while CONC produced the most seedcotton on NAWF 4 to 6. A similar pattern was shown for boll numbers. This study also demonstrated that physiological cutout occurred at NAWF<5 in both UNRC and CONC. PARTICIPANTS: J.T. Cothren, Texas AgriLife Research served as principal investigator (PI). J.B. Bynum, Research Associate for the P.I., was involved in all aspects of the research project. Daniel D. Fromme, Vladimir da Costa, Thomas Moeller, and Charles Carden were or are being directed by the P.I. during their graduate studies. Texas State Support Committee for Cotton provided financial support. Commercial companies which provided support in-kind and/or financial support through memorandum of agreements for specific aspects of the research included the following: AgroFresh Company, Monsanto Company, Bayer Crop Sciences, DuPont Crop Protection, MicroFlo Company, Arysta LifeScience, and Stoneville Seed Company. TARGET AUDIENCES: Research efforts were targeted to provide management information to cotton producers through publications in peer reviewed journals, proceedings, and library citations in print and electronic format. The information was also presented in poster and oral format at local, regional, and national meetings composed of scientists from peer institutions, commodity producers, and agricultural industrial representatives. PROJECT MODIFICATIONS: None Reported

Impacts
Results of the two studies conducted failed to support the current benchmark of using the NAWF=5 plus 472 HU as the proper time for harvest aid application. Both studies indicated that harvest aid timing needs to be fine-tuned for the specific area of the Cotton Belt in which the crop is grown. Efforts to improve on this benchmark are continuing with the use of different upper temperature thresholds to calculate heat unit accumulation.

Publications

Viator, R.P., C.O. Gwarthmey, J.T. Cothren, J.T. Reed, E.D. Vories, R.C. Nuti, K.L. Edminsten, and R. Wells. 2008. Influence of ultranarrow row and conventional cotton on the last effective boll population. Agron. J. 100: 1327-1331
Bynum, Josh B. and J.T. Cothren, 2008. Indicators of last effective boll population and harvest aid timing in cotton. Agron. J. 100: 1106-1111
Clawson, E.L., J.T. Cothren, D.C. Blouin, and J.L. Satterwhite. 2008. Timing of maturity in ultra-narrow and conventional row cotton as affected by nitrogen fertilizer rate. Agron. J. 100: 421-431
Carden, C., J.B. Bynum, and J.T. Cothren. 2008. Evaluation of leaf tissue nutrient status after glyphosate application to cotton. Proc. Beltwide Cotton Conf., Nashville, TN; Jan 8-11
daCosta, V., J.B. Bynum, and J.T. Cothren. 2008. Effects of 1-MCP on late season cotton fruit set. Proc. Beltwide Cotton Conf., Nashville, TN; Jan 8-11.
Moeller, T.S., J.B. Bynum and J. T. Cothren. 2008. Influence of differing heat unit calculations on fiber quantity and quality. Proc. Beltwide Cotton Conf., Nashville, TN; Jan 8-11
Bynum, J.B., and J.T. Cothren. Physiological application for diagnosing cotton water use efficiency. 2008 Proc Beltwide Cotton Conf., Nashville, TN; Jan 8-11
Fromme, Dan., J.B. Bynum, and J.T. Cothren. 2008. Effects of an upper limit threshold on heat unit calculation and defoliation timing. Proc. Beltwide Cotton Conf., Nashville, TN; Jan 8-11.

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: The ability to determine the most profitable time to defoliate cotton (Gossypium hirsutum L.) is key to managing a cotton crop. Delaying defoliation exposes open bolls to a higher probability of rainfall, which reduces lint yield and fiber quality. Conversely, premature defoliation had detrimental affects on lint yield and fiber quality. Recent efforts to fine-tune defoliation timing have focused on the use of heat-unit (HU or DD15) accumulation after physiological cutout or five nodes above white flower (NAWF=5). Due to inconsistent results across a wide range of field environments when utilizing HU accumulation past cutout, the adoption of this method has been limited. This may be reflective of maximum day time temperatures during the growing season in many regions of the Cotton Belt that are above optimum for cotton growth and development. This research focuses on efforts to identify an upper temperature threshold (UTT) for calculating degree days for defoliation timing. Field studies were conducted for three consecutive growing seasons in the Brazos River Valley and Upper Gulf Coast regions of Texas using three upper temperature thresholds (32 C, 35 C, and no upper temperature limit) in combination with five HU timings above cutout (361, 417, 472, 528 and 583) to determine proper defoliation timing. Other management strategies for improving cotton production included the investigation of I-methylcylopropene (1-MCP) to counter stress ethylene and promote fruit set and maturation for yield increases. Additional efforts were also placed on identifying physiological techniques to identify stress and select for cultivars exhibiting greater tolerance to water stress. PARTICIPANTS: J.T. Cothren, Texas AgriLife Research served as principal investigator (PI). J.B. Bynum, Research Associate for the P.I., was involved in all aspects of the research project. Daniel D. Fromme and Justin J. Scheiner were directed by the P.I. during their Ph.D. and M.S. studies, respectively. Texas State Support Committee for Cotton provided financial support. Commercial companies which provided support in-kind and/or financial support through memorandum of agreements for specific aspects of the research included the following: AgroFresh Company, Monsanto Company, Bayer Crop Sciences, DuPont Crop Protection, MicroFlo Company, Arysta LifeScience, and Stoneville Seed Company. TARGET AUDIENCES: Research efforts were targeted to provide management information to cotton producers through publications in peer reviewed journals, proceedings, and library citations in print and electronic format. The information was also presented in poster and oral format at local, regional, and national meetings composed of scientists from peer institutions, commodity producers, and agricultural industrial representatives. PROJECT MODIFICATIONS: None Reported

Impacts
Utilizing an UTT to calculate daily HU with the temperatures investigated failed to explain differences in the optimum time to defoliate based on accumulated HU from cutout. Accumu lated HU, however, had a significant impact on defoliation timing. Maximum lint yields at the two locations differed for amount of HU collected from cutout suggesting that the upper limit may be specific for location and/or impacted by other environmental parameters such as solar radiation accumulation. Data also suggested that a lower upper temperature threshold may have utility. Studies with 1-MCP indicated a potential for lint yield increases, but this increase was not reflected in yield parameters. Preliminary results indicated a lack of correlation between increased level of water stress and photosynthetic activity measured as fluorescence.

