POTASSIUM HUMATE APPLICATION ON GRAIN YIELD-RELATED TRAITS OF CORN

This study was conducted to evaluate potassium humate application for reducing the effect of water deficiency on corn crop. Experimental design was factorial split plot experiment on randomized complete block with three replications at Tabriz Branch, Islamic Azad University. Factor A included irrigation levels (irrigation after 70, 100 and 130 mm evaporation from basin class A pan), factor B included potassium humate solution with different concentrations (0, 1% and 2% V/V) and factor C included different developmental stages (vegetative, reproductive and vegetative+reproductive stage). Results showed that drought reduced seed number in row, seed number per ear, seed weight per ear, seed length, seed weight, grain yield and harvest index. Potassium humate application increased drought tolerance. Grain yield under water deficit situation was higher than in control, but reduction by using potassium humate was lower. The highest grain yield (1539 g m(-2)) was obtained under irrigation after 100 mm evaporation and 2% potassium humate application and the least grain yield (1186 g m(-2)) was obtained without application of potassium humate. At this irrigation level without application of potassium humate, 34% reduction was observed in grain yield, but with application of 2% potassium humate only 14% percent reduction was observed. Under water deficiency, potassium humate application led to decrease of water stress effects on grain yield.