Authors : Ganesh S. Shinde
Page Nos : 136-140
Description :
The present investigation deals with the total nitrogen (%) fixed by two soil blue-green algae, Cylindrospermum musicolaand Calothrix marchicaat different concentrations of organochlorine pesticide, Endotaf. Total nitrogen fixed by studied blue-green algae at each concentration of Endotaf pesticide after 28 days of harvesting was estimated by conventional Micro-kjeldahl method. The results indicated a progressive decrease in the total nitrogen fixed by Calothrix marchicaand Cylindrospermum musicolawiththe increasing concentrations of organochlorine, Endotaf pesticide. Furthermore, Calothrix marchicawas emerged as most compatible and tolerant blue-green alga to the increasing Endotaf pesticide doses. On the other hand Cylindrospermum musicolawas foundto be highly susceptible as even at 2.5 ppm of Endotaf. At this concentration, 29.75% reduction in total nitrogen content was recorded over the untreated control in Cylindrospermum musicola. Further increase in Endotaf pesticide concentration i.e. from 250 ppm resulted into ceasing of growth and nitrogen fixation in the tested blue-green alga Cylindrospermum musicola. However nitrogen fixation of studied blue-green algae also increased at the lower doses of organochlorine pesticide, Endotaf upto 5 ppm. It was concluded that caution should be taken to determine the appropriate application dosage of these agro-pesticides before applying them into the crop fields. Since, it is essential to screen efficient blue-green algal strains those are capable of growing and fixing nitrogen at higher rate even in presence of recommended doses of the agrochemicals including pesticides, before their inoculation into the field
