Abstract
The allelopathic impact of aqueous extract of 2 weeds Malva parviflora and Chenopodium murale on growth and photosynthesis of barley was investigated. The barley plants were sown in plastic pots containing a compost: sand mixture and placed in growth chambers. Plants were treated with the following weed aqueous extract concentrations; 0%, 25%, 50%, 75% and 100%. Different responses of plants to the two weeds were observed. Plant heights, number of leaves, number of tillers, root dry weight were not affected by M. parviflora. A clear effect of C. murale was recorded on the growth parameters; plant height, number of leaves and number of tillers, root fresh and dry weight. M. parviflora affected leaf growth, measured as leaf fresh weight (LFW), leaf dry weight (LDW) and leaf area. All the growth parameters measured were more adversely affected by C. murale than by M. parviflora. Significant effect at 25% and 50% and highly significant effect at 75% and 100% were recorded. The only concentration of M. parviflora that affected chlorophyll content was 100%, while the effect of C. murale was significant at 50% and highly significant at 75% and 100%. Photosynthesis was also inhibited by the two weeds, with more effect being with C. murale compared with M. parviflora