Project Summaries

11-941  Project Manager: P. F. O'Leary

USE OF COTMAN CROP MONITORING PROGRAM TO HELP PREDICT WHEN TO APPLY PLANT GROWTH REGULATORS

Derrick M. Oosterhuis, University of Arkansas, and Tom Cotheran, Texas Agrilife Research

COTMAN is a computerized decision aid that integrates information on plant growth patterns, current and historical weather data and farm and field parameters to enhance cotton crop management. Basically, COTMAN is a crop monitoring system that utilizes selected plant indicators to follow plant development and fruit load from initiation of squaring through effective flowering. COTMAN consists of two expert systems, SQUAREMAN (primarily used to monitor pre-flowering plant development) and BOLLMAN (used to monitor post-flowering plant development). The advantages of COTMAN are that it provides continuous in-season crop monitoring to assist in achieving earliness timely feedback on plant development, early detection of plant stress. The program makes use of a Target Development Curve as a benchmark for earliness. COTMAN provides end-of-season management decision aids based on cutout date for insecticide termination timing, fields ranking by maturity, and defoliation and harvest timing However, despite the accurate manner in which COTMAN tracks nodal development and fruiting sites, there is no current relation to the need for PGRs to control excessive growth.

The COTMAN plant growth monitoring program consists of two expert systems: SQUAREMAN (which uses SquareMap data) and BOLLMAN (which uses nodes-above-white-flower, NAWF) data. Both expert systems primarily utilize one common plant measurement, the number of SQUARING NODES. The number of SQUARING NODES is indicator of the fruiting dynamics of the plant throughout the effective fruiting period. The pace of development of the crop is clearly shown by comparison with a standard target development curve. It would seem logical to be able to make use of these two quantification measurements of crop growth to predict when the crop is either developing too slowly, or growing too rapidly. This should then allow the producer to decide when to apply mepiquat chloride or when not to. The objective of this study, therefore, is to produce various crop vigor scenarios, using water and nitrogen, and then use the COTMAN target development curve together with other indices from COTMAN to determine when to apply mepiquat chloride.

RESULTS AND DISCUSSION:
The study was conducted in Marianna, Arkansas, and College Station, Texas. Recommended management practices were used. Treatments consisted of (a) two water regimes and two nitrogen regimes, to give four different canopy growth habits. These were to be split with mepiquat chloride applied according to the COTMAN curve. Records included weekly SQUAREMAN and BOLMAN records, including cutout (NAWF5) and time of defoliation (NAWF5_850 heat units), plant height and number of main-stem nodes, meteorological records (maximum and minimum temperature and rainfall), irrigation records, yield, boll number and boll weight, yield, gin turnout, and fiber HVI quality.

CONCLUDING REMARKS:
In both locations, Arkansas and Texas, the season was AN unusually hot and dry record season which resulted in very little growth differences between the nitrogen and water treatments, and therefore there was little requirement for mepiquat chloride. The irrigation treatment was significant, but neither the effect of fertilizer N Rate nor the interaction between fertilizer N Rate and Irrigation significantly impacted lint yield in pounds per acre. The early slopes of the COTMAN curves in relation to the Target Development curve did not call, for any PGR (mepiquat chloride) application.

The study should be repeated with some modification to the treatments to ensure that we get suitable crop canopy differences that can be detected by COTMAN so as to call for mepiquat chloride applications according the slope of the SQUAREMAN and BOLLMAN curves. The study could also be conducted in large walk-in growth chambers so as to adequately control the environment and also ensure the proper nitrogen and waters treatments to achieve the COTMAN curves we want allow PGR applications, so as to test the ability of the COTMAN curves prior to the apogee for predicting PGR applications to enhance or inhibit crop growth. This type of data and prediction would add immeasurably to the COTMAN program for improving early season prediction and control of growth.

 

Project Year: 2012
 

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