Publications

Bynum, J.B., J.T. Cothren, R.G. Lemon, D.D. Fromme, and R.K. Boman. 2007. Field evaluation of nitrophenolate plant growth regulator (Chaperone) for the effect on cotton lint yield. J. Cot. Sci. 11:20-25.
Fromme, Daniel D. 2007. Effect of an upper temperature threshold on heat unit calculations, defoliation timing, lint yield and fiber quality in cotton. Ph.D. Dissertation. Texas A&M University. 75 pp.
Scheiner, Justin J. 2007. Effect of 1-methylcyclopene on upland cotton. M.S. Thesis. Texas A&M University. 80 pp.
Horak, M. J., E.W. Rosenbaum, C.L. Woodrum, A.B. Martens, R.F. Mery, J.T. Cothren, J.A. Burns, J.E, Nickson, T.A. Paster, C. Jiang, J.L. Hart, and B.B. Sammons. 2007. Characterization of Roundup Ready Flex Cotton, "MON 3539", for use in ecological risk assessment: Evaluation of speed germination, vegetative and reproductive growth, and ecological interaction. Crop Sci. 47: 268-277.
Falkenburg, N.R., G.R. Piccinni, J.T. Cothren, D.L. Leskovar, and C.M. Rush. 2007. Remote sensing of biotic and abiotic stress for irrigation management of cotton. J. Agric. Water Management. 87: 23-31.
Scheiner, J.J., J. Bynum, and J.T. Cothren. 2007. Examining the effects of 1-methylcyclopropene on cotton lint yield. Proc. Beltwide Cotton Conf., New Orleans, LA. Jan 9-12. p 1277-1279.
Bynum, J.B., J. Scheiner, and J.T. Cothren. 2007. Physiological techniques for determination of drought tolerance in cotton cultivars. Proc. Beltwide Cotton Conf., New Orleans, LA. Jan 9-12. p. 519.
Silvertooth, J.C., J.T. Cothren, and C.W. Bednarz. 2007. The physiological basis of nitrogen demand. Proc. Beltwide Cotton Conf., New Orleans, LA. Jan 9-12. pp. 1284-1289.

Progress 01/01/06 to 12/31/06

Outputs
Due to declining cotton prices and higher input cost, it is imperative that growers reduce production costs to maintain profitability. Chemical inputs, such as harvest aids, encompass a major portion of the production costs and can easily exceed $30 per acre. Therefore the ability to reduce harvest aid inputs could potentially offer increases in profitability. A three-year field study was conducted at the Texas Agricultural Experiment Station in Burleson County, Texas. A randomized complete block design with four replications was used for the study. Application of treatments occurred when the plots were at 60 percent open boll and harvest was made by machine picking 14 days after treatment (DAT). Harvest aid treatments consisted of a standard recommended rate of the harvest aid and a corresponding reduced rate, that usually was equal to one-half the recommended rate. Parameters examined included an evaluation of percent defoliation, desiccation, and overall performance at 7 and 14 DAT. Regrowth was also assessed at 21 DAT. Lint quality characteristics were determined by subjecting fiber samples to high volume instrument analysis. Economic value of the lint was assessed using the most current Commodity Credit Corporation characteristics and schedule of premiums and discounts. Statistical analyses was performed using PROC MIXED in SAS V.9.1.3 over years and means were separated using Tukeys at the 95 percent, significance level. No significant difference between harvest aid treatments were present for lint yield. Reducing the rates of harvest aids applied did not negatively impact lint yield. No significant differences were detected among reduced rates and their corresponding higher rates for overall performance rating at 14 DAT. All treatments resulted in an overall performance rating higher than the benchmark of 80 for satisfactory performance. Neither loan value nor lint value was impacted by treatment effects. Reduced rate defoliants did not negatively affect lint yield, overall performance rating, loan value, or lint value compared to their corresponding higher rates.

Impacts
Declining cotton prices combined with higher input costs requires that various strategies be examined to maintain profitability. Since end of year crop termination can exceed $30 per acre, any reduction in these costs could lead to higher returns. Studies were conducted to compare reduced rates of defoliants compared to recommended standards. Reductions in rates up to 50% of those recommended for defoliation failed to show differences in lint yield, fiber quality, loan value, and lint value when compared to the standard recommendation. The results of this three-year study suggest that reducing the rates of defoliants applied could potentially result in higher returns to cotton producer.

