Phytochemicals and vam for management of nematodes in brinjal

Abstract

Aqueous neem leaf extract, neem oil and marotti oil at different concentrations were tested as bare root-dip treatments for their efficacy in containing root-knot nematode infestation in brinjal. Root-dip in neem leaf extract for one hour resulted in significantly better height and number of leaves in the treated plants than nee m oil and marotti oil. Among the different concentrations of neem leaf extract tested, 6.25 and 25 per cent extracts proved more effective. Significant reduction in gall index was also seen in neem leaf extract treated plants. Higher concentrations of the extract (50 and 25 per cent) significantly reduced the number of egg masses produced. But none of the phytochemicals had any adverse effect on the hatching of the egg masses. All the three phytochemicals irrespective of the doses reduced population of the nematode in the soil. An overall assessment of the result established the superiority of neem leaf extract (25 per cent) among the different phytochemicals tested in checking nematode infestation. Different isolates of V AM fungi like, G. fasciculatum, G. etunicatum, G. mosseae, G. constrictum G. monosporum and A. morroweae did not show any significant difference in the growth parameters of brinjal plants (height and number of leaves) at transplanting and one month after transplanting irrespective

of the pot size. Later (45 and 60 days after transplanting) significant increase in height and number of leaves were observed in plants raised in soil inoculated with G.etunicatum and G. fasciculatum. Higher percentage of V A mycorrhizal colonisation was observed in plants artificially inoculated with V AM. Plants raised in G. etunicatum G. fasciculatum and G. monosporum recorded significantly lower root-knot indices. The fecundity of the nematode and the number of larvae hatching per eggmass was also significantly reduced in mycorrhizae treated plants. Irrespective of the pot size, G.fasciculatum registered the lowest population per gram root while G. fasciculatum and G. constrictum significantly lowered the nematode population in the soil. Overall assessment of the results revealed G. fasciculatum as the most effective mycorrhizae among the isolates tested for protecting brinjal plants from root-knot infestation. Field trial with bare-root dip in 25 per cent neem leaf extract and insecticides monocrotophos (500 and 250 ppm) and carbosulfan (500 and 250 ppm) nursery treatment with G. fasciculatum and root-dip of the mycorrhizal seedlings in neem leaf extract and nematicides did not show any significant effect on growth parameters of the plant like height, number of leaves and root weight But the . bare-root dip treatment in neem leaf extract and mycorrhizal nursery treatment and bare-root dip treatment in monocrotophos 500 ppm resulted in significant increase in shoot weight.

Root-dip in nematicides was definitely superior to root- dip in neem leaf extract and nursery treatment with G. fasciculatum in increasing yield significantly. Bare-root dip in neem leaf extract, nursery treatment with G.fasciculatum also registered significantly higher yield. Root-dip of mycorrhizal seedlings in monocrotophos and carbosulfan were far more superior than the individual treatments in increasing the yield of brinjal. During the early stage (45 DAT) no significant difference was seen in the gall index, number of egg mass per plant and mycorrhizal colonization percentage. Later, as the plant matured a significant difference was seen in these parameters. Root -dip in neither nematicide nor neem leaf extract showed any deleterious effect on mycorrhizal colonisation.