Evaluation of Convolvulus arvensis For allelopathic activities

الملخص

During 2012-2013 screening of Convolvuls arvensis L weed growing in agricultural fields in Benghazi for allelopathic activity was conducted, using Radish (Raphanus sativus) for the assay of the allelochemicals. The assay experiment was carried out under laboratory conditions in the Botany Department, Faculty of Science, University of Benghazi. Several traits including percentage of seed germination (SG), seed germination index (GI), seedling vigor index (SVI), speed of germination/rate of germination (SG/RG), root and hypocotyle length (RL&HL), fresh and dry weight (FW& DW) of seedlings and percentage of growth inhibition were measured. The results showed that the aqueous extracts from dry biomass of flowers, leaves, stems and roots at 1, 5 and 10% concentrations contain growth inhibiters or stimulators substances. These substances distributed over all plant organs (flowers, leaves, stems, and roots). The effects of different extracts of plant parts were varied according to the concentration used. With inhibitory effects at high concentration and stimulatory or no effects at low concentration. The results also revealed that all extracts of different plant parts screened for allelopathic effects at 1% concentration had no significant effects on germination present (G%), germination index (GI), hypocotyle length (HL) and fresh weight (FW). Meanwhile speed germination/rate germination (SG/RG), seedling vigor index (SVI), root length (RL) and dry weight (DW) most extracts recorded stimulatory effects in comparison with controls. At 5% concentration had no significant effect of seed germination (SG) and germination index (GI). On the other hand SG/RG, SVI, RL, HL and FW was significantly reduced by most of extracts. In contrast the highest effects were recorded for all extracts of all plant parts at 10% concentration. Most traits at this concentration were significantly reduced by extracts of all plant parts. Percentage of seed germination (SG) was for leaves extract (12%) compared to controls (100%). Regarding germination index the highest effect recorded for leaves extract (0.48) compared to control (2.92). Speed/Rate of germination (SG/RG) reduced significantly by extract of C. arvensis leaves to the highest levels (3.8) compared to control (41.9). The highest inhibition of seedling vigor index (SVI), root length (RL), hypocotyle length (HL) and fresh weight (FW) however, was for Leaves extract (100 %) there was no recorded growth for radish seedlings after germination (zero). Finally the obtained results reported in this search suggest that the screened bindweed can cause grate losses in crop yield through its release of allelochemicals that can inhibit seed germination and seedling development. On the other hand allelochemicals produced by this weed may be used as natural pre- emergence herbicides to control many weeds in crop fields.