Publications

Clawson, E.L., J.T. Cothren, and D.C. Blouin. 2006. Nitrogen fertilization and yield of cotton in ultra-narrow and conventional row spacings. Agron. J. 98:72-79.
Falkenberg, N.R., G.R. Piccini, J.T. Cothren, D.L. Leskovar, and C.M. Rush. 2006. Remote sensing of biotic and abiotic stress for irrigation management of cotton. J. Agri. Water Management. 87:23-31
Bynum, J.B., and T. Cothren. 2006. Field evaluations of Roundup Ready Flex Cotton. In: Debbie Richter (ed.) Proc. Beltwide Cotton Conf. National Cotton Council. Memphis, TN. 3-6 Jan. San Antonio, TX.
Fromme, D.D., R.G. Lemon, J.T. Cothren, J.B. Bynum, and J. Pigg. 2006. Evaluation of Mepex Gin Out application at cutout. In: Debbie Richter (ed.) Proc. Beltwide Cotton Conf. National Cotton Council. Memphis, TN. 3-6 Jan. San Antonio, TX.
Scheiner, J.J., J.B. Bynum, and J.T. Cothren. 2006. Evaluating the performance of reduced rate and standard rate harvest aids for Central Texas. In: Debbie Richter (ed.) Proc. Beltwide Cotton Conf. National Cotton Council. Memphis, TN. 3-6 Jan. San Antonio, TX.

Progress 01/01/05 to 12/31/05

Outputs
Two field studies were conducted over two years at the Texas A&M Agricultural Experiment Station in Burleson County, TX. The main objective of the study was to examine the physiological effects of repeated foliar treatments of imidacloprid (trade name Trimax) and a foliar formulation of thiomethoxam (trade name Centric 40 WG) on early, mid, and late season plant growth, chlorophyll content, nitrogen content, yield, and fiber quality of cotton. A second objective was to determine the correlations between data derived from a Minolta SPAD meter, total nitrogen content, and chlorophyll content of cotton. The study was conducted under irrigated conditions in an experimental design that consisted of four replications within a randomized complete block. Trimax and Centric 40 WG were applied alone at either one, two, and three applications, in addition to an untreated control. Timings of these applications occurred at the 10-leaf stage, 10-leaf stage plus 10 days after initial treatment (DAIT), and 10-leaf stage plus 10 DAIT plus 20 DAIT. Like applications and timings of Centric 40 WG to those of Trimax were made at a labeled rate of 1.33 oz/A. Data was observed and recorded for plant height, total nodes. SPAD readings (as a reference for chlorophyll content), chlorophyll analysis, nitrogen analysis, mid-season plant mapping and biomass partitioning, end of season box mapping, and yield and fiber quality analysis. Lint yield failed to show significant differences between treatments. Percent nitrogen and SPAD values were highly correlated (P< 0.001). However, no correlation was found for chlorophyll levels in relation to nitrogen content or SPAD values. The two-year field study with repeated applications of Trimax revealed no statistically significant increase in crop response, overall physiological activity, or crop growth rate compared to the untreated control. In other another two-year field study, experiments were conducted to assess the effects of plant density on lint yield and fiber quality. This study was initiated due to the increased cost of planting transgenic or stacked gene cotton varieties. Experimental design was a split-plot design with four replications of three cultivars (SG 215 BG/RR, DP 555 BG/RR, and ST 4892 BG/RR) in high, ideal, and low densities that ranged from 74 to 222 thousand plants per hectare. Lint yield was unaffected by plant density in 2003 or 2004. However, low plant density treatments contained significantly more bolls per plant as a result of the plants compensatory nature to produce the same number of bolls in a given area. These low density treatments also produced more vegetative biomass per plant. Due to lower boll number and lower ginout percentage, ST 4892 produced the lowest lint yield each year. Lint quality was unaffected by density or cultivar treatments in either year.

Impacts
Two commonly used insecticides, Trimax and Centric 40 WG, were examined for growth regulating properties in cotton. At the rates and times of applications investigated, no significant differences were present between the insecticide treatments and the untreated plant, for parameters that were monitored for growth responses or physiological activity. The study for affect of plant density on yield of cotton showed no differences in yield in a range of low to high planting densities due to cottons ability to compensate in fruit production at lower densities.

Publications

Falkenberg, N.R., Piccinni, G., and Leskovar D.I. 2005. Remote sensing for site-specific management of biotic and abiotic stress in cotton. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.
Bynum, J.B. 2005. Nodes above white flower and heat units as indicators of cotton harvest and timing. M.S. Thesis. pp. 65.
Halfmann, S.W. 2005. Planting density affects on lint yield and quality of three stacked-gene cotton cultivars. M.S. Thesis. pp. 85.
Gola, T.A., Cothren, J.T., and Bynum, J.B. 2005. Strategies for Chaperone and Pentia use on cotton. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.
McGuire, C.C. 2005. Evaluation of PGR properties of Trimax on cotton. M.S. Thesis. pp. 74.
Stabile, M. 2005. Site-specific strategies for cotton management. M.S. Thesis. pp. 113.
Fromme, D.D., Cothren, J.T., and Bynum, J.B. 2005. The effect of an upper limit temperature threshold on heat unit calculations, defoliation timing, yield, and fiber quality. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.
Halfmann, S.W., Cothren, J.T., and Bynum, J.B. 2005. Plant density effects on yield, lint quality, and last effective boll populations in cotton. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.
Niccum, B.M., Cothren, J.T., and Bynum, J.B. 2005. Fruiting and yield responses in cotton to insecticidal treatment. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.
McGuire, C.C., Cothren, J.T., and Bynum, J.B. 2005. Evaluation of PGR properties of Trimax in cotton. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.
Bynum, J.B., and Cothren, J.T. 2005. Optimizing harvest-aid timing, yield, and quality by monitoring nodes above white flower and heat unit accumulation. Proc. Beltwide Cotton Conf., January 4-7, New Orleans, LA. CD-ROM.

