Effect of Plant Water Status on Defoliation and Yield of Pima Cotton
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AbstractA field study was conducted at the Maricopa Agricultural Center to determine the influence of plant water status at the time of defoliation on the effectiveness of defoliants and the yield of Pima cotton. Irrigation termination dates of 3 and 20 September and 8 October were used to achieve different levels of plant water stress at the time defoliants were applied (26 October). A single application of defoliants was not adequate to defoliate the cotton under the conditions of this test. The 3 September irrigation termination date resulted in the highest percentage of defoliation (63 %). CWSI and plant water content (RWC) measurements indicated that the irrigation termination treatments resulted in large differences in plant water stress at defoliation time. There was a significant increase in the percent defoliation as the CWSI values increased from 0.54 to 0.99.