WEED SUPPRESSION IN MAIZE (ZEA MAYS L.) THROUGH THE ALLELOPATHIC EFFECTS OF SORGHUM [SORGHUM BICOLOR (L.) CONARD MOENCH.] SUNFLOWER (HELIANTHUS ANNUUS L.) AND PARTHENIUM (PARTHENIUM HYSTEROPHORUS L.) PLANTS

The present study was carried out at the Weed Science Research Laboratory, The University of Agriculture, Peshawar Pakistan (June-July 2013 and Sep-Oct 2013). To evaluate the most effective and economical treatment for weed management in maize (Zea mays L.), the pot experiment was performed using completely randomized design (CRD) with three replications. Allelopathic effects of Sorghum bicolor (L.) Conard Moench., Helianthus annuus L., Parthenium hysterophorus L, and the commercial herbicide (atrazine @ 18 g L-1) was used for comparison. The data were recorded on germination and seedling growth of test species (Zea mays, Trianthema portulacastrum and Lolium rigidum). The data showed that S. bicolor + H. annuus + P. hysterophorus water extract (WE) @ 33.33 + 33.33 + 33.33 (g L-1) reduced dry biomass of T. portulacastrum and L. rigidum by 35 and 41% respectively, whereas the commercial herbicide by 45-47%. Maize seeds were found more tolerant than the weed species tested. Hence, it is concluded that extracts applied in mutual combination had more inhibitory effect than their sole applications, however, the efficacy of atrazine was more effective in suppressing germination and seedling growth of the tested species. The degree of toxicity for the various treatments can be placed in the following array of inhibition: Herbicide > combined extracts > isolated extracts. The current study showed that all the tested allelopathic plants contain water soluble allelochemicals which could inhibit/retard the germination percentage and seedling growth of the tested species. Hence, the findings of the current study suggest that it is possible to use these extracts as an alternative to synthetic herbicide (s) for sustainable weed management in maize. However, further studies are suggested to confirm our findings under field conditions.