M.A. Thesis:

Effect of concentration and time of foliar application of potassium humate on yield٫ yield components and protein content of forage sorghum

In order to evaluate the effect of concentration and time of foliar application of potassium humate on yield and quality of forage sorghum, a factorial experiment based on randomized complete block design with three replications was done in Sabzevar. Experimental factors included three concentrations of potassium humate (0, 0.03 and 0.06%) and time of foliar application in three levels of foliar application at 6-8 leaf stage, foliar application at emergence of inflorescences and two foliar applications at 6-8 leaf stage and emergence of inflorescences. The results showed that concentration of potassium humate had no significant effect on leaf number per plant and protein content of forage. The foliar application of different concentrations of potassium humate increased plant height; fresh forage yield, dry matter percentage of forage and nitrogen uptake compared to non-foliar application treatment, but decreased tiller number per plant. There were no significant differences between potassium humate foliar application at concentrations of 0.03 and 0.06% in relation to plant height and nitrogen uptake. The highest fresh forage yield and dry matter percentage was obtained in potassium humate foliar application at concentration of 0.06%, which had a significant increase compared to the concentration of 0.03%. The effect of time of potassium humate foliar application on all characteristics was significant. Two foliar applications of potassium humate with a concentration of 0.06% in 6-8 leaf stage and emergence of inflorescence produced the highest fresh forage yield and dry matter content of forage. However, the highest percentage of protein and nitrogen uptake was obtained by two foliar applications of potassium humate at concentration of 0.03% in 6-8 leaf stage and emergence of inflorescence. The highest plant height of sorghum was observed in two foliar applications of potassium humate at concentration of 0.03% in 6-8 leaf stage and emergence of inflorescences, which had no significant difference with foliar application of 0.03% potassium humate at 6-8 leaf stage and also with foliar application of 0.06% potassium humate in 6-8 leaf stage and 6-8 leaf stage + emergence of inflorescence. According to the results, two foliar applications of potassium humate at concentration of 0.06% in 6-8 leaf stage and emergence of inflorescence is recommended for production of maximum fresh forage yield with high dry matter content of sorghum.

Keywords: : potassium humate, leaf number, nitrogen uptake, forage quality, foliarapplication.