Foliar Application of Humic Acid on Plant Height in Canola

Humic acid is a principal component of humic substances, which are the major organic constituents of soil. In order to the foliar application of humic acid on plant height in canola spring cultivar (RGS-003 cul.), this experiment was conducted in 2012 at Islamic Azad University Shahr-e-Qods Branch in Tehran by a completely randomized design with four replications. The factors studied included foliar application of humic acid (Control, 0.5, 1, 1.5 and 2%) that sprayed in three stages (stem elongation, flowering stage and silique formation stage). The results showed that foliar application of humic acid significantly affected plant height and highest this parameter was achieved under 2% foliar application of humic acid and the lowest plant height was obtained under control conditions. Also, means comparison showed that plant height under 0.5% foliar application of humic acid and 1% foliar application of humic acid were in a similar statistical group. The results showed that foliar application of humic acid decreased nitrogen application in soil, that can be the most important for the non-pollution of soil by nitrogenous fertilizers.