Effect of root exuded allelochemicals of sorghum (Sorghum bicolor) on growth and development of purple nutsedge (Cyperus rotundus L.) and other weeds of pulses

Laboratory experiments were conducted during 2006–09 at IIPR, Kanpur, Uttar Pradesh to find out the effect of allelochemicals released via roots of sorghum as exudates against purple nutsedge (Cyperus rotundus L) and other weeds of winter pulse crops. Emulsifiable concentrate (EC) formulation developed from the isolated exudates, caused severe reduction in vegetative growth, root biomass and tuber regeneration. The formulation (400 μg/g of soil) caused 70–75% reduction in shoot biomass and total biomass of the weed, and 80% reduction in average biomass of roots and their tuber regeneration tendency. The vegetative growth of lambsquarters (Chenopodium album, L.), scarlet pimpernel (Anagalis arvensis, L.), corn flurry (Spergula arvensis, L.), common vetch (Vicia sativa, L.) and white sweet clover (Melilotus alba, L. Medik.) was also reduced. The formulation was more toxic to V. sativa by inhibiting total biomass by 67.26% followed by C. album (62.59%), M. alba (51.52%), S. arvensis (50.82%) and A. arvensis (26.21%).