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Evaluation of Plant Growth Regulators with Varying Nitrogen Management

M.W. Ebelhar, R.A. Welch


Various plant growth regulators have been studied and used for many years around the country to reduce or stimulate all aspects of plant development. They have been proposed to interact with higher N rates to produce higher lint yields. A 3-year study was established at the Delta Research and Extension Center, Stoneville, MS to evaluate the interaction of nitrogen (N) management and plant growth regulator (PGR) systems. A factorial arrangement of N management systems (120 and 160 lb N/A applied 100% preplant (PP) or 50% PP plus 50% sidedressed) and PGR systems (mepiquat chloride [Pix] and PGR-IV) were included in a randomized complete block design with five replications. The PGR systems included 1) an untreated control (UTC; 2) Pix applied at a rate of 4 oz/A/ applicationfor a total of 16 oz/A (applied bi-weekly) ; 3) PGR-IV applied at the 3-4 leaf stage (1 oz/A), at pin-head square (2 oz/A), and at first bloom (4 oz/A): and 4) Pix plus PGR-IV at the above rates and timing. There was no significant lint yield response to N rates or to split applications throughout the study nor when averaged across years. Pix applications increased lint yield increases in two of the three years and when averaged across years. There was no lint yield increase associated with the application of PGR-IV when averaged across N management systems. When both Pix and PGR-IV were used in combination, the lint yield increase was lower than with Pix alone.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1415 - 1418
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998