Effect of planting date and salicylic acid spray on growth of burdock plant (Arctium lappa L.) and its roots content of quercetin and arctiin compounds

Abstract

This experiment was conducted at the Experimental Research Station, Agric. College, Baghdad, during 2015-2016, growing to study the effect of three planting dates (15/9, 15/10 and 15/11) as a main plots, and three foliar spray rates of salicylic acid (50,100 and 200) mg..l-1 in addition to control, on growth of burdock plants (Arctium lappa L.) and their content of quercetin and arctiin compounds . The results of study showed that plants of the first planting date (15/9) significantly increased plant height , leaf area, dry weight of vegetative growth, dry weight of roots and content of arctiin (0.410 mg.plant-1 dry wt.) , as compared to other planting dates. Third planting date (15/11) significantly exceeded others in roots content of quercetin (6.428 mg.plant-1 dry wt.). 100mg.l-1 salicylic acid gave the highest plant height, leaf area, dry weight of vegetative growth and dry weight of roots, and on roots content of quercetin (6.366 mg.plant-1 dry wt.),however, 200mg.l-1 gave the highest value of arctiin (0.432 mg.plant-1 dry wt. Dual interaction showed sinificancies only in root contents of quercetin and arctiin