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Water Deficit and K Partitioning in Cotton

Dennis L. Coker and Derrick M. Oosterhuis


 
ABSTRACT

The impact of water deficit on potassium K deficiency and partitioning in the cotton (Gossypium hirsutum L.) plant during peak boll development is not well understood. Inconsistent yield responses to soil and foliar-applied K fertilizers may be related to water deficit stress from irrigated or rain- fed systems. Cotton growth, lint yield, and K partitioning under limited K and water were studied in a field environment. Eight treatment combinations of well-watered or dryland conditions, high or low soil K, and with or without foliar-applied K were arranged in a split-split plot design with six replications. Growth, dry matter, leaf photosynthesis, and K concentration in above-ground organs were measured at key phenological stages [pinhead square (PS), first flower (FF), first flower + 3 weeks (FF+3), and first flower + 5 weeks (FF+5)]. Final lint yield was determined by mechanical harvest and components of yield were determined by hand harvesting. At FF+3 (peak boll development stage), stem and petiole K concentrations were significantly reduced (P 0.05) from high to low soil K under the well-watered, but not the dryland, conditions. Foliar application of K consistently increased stem, petiole, and leaf K concentration only under the low soil K condition. Foliar application of K increased leaf K concentration by a greater margin under dryland, low soil K compared to well-watered, low soil K conditions. Lint yield responded best to foliar K under low soil K and under well-watered conditions. Potassium deficiency in cotton appeared to be exacerbated by water deficit, although water deficit did not reduce the efficacy of foliar-applied K.



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pp. 634 - 636
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000