Effects of Foliar Application of Leonardite, Nitrogen, and Potassium on Root Growth, Nutrient Uptake and Yield of Wheat

This study was carried out to evaluate the effects of soil and foliar applied chemical fertilizers and foliar organic acids (as leonardite; a mixture of humic and fulvic acids) on yield and yield components and nutrient uptake by wheat. The experiment was laid out in Gorgan University of Agricultural Sciences and Natural Resources Farm during 2013- 2014, using a split-plot design with four replications. Treatments included potassium application and without potassium in the main plots and foliar applications of nitrogen, potassium, and leonardite from two different sources (Humic Power, mega humat) and a control without foliar application in subplots. Maximum root length before heading was obtained by Humic Power (11.6 cm) and, at harvest, by megahumat (16.4 cm), both in potassium treated sub plots. Root weights also followed the same trend. This may be due to growth stimulating effects of humic acids. Greatest phosphorous uptakes were 19.2 and 48.75 kg.ha-1 by straw and grain, respectively, by foliar application of megahumat in soil potassium applied plots. Foliar applications of nitrogen and potassium also enhanced nitrogen and potassium uptake, respectively. The interactions between foliar and soil applied treatments on stem length and straw yield were significant by analysis of variance. Their combined application significantly improved plant height and straw yield. This research showed that yield by foliar application of leonardite (from both sources) was greater than yield by foliar use of nitrogen and potassium irrespective of soil potassium applications. Soil potassium applications enhanced yield and nutrient uptakes by foliar treatments.