• Evaluation of Two Plant Growth Regulators from LT Biosysn

      Norton, E. R.; Clark, L. J.; Borrego, H.; Ellsworth, Bryan; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2005-05)
      A single field study was conducted during the 2004 cotton growing season at the University of Arizona Safford Agricultural Center to evaluate the effect of two plant growth regulators (PGRs) manufactured by LT Biosyn Inc. on the growth, development, yield, and fiber quality of cotton grown in the southeastern region of the state. This test was designed as a follow up study to work that was performed in 2003 on a grower cooperator site that demonstrated positive lint yield responses to the use of one of the PGRs used in this project. This was an eight treatment test involving the application of two PGRs, HappyGroTM (HG) and MegaGroTM (MG). The two formulations are intended to have different effects on plant growth and development. The HG formulation is a kinetin based product designed to enhance cell division and differentiation. The MG formulation is designed to enhance root growth early in the season. Several treatment combinations were designed to investigate varying scenarios of application of these two products alone and in conjunction with each other. The test included a control and each treatment was replicated four times in a randomized complete block design. Plant measurements were collected throughout the season to look for differences in plant growth and development. Lint yield was estimated by harvesting the entire plot and weighing the seedcotton with a weigh wagon equipped with load cells. Sub samples were collected for fiber quality and percent lint determinations. Plant measurements revealed extremely high fruit retention levels throughout the entire season with end of season levels near 75%. This high fruit retention resulted in very low vigor. Under these conditions, while lint yield was extremely high for this region (1300-1600 lbs. lint per acre), no statistical differences were observed among treatments. Fiber quality measurements also revealed no significant differences.
    • Evaluation of Variable Rate Fertilizer Applications in an Arizona Cotton Production System

      Norton, E. R.; Clark, L. J.; Borrego, H.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2005-05)
      A project was initiated in the 2004 cotton (Gossypium hirsutum) growing season in an effort to accomplish two major objectives. The first was to continue with phosphorus (P) fertilization evaluations that have taken place in the Upper Gila River Valley for the past four seasons by continuing to document the effects of P fertilization on crop yield and fiber quality. The second objective was to investigate the feasibility of utilizing a Global Positioning Systems (GPS) and Geographic Information Systems (GIS) technology for making variable rate (VR) applications of P fertilizers based upon yield data from the previous cropping season. Yield maps from a cotton picker mounted yield monitoring system were collected from the 2003 growing season and used to develop prescription applications of P fertilizers in the 2004 season. The project was established with four treatments including a control (Treatment 1 - 0 P fertilizer applied); a VR application treatment (Treatment 2 - received 52 lbs P/acre on average); a high Uniform Rate (UR) application (Treatment 3 - 75 lbs P/acre); and a low UR application (Treatment 4 - 45 lbs P/acre). These treatments were arranged in a randomized complete block design with four replications. The size of each experimental unit was 0.7 acres. Lint yield results indicated a positive response to applied P fertilizers with treatments 2, 3, and 4 producing significantly higher yields than the control. Lint yield was not significantly affected by fertilizer application technique. Yield differences among the treatments receiving P fertilizer were minimal, particularly among treatments 2 and 3. However, it is important to note that the amount of P fertilizer used in treatment 2 was reduced by 27% with the use of the VR application technique. This produces an approximate $7/acre savings to the grower. This project will be continued in the 2005 growing season and will be expanded to investigate VR application technology in nitrogen (N) fertilization also.
    • On-Farm Evaluation of Mepiquat Formulations in Southeastern Arizona

      Norton, E. R.; Clark, L. J.; Borrego, H.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2005-05)
      A single field trial was conducted during the 2004 season to evaluate three different mepiquat formulations used to control vegetative plant growth. This project involved the evaluation of mepiquat formulations of Mepex Ginout (DuPont), Pix Ultra and Pentia (BASF). These three treatments, along with a control, were arranged in a randomized complete block design with four replications. Plots were 20, 36” wide rows and extended for a full one half mile irrigation run. Applications of all treatments were made on 22 July 2004 at a rate of 16 oz/acre for each formulation. Lint yields were determined at the end of the season by harvesting the center eight rows of each plot. The harvested seed cotton was weighed using a weigh wagon equipped with load cells. Sub samples were collected from each plot for fiber quality and lint percent determinations. No significant differences were observed among treatments with respect to any of the fiber quality parameters measured. The Mepex Ginout treatment produced the highest lint yield and also the highest percent lint. The control was not significantly different from the other two formulation treatments. Lint percent values had a major impact on lint yield. The control had the lowest seed cotton yield but because of the higher percent lint values, lint yield for the control was ultimately higher than both the Pentia and Pix Ultra treatments. This study demonstrates the positive effect of the PGR applications and also the effect that percent lint can have on final lint yield.
    • Upland Variety Testing Evaluation in Southeastern Arizona

      Norton, E. R.; Clark, L. J.; Borrego, H.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2005-05)
      Two separate variety evaluations were conducted in southeastern Arizona during the 2004 cotton growing season. The two locations were on grower-cooperator fields in the Upper Gila River Valley located in Thatcher, AZ (Graham County) and in the Sulfur Springs Valley in Kansas Settlement, AZ (Cochise County). Twelve varieties were selected for the Graham County evaluation and fifteen in the Cochise County evaluation. These varieties included several transgenic varieties and ranged in maturity from early to full-season varieties. Several Acala varieties were also evaluated in both the Graham and Cochise County tests. Both evaluations were conducted using a randomized complete block design with each variety replicated four times. Plant measurements were collected in season on several dates from the Graham County evaluation. End of season plant measurements were collected from the Cochise County evaluation. Lint yield was estimated at each location by harvesting the entire plot and weighing the harvested seed cotton with a weigh wagon equipped with load cells. Sub samples were collected from each plot for fiber quality and percent lint determinations. Total crop value for each variety was calculated by using the fiber quality premium/discount and using a $0.52 per pound price. The total price is then multiplied by total lint yield to obtain the total value for that particular variety. Results observed in the Graham County evaluation were similar to those in 2003. Lint yield ranged from 1200 to over 1600 lbs. lint/acre. The FiberMax variety FM991BR produced the highest lint yield and also the highest total crop value at over $950/acre. Results from the Cochise County evaluation demonstrated the potential that high fiber quality can have on total crop value. Lint yields ranged from 600 to over 1200 lbs. lint/acre. The highest yielding variety (ST5242BR) did not produce the highest crop value. Because of the higher fiber quality of the Acala varieties, they produced the highest value at approximately $630/acre.