Progress 01/01/04 to 12/31/04

Outputs
Previous studies on cotton have shown that some insecticides possess plant growth regulator properties. Imidacloprid, tradename Trimax (TRI), is an insecticide that has been reported to enhance early plant growth and possibly increase yield. A series of studies were completed under field and greenhouse conditions to examine the physiological effects of TRI treatments on plant growth, yield, and fiber quality of cotton. A split-plot design included seed treatments as the whole plots and foliar TRI applications (0.11 L TRI ha-1) as the sub-plots. Seed treatments included an untreated control (UTC), Temik(aldicarb)(TEM), Crusier(thiamethoxam)(CRU), and Gaucho(imidacloprid)(GAU). Foliar treatments included O applications of TRI (UTC), 1 application applied at the 5-leaf stage (1 app), 2 applications applied at 5-leaf stage and 10 days after initial treatment (DAIT) (2 app), and 3 applications applied at 5-leaf stage, 10 DAIT and 20 DAIT (3 app). Chlorophyll determinations failed to show differences in chlorophyll content among TRI applications from SPAD readings. Vigor was better in seed treatments as taller plants were observed early season compared to seed that were not treated. Lint yield was not affected by seed treatments. Numerical increases in yield were observed in all TRI foliar treatments compared to the control, which was also reflected in box-mapping data. This numerical increase was also present for mean boll weights at fruiting positions one, two, and three. Glasshouse studies for relative growth rate also failed to show differences in leaf area production, total weight, or partitioning coefficients between treated and untreated plants. The data from these studies did not support the hypothesis that TRI enhanced cotton growth and development. An additional study was completed examining selected growth characteristics, yield, and fiber quality of genetically modified and conventional cotton as affected by organophosphate insecticides and foliar phosphorus application. This study was conducted because of reports of variable results in fiber quality and yield in these cultivars and the potential for yield reduction occurring from reduced use of broad-spectrum insecticides, such as organophosphates. A four replication strip-plot experimental design was utilized with cultivar serving as whole plot and insecticide regime as the sub-plot. Three cultivars of the same recurrent parent (ST 4892 BR, ST4793R, and ST474) were planted over a 2-year study. The insecticide regime consisted of a non-phosphate (NP) insecticide regime, a NP + foliar phosphorus (FP) treatment, and an OP treatment. The study showed conclusive positive yield differences between cultivars with ST4892 BR yielding the most lint, but insufficient evidence was generated to conclude that OP insecticides influence growth, yield, or fiber quality characteristics of the cultivars examined.

Impacts
These studies document that insecticidal seed treatments increased the vigor of cotton plants above that of the untreated seed (control). However, results from this 2-year study failed to document physiological response to foliar applications of the insecticide imidacloprid.

Publications

Hundley, C.A. 2004. Evaluation of organophosphate insecticides on performance of transgenic and conventional cotton. M.S. Thesis. Texas A&M University. 187. pp.
Boman, R.K., T.A. Baughman, C.R. Stichler, S.D. Livingston, B.E. Warrick, D.D. Fromme, G.C. Moore, D.J. Pigg, J.R. Stapper, J.T. Cothren, J.B. Bynum, and R.G. Lemon. 2004. Effects of Chaperoner on Texas Cotton. Texas Plant Protection Conf. December 8-9.
Bynum, J.B. and J.T. Cothren. 2004. The evaluation of the rainfastness of harvest aid formulations of Dropp. Texas Plant Protection Conf. Dec. 8-9.
Bynum, J.B., J.T. Cothren, Robert G. Lemon, and J.R. Mahan. 2004. Nodes above white flower and heat units as indicators of harvest aid timing. Proc. Beltwide Cotton Conf., Jan. 5-9, San Antonio, TX. p. 1996-1997.
May, O.L., A.S. Culpepper, R.E. Cerny, C.B. Coots, C.B. Cokern, J.T. Cothren, K.A. Croon, K.L. Ferreira, J.L. Hart, R.M. Hayes, S.A. Huber, A.B. Martens, W.B. McCloskey, M.E. Oppenhuizen, M.G. Patterson, D.B. Reynolds, Z.W. Shappley, J. Subramani, T.K. Witten, A.C. York, and B.G. Mullinix, Jr. 2004. Transgenic cotton (Gossypium hirsutum L.) expands flexibility to apply glyphosate herbicide. Crop Sci. 44:234-240.
Bynum, J.B., J.T. Cothren, and R.G. Lemon. 2004. Chaperone effects on cotton fruiting and yield. Proc. Beltwide Cotton Conf., Jan. 5-9, San Antonio, TX. p. 2189-2193.
Fromme, D.D., J.T. Cothren, and J.B. Bynum. 2004. The effect of an upper limit temperature threshold on heat calculations, defoliation timing, yield and fiber quality. Proc. Beltwide Cotton Conf., Jan. 5-9, San Antonio, TX. p. 1990-1994.
Gwathmey, C. Owen, J.B. Bynum, J.T. Cothren, K.L. Edmisten, J.T. Reed, R.P. Viator, and E.D. Vories. 2004. Adaptation of COTMAN for use in UNR cotton. Proc. Beltwide Cotton Conf., Jan. 5-9, San Antonio, TX. p. 2181.
Halfmann, S.W., J.T. Cothren, and J.B. Bynum. 2004. Seeding rate effects on yield response and last effective boll populations in cotton. 2004 Proc. Beltwide Cotton Conf. San Antonio, TX. January 5-9, 2004. p. 2280-2283.
McGuire, Cy C., J.T. Cothren, and J.B. Bynum. 2004. Physiological responses of insecticidal use on cotton. 2004 Proc. Beltwide Cotton Conf. San Antonio, TX. January 5-9, 2004. p. 2271-2274.
Niccum, Brett, M., J.T. Cothren, J.B. Bynum and T.L. Provin. 2004. Insecticidal effects on fruiting and yield enhancement in cotton. Proc. Beltwide Cotton Conf., Jan. 5-9, San Antonio, TX. p. 2255-2261.
Hundley, L.N. 2004. Physiological assessment of foliar imidacloprid treatments on cotton. M.S. Thesis. Texas A&M University. 119pp.

