A field study was conducted at the Maricopa Agricultural Center to determine the effect of nitrogen fertility level and growth regulators on earliness, yield of cotton, and effectiveness of defoliants. Nitrogen application rates of 80, 120 and 160 lbs N/A did not influence lint yields or the response of cotton to growth regulators. The growth regulator Piz tended to promote earliness but did not affect final yield. The defoliants tested achieved good leaf drop results independent of the plant nitrogen status. Petiole nitrate-N content at the time of defoliation (4 October) did not correlate well with the response of cotton to defoliation treatments.
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