Allelopathic response of Phalaris minor to crop and weed plants in rice-wheat system

Green manuring of sunflower and dhaincha reduced plant population of Phalaris minor 100 per cent under lab and 42 per cent and 15 per cent, respectively, under field conditions, thus, indicating the inhibitory role of allelo-chemicals. Grain yield of wheat was significantly higher with the green manuring of sunflower and dhaincha before rice transplanting over summer fallow. The allelopathic potential of broad-leaved weeds of wheat in inhibiting germination of P. minor was in the order of Chenopodium album = Medicago denticulata = Melilotus indica = Convolvulus arvensis (100 per cent inhibition) > Vicia hirsuta (86 per cent) > Cirsium arvense (48 per cent) > Lathyrus aphaca (38 per cent) > Rumex acetosella (9 per cent). Exudates of rice cultivars HKR 126, IR 64, Jaya and Haryana Basmati-1 registered > 50 per cent inhibition of germination of P. minor. As the extract was diluted, effect of non-scented cultivars considerably reduced in comparison to scented group. Out of I I wheat varieties, WH533 provided the highest inhibition of germination (30 per cent) followed by WH542 (21 per cent). (C) 2002 Published by Elsevier Science Ltd.