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Distribution of Alkaloides and Allelopathism of Selelected Weeds from a Post Harvest Crop Field

Parimita Purohit, Rosina Rosalin

Though beneficial the weeds always pose an important biological constraint to crop productivity. The economic losses that are caused by these weeds globally costs billions of rupees every year. Allelopathic potentialities of plants are considered as an alternative natural way of weed management strategy for crop production as well as environmental benefits.Although the plants like the weeds are the great reservoirs of many new & potential phytochemicals,majority of them still remains unexplored either due to restricted habitat or because of being wild in nature.Hence the present survey was carried out taking ten (10) selected weeds of various stages of development from post harvest crop fields of Rice and Mustard in the OUAT Farm campus which have been left open for around two months. The Botanical authentication of the weeds were done by following the Texonomic literatures.They are Cardus nutans L, Cerastium fontanum Baumg., Cleome viscosa L., Euphorbia maculata L. ,Helianthus tuberosus L., Lactuca serriola L., Phyllanthus niruri L. ,Sinapsis arvensis L. ,Vernonia cinerea Scherb., Veronica arvensis L.Weeds were collected between January and February 2014 . Their crude alkaloidal contents were extracted and estimated from the dried powder of the whole plant following the standard methods (Harborne et al 1992). All plant samples indicate the presence of good amount of Alkaloid, highest being in Veronica persica Poiret.(17.35%) and lowest in Cardus nutans (3.07%). Variation of alkaloidal contents with variation in stage of development maximum reaching at the flowering stage, was indicated within the individuals of the same family. The quantity of the alkaloid was species specific.The allelopathic effect of the crude alkaloidal extract tested against the seed germination of Rice,Mung(Green gram ) and Mustard , indicates that the alkaloids are not so effective towards the growth of Rice but quite inhibitory towards the growth of Mung.This result is interpreted basing upon their chi-scquare values.