Phytotoxic effect of organophosphate insecticides; phosphomidon and monocrotophos on wheat, maize and mustard

Abdullah and Masood Akhtar

Department of Botany, Shibli National P. G. College Azamgarh - 276 001 India.

ABSTRACT: Wheat, maize and mustard were selected to observe the phytotoxic effect of two important organophosphate insecticides; phosphomidon and monocrotophos. The experiment was divided into two parts. In first part, seed germination experiment was carried out in which parameters related to seed germination were recorded. In second part pot culture experiment was done where plants were grown in polythene bags containing same soil and parameters related to growth and development were recorded on 30th day after sowing the seeds. The effect of both insecticides on seed germination percentage on wheat, maize and mustard showed a gradual decrease at increasing concentration. However, the lower concentration of monocrotophos slightly induces the germination. The delay in seed germination was also pronounced as evident by sprouting time. As concentration increased there was delay in germination time. Mean rootlet length and shootlet length were badly affected by the increasing concentration of both insecticides. The Seedling Vigour Index (SVI) of rootlets and shootlets indicates the decrease in vigourness as increasing concentration of both insecticides. Vigourness slightly increased with lower concentration of monocrotophos. In pot culture experiment, shoot length growth was decreased as the concentration of both insecticides increased. In mustard lower concentration of monocrotophos promotes the growth over control. There were reduction in leaf area of wheat, maize and mustard, but lower concentration of monocrotophos promotes the leaf area of mustard. Number of leaf was also decreased as concentration increased in all three plants and for both insecticides. The chlorophyll contents were decreased at increasing concentration of both insecticides. The phenomenon of chlorosis and necrosis were also observed, which starts from margins of the leaves and later leaves become whitish and dry.

KEYWORDS: Phytotoxicity; phosphomidon; monocrotophos; wheat; maize; mustard

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