Progress 01/01/03 to 12/31/03

Outputs
Although Roundup Ready technology provides cotton growers with weed control advantages, previous studies have shown that over-the-top applications of Roundup (glyphosate) can potentially reduce Roundup Ready cotton lint yield. Therefore, the objectives of this project were to determine the effects of over-the-top applications of glyphosate on Roundup Ready cotton yield, pollination efficiency, and boll distribution. A two-year study was conducted at the Texas Agricultural Experiment Station, near College Station, TX. Deltapine 5690 RR was planted and maintained using conventional irrigation and insect management practices. Treatments consisted of Roundup Ultra applied at three different rates; 0.5, 1, and 2 qt/A, at three different stages of growth (4-, 8-, and 12-leaf). Rates were designed to bracket the labeled recommendation of a single over-the-top application of 1 qt/A until the 4-leaf stage. In both years, as the rate of glyphosate increased and the leaf stage of application was delayed, lint yield was reduced. In the first year, lint yield reduction was significant only for all rates within the 12-leaf stage treatments. However, significant differences were noted in the second year for the 2 qt/A rate at the 4-leaf stage, and for all rates within the 8- and 12-leaf stage treatments. Twelve hours after natural pollination, the degree of anther opening, and the number of pollen grains attached to the stigma were determined for first position flowers. In both years, as the rate of glyphosate increased and the stage of application was delayed, a greater number of anthers remained closed and fewer pollen grains were attached to the stigma. Fruiting patterns as determined by boxmapping data showed that, as the rate of glyphosate increased and the stage of application was delayed, fewer first position bolls were retained. Under these conditions, plants tried to compensate for yield losses by setting bolls at more distal positions. Lower pollen availability may have contributed to the lower first position boll retention. Additionally, the more distal position fruit tended to be smaller in size and weight. The closer the glyphosate application was to floral development, the greater the effect upon pollen availability, as determined by pollen count data. Glyphosate applied according to the label recommendation had no detrimental effects on pollination on first position flowers. Expanding the use pattern or rate of glyphosate in Roundup Ready cotton by enhancing glyphosate resistance would add flexibility for weed management. Additional studies have been initiated under field conditions to test glyphosate resistance of cotton germplasm transformed with a new gene construct imparting expanded glyphosate resistance in the greenhouse. The current glyphosate-resistance positive control ('Coker 312'-1445) and three additional transgenic cotton lines containing the same expanded glyphosate construct were tested. This study confirmed expanded glyphosate resistance imparted by the new gene construct.

Impacts
These studies documented the adverse affect of applying glyphosate off-label, and did document the increased tolerance of cotton germplasm transformed with a new gene construct for glyphosate resistance. The documentation of increased lint yield with increases up to 1050 HU beyond cutout establishes the need for additional work on NAWF = 5 and heat unit accumulation for proper harvest aid timing.

Publications

Clawson, E.L. 2003. Optimization of row spacing and nitrogen fertilization for cotton. Ph.D. Dissertation. pp. 118.
Hoffman, S.M. 2003. Cotton response to over-the-top Envoke application. M.S. Thesis. pp. 71.
Mery, Ramon F. 2003. Effects of glyphosate over-the-top application on the reproductive growth of Roundup Ready cotton. M.S. Thesis. pp. 81.
Witten, T.K. 2003. Heat unit accumulation to determine boll maturity and the influence upon fiber properties and lint yield of cotton. Ph.D. Dissertation. pp. 95.
Hoffman, S.M. and Cothren, J.T. 2003. Cotton response to over-the-top Envoke application. 2003 Proc. Beltwide Cotton Conf. Nashville, TN. pp. 1660.
Hundley, C. A., Cothren, J.T., and Smith, H.R. 2003. Do phosphate-based insecticides influence cotton growth and yield? 2003 Beltwide Cotton Conf. Nashville, TN. pp. 1663.
Mery, R.F., Cothren, J.T., Witten, T.K., and Burson, B.L. 2003. Evaluation of different rates and timing of glyphosate over-the-top application of Roundup Ready cotton. 2003 Proc. Beltwide Cotton Conf. Nashville, TN. pp. 1661.
Wall, L., Cothren, J.T., and Witten, T.K. 2003. Physiological assessment of foliar Trimax treatments on cotton. 2003 Proc. Beltwide Cotton Conf. Nashville, TN. pp. 1678.
Witten, T.K., and Cothren, J.T. 2003. Characterization of harvest by heat unit accumulation. 2003 Proc. Beltwide Cotton Conf. Nashville, TN. pp. 1671.
Clawson, E.L., Cothren, J.T. and Satterwhite, J.L. 2003. Analysis of UNR conventionally spaced cotton yield at varying nitrogen fertilizer rates. 2003 Proc. Beltwide Cotton Conf. Nashville, TN. pp. 1664.
Falkenberg, N., Piccinni, G., Owens, M.K. and Cothren, J.T. 2003. Remote sensing for site-specific management of biotic and abiotic stress in cotton. 2003 Proc. Beltwide Cotton Conf. Nashville. TN. pp.1692-1696.
Fromme, D.D., Cothren, J.T., Lemon, R.G., Witten, T.K., and Pigg, D.J. 2003. Preconditioning effects on boll opening, defoliation, fiber quality, and yield. 2003 Proc. Beltwide Cotton Conf. Nashville. TN. pp. 1666-1669.

