Abstract

In vitro and in vivo bio-stimulatory activity of a Lupinus albus cv. Bethuana white Seed Suspension (SS) was previously documented using vegetable crops. This was repeated for two grain crops, maize and wheat, in an attempt to provide a rationale forthe isolation and identification of the active compound(s) involved. In all cases, besides negative controls, the response to treatment with SS was compared to that of a commercial bio-stimulant, ComCat^®. At an optimum concentration of 5 mg â„“^-1 SS significantly enhanced seedling growth and yield in both crops. Subsequently, activity directed liquid-liquid extraction of ground L. albus seed resulted in an ethyl acetate extract containing most of the bio-stimulatory activity. Two in vitro bio-assay procedures were employed to appraise the in vitro bio-stimulatory properties of semi-purified fractions as well as pure compounds contained in it. The highly active ethyl acetate extract was fractionated further by means of adsorption column chromatography resulting in eighty five fractions that were combined into twelve on the basis of similarities in thin layer chromatography profiles. Four of these fractions showed significant bio-stimulatory activity and were pooled. From this one compound was isolated, purified and identified as glyceryl trilinoleate by means of nuclear magnetic resonance spectroscopy.

Key words: Lupinus albus, seed suspension, field trials, yield, NMR spectroscopy, glyceryl trilinoleate.