Monday, 20 June 2005 - 10:45 AM
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This presentation is part of 5: Crops--Forage, Sugarcane, Rice, and Cotton

Effect of Skippy Cotton Stand on Yield.

Philip Jost, University of Georgia, PO Box 8112 GSU, Statesboro, GA 30460 and Alexander Stewart, Lousianna State University, 8105 Tom Bowman Drive, Alexandria, LA 71302.

Studies were established in East Georgia and South Louisiana to examine the effects of skippy cotton stands on yield. The objective of the trial was to determine what skip lengths and frequency were critical for predicting yield loss. Random skips were established by planting varying ratios of Liberty Link and non-Liberty Link cotton seed in plots consisting of four 38-inch rows 40 feet long. Plots were treated with Ignite to remove the non-Liberty Link plants thus establishing skips of varying length and frequency. At harvest, the distances between each plant in the two center rows were measured. These two rows in each plot were then harvested. The summation of total skip lengths per 80 feet of row were tabulated for skips ranging from 1 to 4 feet in 0.5 ft increments. Data were analyzed by regression analysis using yields as the dependent variable and skip length and frequency as the independent variables. Stepwise variable selection was utilized to isolate which measurements most accurately modeled final plot yield. Yield loss was most affected by skip lengths of 2 and 3.5 feet. Skips less than 2 feet had no effect on yield. For every 80 foot of row, a skip of 2 feet in length reduced yield by 4.7 lbs lint/A, while a skip of 3.5 feet in length reduced yield by 8.0 lbs lint/A. Thus yields from a stand comprised primarily of 2 foot skips will not be as compromised as one possessing a large number of 3.5 foot skips. The resulting model will allow for simple measurements to be made on a less than desirable stand and predict yield loss compared to an optimal stand. These data will be a valuable tool for county agents and crop consultants attempting to aid farmers in making replant decisions.

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