Progress 01/01/02 to 12/31/02

Outputs
Previous studies have indicated that lint yield can be negatively impacted when cotton (Gossypium hirsutum) is treated with over-the-top Roundup (glyphosate) applications. Consequently, reproductive organs of cotton were examined for damage from glyphosate application. A field study on Deltapine 5690 RR was used to examine the impact of 3 different rates of glyphosate applied at three different stages of plant growth: 4, 8, and 12 - leaf. These rates bracketed the single over-the-top recommended rate of 1 qt/A of glyphosate until the 4-leaf stage. At 12 hours after natural pollination, the number of pollen grains attached to the stigma and the degree of anther opening was examined. A greater number of anthers remained closed and fewer pollen grains were attached to the stigma as the rate of glyphosate increased and the stage of application was delayed. Pollen tube rate of growth and length did not appear to be impacted by glyphosate treatment. However, less retention of first position fruit was observed as the rate of glyphosate increased and stage of application was delayed. Lint yield was not adversely affected by glyphosate when it was applied according to label. Continuation of studies with row spacings of 7.5, 15, and 30 inches fertilized with 0, 45, 90, and 135 lb N/A indicated that the potential for increased earliness with ultra-narrow row cotton appears real. An interaction between nitrogen and row spacing on cumulative percent seed cotton harvested caused earliness advantages (in days to 60 percent seed cotton harvest) of 7.5 inches over 30 inches rows to be evident mainly at the two highest nitrogen rates. Although the 30 inches rows had a high percentage of bolls at lower fruiting nodes and in the first position, this response was not as marked as within the 7.5 inches spacing.

Impacts
Although vegetative tolerance of Roundup Ready cotton is acceptable, there can be a lack of tolerance in reproductive organs, especially if the product is applied outside the label. Producers should adhere strictly to label to avoid potential lint yield reductions. Ultra-narrow cotton production appears to offer earliness in maturity that could translate to earlier harvest. However, from our studies there does not appear to be a yield advantage to ultra-narrow production.

Publications

Clawson, E.L. and J.T. Cothren. 2002. Influence of row spacing and nitrogen rate on earliness components and yield of cotton. CD ROM. Beltwide Cotton Conference, Atlanta, GA - January 8-12.
Witten, T.K. and J.T. Cothren. 2002. Heat, maturity, and defoliation. CD-ROM. Beltwide Cotton Conference, Atlanta, GA - January 8-12.
Hoffman, S.M. and J.T. Cothren. 2002. Effect of CGA 362622 on cotton growth and development. CD-ROM. Beltwide Cotton Conference, Atlanta, GA - January 8-12.
Mery, R.F., J.T. Cothren, T.K. Witten, and B.L. Burson. 2002. Effects of glyphosate on Roundup Ready cotton reproductive growth. CD-ROM. Beltwide Cotton Conference, Atlanta, GA - January 8-12.
Jasoni, R.L., J.T. Cothren, P.W. Morgan, and D.E. Sohan. 2002. Circadian ethylene production in cotton. Plant Growth Regulation. 36 (2):127-133.
Viator, R.P., W. Pline, R. Wells, K. Edmisten, J. Wilcut and J.T. Cothren. 2002. Glyphosate effects on reproductive development. CD-ROM. Beltwide Cotton Conference, Atlanta, GA - January 8-12.

Progress 01/01/01 to 12/31/01

Outputs
Ultra - narrow row cotton (Gossypium hirsutum) is considered a potential strategy for reducing production costs by shortening the growing season. A 2 - yr. field study was conducted on varying soil types near College Station, TX to document phenotypic alterations and crop maturity differences for cotton grown in 19-, 38-, 76-, and 101- cm row spacings. In the 19-cm rows, the plant densities were 12.2, 18.8, and 40.5 plants m-2. Densities of 11.3 and 19.5 plants m-2 were established in the 38-cm rows. In the 76- and 101-cm rows, plant densities of 11.7 and 7.4 plants-2, respectively, were evaluated. Plant height and node counts were reduced in the narrow (19 and 38 cm) row spacings in only 1 yr. At the higher plant densities, cotton in the narrow row spacings consistently accumulated leaf area index more rapidly than the conventional (76 and 101 cm) row spacings. In one of the years, when the study was conducted on a heavy clay soil, the higher plant densities in the narrow row spacings tended to partition more biomass to reproductive structures and yielded more than the conventional row spacings. However, when the trial was conducted on a lighter silty clay loam soil, yields were unaffected by the row-spacing treatments. The higher plant densities in the narrow row spacings had a greater percentage of harvestable bolls at the first fruiting position on lower nodes, a boll distribution pattern that contributed to earlier crop maturity in the year the study was grown on the heavier soil. Fiber quality was not consistently altered by the narrow row spacings and high plant densities. This study suggested that ultra-narrow row cotton may be more advantageous to producers when grown on heavier soils that typically do not promote excessive vegetative growth. An additional study examined yield and earliness responses of cotton in three row spacings (7.5, 15, and 30") and four different levels of nitrogen (0, 45, 90, and 135 lb/acre). Days to 60 percent of total seedcotton harvest were approximated by plotting percent seedcotton harvested versus days after planting. The 135 and 90 lb N/acre treatments showed virtually no difference in this estimate of earliness, while the 45 lb N/acre treatments appeared to be slightly later, and the 0 lb N/acre treatment was approximately four to five days later. A similar estimation showed no apparent earliness difference between 7.5" and 15" rows, both of which reached 60 percent seedcotton harvest approximately two days before the 30" row spacings. Lint yields increased with increasing levels of nitrogen, but there was no significant nitrogen by row spacing interaction on total lint yield. Preliminary indications from this study are that 7.5"rows do not require lower nitrogen fertilizer levels than 15 or 30" rows. Also, there is insufficient evidence to recommend higher nitrogen rates.

