Effects of sunflower (Helianthus annuus L.) allelochemicals on soyabean (Glycine max L.) germination, seedling growth and their identification

All the experiments related to this research project were conducted in the laboratory of Chemistry Department and Department of Agronomy, University of Agriculture, Faisalabad, at Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad. The objectives were: a). To study the effects of various concentrations of sunflower (Helianthus annuus L.) water extract (SWE) on the germination, growth and chemical constituents of soyabean (Glycine max L.) seedlings. b). To identify allelochemicals in sunflower by thin layer chromatography (TLC) and paper chromatography (PC). The results of four concentrations of sunflower water extract (SWE) i.e. 25, 50, 75 and 100% when applied on soyabean seeds indicated that an increase on seed germination percentage was found in 25 and 50% concentrations in comparison to 75 and 100% concentrations which were less than the control. Maximum germination was found at 25% concentration, which was 21.7% greater than control. The mean shoot length of soyabean seedlings was more in 25 and 50% concentrations than the control whereas mean shoot length of seedlings was found lesser in 75 and 100% concentrations in comparison to control. The mean fresh weight and dry weight of seedlings was found more than control in 25 and 50% concentrations of SWE whereas 75 and 100% concentrations showed lesser than control. It was concluded that lower concentrations i.e. 25 and 50% of sunflower water extract showed stimulatory effects whereas higher concentrations i.e. 75 and 100% were inhibitory to the germination and growth of soyabean seedlings. The chemical analysis of soyabean seedlings for their starch, potassium, phosphorus, protein and ash contents indicated that starch, protein, potassium and ash contents increased in all treatments in comparison to the control whereas in case of phosphorus the maximum phosphorus contents were found in 25% concentration while in 50 and 100% concentrations reduction has been found as compared to the control. This showed the inhibitory and stimulatory effects of allelochemicals present in sunflower water extract to the soyabean seedlings quality. After studying the effects of sunflower water extract on the growth and quality of soybean seedlings, it was interesting to identify those compounds (allelochemicals). Therefore, thin layer chromatographic (TLC) and paper chromatographic (PC) techniques were conducted. Thin layer chromatography (TLC) showed better resolution of the compounds than the paper chromatography (PC). Chlorogenic acid, caffeic acid, ferulic acid, vanillic acid and syringic acid have been identified when sunflower plant (stein and leaves) extract was separated in TLC system using n-pentane, diethylether and acetic acid a developing system and folin reagent as chromogenic reagent.