Abstract
Root exudates of marigold ((Tagetes erecta), collected from intact live plants via newly developed root exudates trapping system after proper fractionation gives rise to a total of five allelofractions viz., C, B, A, E and D of different polarity (non-polar to polar). The obtained fractions were found enriched with one single compound in each of them. Two Emulsifiable Concentrate (EC) from non-polar fraction (A&B) and one from medium polar fraction viz., C) developed from 90% pure fractions, clearly revealed the role of polarity, exposure time and the concentration of isolated fractions in imparting their toxicity against second stage juveniles (J2) of Meloidogyne javanica in laboratory experiment. EC formulations of fractions A and B (soluble in Hexane & ethyl acetate) was found 100 % toxic to the juveniles at 200 ?g ml -1 of concentrations after an incubation period of 24 h whereas, EC formulation developed from fractions C (acetone soluble) showed nearly 70 % juvenile mortality at 700 ?g ml -1 concentrations, at an incubation period of 72 h. The EW formulation of fraction D &E (polar) could not observe to produce any mortality in juveniles in all their test concentrations ranged from 800-1200 ?g ml -1 hence not utilized for nematode control. Non-polar fraction based EC formulations (A &B) at their higher concentrations of 150 & 200 ?æg ml -1 , were not only found extremely effective in juvenile mortality but also retarded egg hatch of the test nematode up to an extent of more than 98 %. At higher oncentrations, the said formulations were also observed to cause permanent damage to the exposed eggs as there was no further hatching noticed when treated egg masses were kept in ordinary water for their revivals. As compare to control, the most active EC formulations of non-polar and medium polar fractions viz., A, B & C in pot experiments conducted to control nematode infestation in brinjal and chilli were found to reduce 30-40% and 20-30% gall formation respectively. Apart from gall control the formulations were also found capable in crop bust and yield gain. In case of brinjal more than 100% yield gain was observed in some of the treatments whereas, in case of chilli nearly 40% yield gain was observed.
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