Impacts
Results from the ultra-narrow studies in cotton continue to show a degree of earliness associated with more narrow spacings (7.3 and 15") than is found in conventional row spacings (30 and 40"), leading to earlier harvest. Yield advantage from the ultra-narrow spacing, however, is inconsistent. Initial observations suggest the ultra-narrow concept may be better suited for heavier soils than for lighter soils.

Publications

Viator, R.P., J.T. Cothren, and S.A. Senseman. 2001. Response of Roundup Ready cotton to Roundup Ultra. Proc. Beltwide Cotton Conf. p. 447.
Witten, T.K., J.T. Cothren, and R.G. Lemon. NAWF and heat unit accumulation for determining cotton defoliation. 2001. Proc. Beltwide Cotton Conf. p. 447.
Clawson, E.L. and J.T. Cothren. 2001. Row spacing and nitrogen effects on yield and earliness of cotton. Proc. Beltwide Cotton Conf. p. 459.
Nuti, R.C., T.K. Witten, and J.T. Cothren. 2001. Growth and yield comparisons of PixPlus and additional Bacillus cereus treated cotton. Proc. Beltwide Cotton Conf. p. 459.
Jost, P.H. and J.T. Cothren. 2001. Phenotypic alterations and crop maturity differences in ultra-narrow row and conventionally spaced cotton. Crop Sci. 41:1150-1159.
Viator, R.P. 2001. Influence of Glyphosate on Growth and Yield of Glyphosate - Tolerant Cotton. 2001. M.S. Thesis. Texas A&M Univ. 60 pp.

Progress 01/01/00 to 12/31/00

Outputs
Rising production costs and static crop prices continue to face cotton (Gossypium hirsutum) growers. One strategy for reducing production costs, by shortening the growing season, is to grow cotton in ultra-narrow rows (UNR) with elevated plant densities. Differences in vegetative and reproductive growth of cotton was assessed in a three-year field study. Four row spacings of 7.5, 15, 30, and 40 inches were included; plant densities in the 7.5 -inch rows were 40,000, 75,000, and 120,000 plants/A. Densities of 40,000 and 75,000 plants/A were established in the 15-inch rows. Conventional plant densities were evaluated in the 30- and 40-inch row spacings. Regardless of plant density, plant height was reduced in the 7.5-inch row spacing, in only one year. Total node counts were reduced in the 7.5-inch rows with the high density in two of the three years. The 7.5- and 15-inch row spacings with the higher plant densities reached canopy closure most rapidly of the treatments examined. Although plants in the higher densities had less leaf area per plant and smaller plants, these treatments accumulated leaf area index and produced biomass more rapidly than the conventional row spacings. An additional field study was conducted to evaluate the response and/or performance of eight cotton varieties in an UNR system. The varieties included: DP 436 RR, DP 5690 RR, DP 5415 RR, DP 458 B/RR, DP 655 B/RR, DP 409 B/RR, PM 2280 BG/RR, and PM 1220 BG/RR. These varieties were planted to 7.5- , 15-, and 30-inch row spacing with plant populations of 160,000, 100,000, and 52,000 plants/A, respectively. All varieties collectively demonstrated the same characteristics within a given row spacing, i.e., no variety by spacing interactions were observed for any of the parameters examined. Assessment of plant height, total nodes, canopy closure, maturity, boll distribution, or boll size showed no varietal differences. An increase in lint yield compared to other varieties was observed in DP 436 RR and PM 1220 BG/RR, which had significantly more bolls per plant than all other varieties. No varietal influences were noted for lint quality when determined by HVI analysis, as all characteristics were within acceptable ranges. Canopy closure occurred more rapidly in the 7.5- and 15-inch spacing compared to the 30-inch spacing. At match-head square (45 DAP), the 7.5- and 15-inch spacing had 75 and 50% canopy closure, respectively, compared to 26% closure in the 30-inch spacing. Also, plant height and total nodes were reduced in UNR compared to conventional cotton. Total boll number decreased as row spacing decreased, with the 7.5-, 15-, and 30-inch spacing having 4.7, 6.6, and 9.5 bolls per plant, respectively. In addition, first position fruit retention was higher in UNR spacing than in the conventional spacing. No differences in vegetative to reproductive ratios were observed. Although seedcotton/boll decreased as row spacing decreased, lint yield was significantly increased in UNR cotton compared to the conventionally spaced planted cotton.

Impacts
Information generated in these studies reinforced that UNR cotton matures more rapidly than a conventional row spacing and could be used in a situation when earlier maturity is warranted. Also, UNR cotton closes the plant canopy quicker, and may be used where length of the growing season is shortened.

Publications

Jost, P.H. and J.T. Cothren. 2000. Growth and yield comparisons of cotton planted in conventional and ultra-narrow row spacings. Crop Sci. 40: 430-435.
Jost, P.H. and J.T. Cothren. 2000. Evaluations of cotton plant density in ultra-narrow and conventional row spacings. Proc. Beltwide Cotton Conf. pp. 659-660.
Steglich, E.M., T.J. Gerik, J. Kiniry, J.T. Cothren and R.G. Lemon. 2000. Change in the light extinction coefficient with row-spacing in upland cotton. Proc. Beltwide Cotton Conf. pp. 606-608.
T.K. Witten and J.T. Cothren. Varietal comparisons in ultra-narrow row cotton (UNRC). 2000. Proc. Beltwide Cotton Conf. p. 608.
T.J. Gerik, R.G. Lemon, A. Abrameit, T.D. Valco, E.M. Steglich, J.T. Cothren, and J. Pigg. Using ultra-narrow rows to increase cotton production. 2000. Proc. Beltwide Cotton Conf. p. 653.
Underbrink, S.M., R.P. Viator, T.K. Witten, and J.T. Cothren. 2000. Responses of ultra-leaf cotton to competitive populations. Proc. Beltwide Cotton Conf. p. 684.
Nuti, R.C., T.K. Witten, P.H. Jost, and J.T. Cothren. 2000. Comparisons of Pix Plus and additional foliar Bacillus cereus in cotton. p. 684.

