Effect of Secondary Metabolites in the Root Growth of Arabidopsis thaliana

Green manure has usually great benefits for the yield of successive crops. It also increases the organic matter and structure of the soil, lessens erosion and in some cases it decreases the nitrogen leaching (Jung et al. 1990). The use of legumes as green manure has additional benefits due to their ability to fix nitrogen in the soil via roots as well as to support the growth of mycorrhizal fungi (Peoples, 2009).

Faba bean (Vicia faba L.) green manure is rich in secondary compounds, especially phenolic compounds. Among these compounds coumarin, p-coumaric acid, ferulic acid, fumaric acid, gallic acid, hydrocinnamic acid, p-hydroxybenzoic acid, juglone, and pyrocatechol are recorded as weed inhibitors (Williams & Hoagland, 1999).

The aim of this research was to test the effect of the faba bean shoot water extracts mimicking the green manure on the root development of Arabidopsis thaliana L. (Col-0). The test was done in four replicates, using four different doses of the extracts. The primary and secondary root development was analyzed by classical bioassays. The measurements included daily root elongation, amount of lateral roots and cambium development.

The results showed significant differences (P< 0.05) in the length of the primary roots of the treated plants versus control. Additionally, it was observed root necrosis and malformation of the cambium and the meta- and protophloem. These results reveals that the extracts from faba bean shoots have a potential effect in the physiology and morphology of dicotyledonous plants. Suggesting that the secondary metabolites of faba bean could be utilized as a tool in weed management with carefully planned cropping sequences or rotations. Yet, further research is needed to test the effect of faba bean green manure in field conditions.