Foliar applied potassium nitrate stimulated square development in cotton

Although the application of foliar KNO3 has been shown to increase the number of squares, it was uncertain whether this effect was due to the K+ or the NO3-. Therefore a study was conducted in the USA to evaluate the influence of different foliar-applied salts on square development of two cotton varieties that differ in maturity and root morphology. Plants were transferred to a K-free nutrient solution 21 days after planting and one of the following salts, KNO3, K2SO4 or NH4NO3 was foliar applied at an equivalent rate of 11,2 kg/ha KNO3. Control plants were applied with an equivalent volume of water without nutrients. The experiment was conducted in a randomized complete block design with three replications. The foliar treatment of KNO3 increased the number of squares by 31% compared to the control, 29% compared to K2SO4 and 49% compared to NH4NO3 (Figure 1). This finding suggests that K+, not NO3-is responsible for the improved square development with foliar-applied KNO3. Application of KNO3 several days before square development resulted in increased square number if K is limiting. Potassium nitrate outperformed other salts in foliar application where a response to K is desired.


Figure 1. Effect of foliar treatments on square formation in cotton. Means followed by the same letter are not significantly different at P=0,05 using protected LSD.


Keino, J. K., C.A. Beyrouty, E.E. Gbur, and D.M. Oosterhuis. 1997. Effect of foliar-applied nutrients on square development of cotton. Special Reports-University of Arkansas Agricultural Experiment Station, 183: 108-111.

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