Progress 01/01/99 to 12/31/99

Outputs
Cotton grown in ultra-narrow row spacing is being investigated as a means to improve production efficiency. An experiment in 1998 included spacings of 7.5, 15, 30, and 40 inches. Plant population in the row spacings were 186K, 77K, 55K, and 40K, per acre, respectively. Canopy closure at match-head square was greater than 50% in the 7.5-inch spaced cotton, but was less than 30% in all other spacings. Canopy closure had approached 100% in the 7.5- and 15-inch row spacings by early bloom, but was less than 70% in the conventional spacings. Leaf biomass per plant was significantly less in the 7.5-inch row spacing than for all other row spacings. Also, more than 60% of the total harvestable yield was collected 10 and 6 days earlier in the 7.5- and 15-inch spaced cotton, respectively, than in cotton grown in the 30- and 40-inch row spacing. Yield was at least 130 lbs/A greater in the narrow spacings than in the conventional row spacings. In additional studies, no significant differences were detected in the growth rate between Bt and conventional cotton varieties. For mepiquat chloride (MC) use, it was concluded that Bt varieties behave similarly with respect to vegetative growth to application of MC as their conventional counterparts. Therefore, current MC application rate strategies should suffice for suppressing rank vegetative growth of Bt cotton.

Impacts
(N/A)

Publications

Witten, T.K. 1999. Influence of polyaspartic acid on growth and yield of cotton. M.S. Thesis. 107 pp.
Underbrink, S.M. 1999. Agronomic differences in growth and yield between Bt and conventional cotton treated with mepiquat chloride. M.S. Thesis. 142 pp.
Viator, R.P., P.H. Jost, and J.T. Cothren. 1999. Do cotton varieties respond differently to plant growth regulators? Proc. Beltwide Cotton Conf. p. 602.
Jost, P.H. and J.T. Cothren. 1999. Is ultra-narrow row earlier than conventionally-spaced cotton? Proc. Beltwide Cotton Conf. p. 640.
Witten, T.K., P.H. Jost, and J.T. Cothren. 1999. Evaluation of cotton harvest aids in the Brazos Bottoms. Proc. Beltwide Cotton Conf. p. 617-620.
Biles, S.P., T. Cothren, J. Landivar, and G. Teetes. 1999. Flowering responses to mepiquat chloride and PGR-IV. Proc. Beltwide Cotton Conf. p. 547.
Witten, T.K., P.H. Jost, and J.T. Cothren. 1999. Planting date and growth regulator influences on cotton growth and yield. Proc. Beltwide Cotton Conf. p. 559.

Progress 01/01/98 to 12/31/98

Outputs
Carpramid, polyaspartic acid (PA), is a long-chained synthetic protein that has been reported to increase nutrient availability and uptake in various plants. A two-year study was conducted in the Brazos Bottoms of Texas using different rates of soil-applied PA with varying nitrogen fertility treatments in cotton (Gossypium hirsutum) to examine its effects on growth and yield parameters. Lint yields from treatments using 90 and 150 lbs. N/acre were greater than those using 30 lbs. N/acre, but yield was unaffected by PA in the soil-applied studies. An additional one-year study was conducted at two locations with foliar applications of PA in combination with a micronutrient source, which showed that the micronutrient source and a 4 qt/A rate of PA yielded significantly more lint/A than did the untreated control. In separate studies, ethylene production in cotton was examined under 12 h light/12 h dark and continuous light treatments to determine if ethylene and the enzymes associated with its production are under the control of a biological rhythm. Patterns of ethylene, 1 - (malonylamino) cyclopropane -1 - carboxylic acid, and 1 - aminocyclopropane - 1 - carboxylic acid (ACC)production were similar in both photoperiod treatments, indicating the production of these products is at least partly controlled by a biological rhythm. A significantly greater amount of ethylene was produced in the continuous light treatment compared to that produced in the 12 h light/12 h dark treatment, suggesting that ACC oxidase could possibly be influenced by photoperiod. An additional two-year field study was conducted to determine whether beneficial responses could be obtained from plant growth regulators in cotton using four treatments: an untreated control, mepiquat chloride (MC), PGR-IV, and a combination of both MC and PGR-IV applied sequentially. The MC and PGR-IV + MC treatments increased the season-long average flower production relative to the untreated control. Treatment effect on flower survival was different only for flowers that bloomed between the 36th and 40th day of flowering. All PGR treatments increased lint yield and boll numbers compared to the untreated control.

Impacts
(N/A)

Publications

Witten, T.K., J.T. Cothren, and F.M. Hons. 1998. Cotton responses to foliar and in-furrow applied Amisorb and fertility treatments. In: Proc. Beltwide Cotton Prod. Conf., National Cotton Council, Memphis, TN. pp. 1475-1479.
Jasoni, R.L. and J.T. Cothren. 1998. Biological rhythms of ethylene production in cotton. In: Proc. Beltwide Cotton Prod. Conf., National Cotton Council, Memphis, TN. pp. 1376-1377.
Jasoni, R.L. 1998. Rhythms of ethylene production and stomatal conductance of cotton. Ph.D. Dissertation. Texas A&M University. 151 p.
Biles, S.P. 1998. Cotton responses to mepiquat chloride and PGR-IV treatments. M.S. Thesis. Texas A&M University. 69 p.
T.K. Witten, J.T. Cothren, and F.M. Hons. 1997. Cotton responses to carpramid. Agron. Abst. p. 114.