M.A. Thesis:

Effect of foliar application of potassium humate on yield and yield components of cotton under full and deficit irrigation

Abstract: In order to evaluate the effect of foliar application of potassium humate on yield and yield components of cotton under full and deficit irrigation, a split plot experiment based on randomized complete block design with three replications was done in agriculture lands of Steer, Sabzevar. Experimental factors were: Irrigation at two levels of deficit and full irrigation as the main plot and concentration of potassium humate for foliar application in five levels (Control, 0.015, 0.03, 0.045 and 0.06 %) as the sub polt. Potassium humate was foliar applied at two stages of vegetative growth and beginning of reproductive growth. The results showed that leaf chlorophyll index, seed numbers per boll and fiber percentage of cotton were not affected by irrigation treatments. Deficit irrigation significantly reduced plant height, number of lateral branches of the stem, boll number per square meter, cotton yield, biological yield, seed weight, boll weight and harvest index compared to full irrigation treatment. Foliar application of potassium humate increased leaf chlorophyll index, number of lateral branches of the stem, boll number per square meter, cotton yield and biological yield compared to no foliar application treatment. The highest chlorophyll index was observed at 0.045% potassium humate concentration. In deficit irrigation conditions, potassium humate foliar application with a concentration of 0.06% produced the highest boll number per square meter, cotton yield and biological yield. While, in full irrigation conditions, the highest boll number per square meter, cotton yield and biological yield were obtained with potassium humate foliar application at concentration of 0.045%. Foliar application of potassium humate had no significant effect on cotton harvest index in full irrigation, but the concentration of 0.06% potassium humate significantly increased the cotton harvest index in deficit irrigation conditions. According to the results, two foliar application of potassium humate at concentrations of 0.045 and 0.06% in vegetative growth and beginning of reproductive growth, are recommended for production of maximum yield of cotton under full and deficit irrigation conditions, respectively. Key word: cotton, chlorophyll index, deficit irrigation, foliarapplication, potassium humate.

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