Growth, Pigment Composition and Photochemical Characteristics of Nostoc carneum Cultured in Laboratory Condition and Treated with Insecticides

摘要

Toxicity response of two pesticides namely Monodhan and Endodhan was investigated on a photoautotrophic cyanobacterium Nostoc carneum. Monodhan treatment brought about decrease in growth, pigment and protein content, Chlorophyll-alpha (Chl alpha) fluorescence, electron transport activity compared to control at a concentration of 20 ppm whereas Endodhan caused inhibition from 5 ppm. Chl alpha fluorescence emission ratio (F_(685)/F_(735)) of the organism gradually increased from 20 ppm to 100 ppm of Monodhan and 5 ppm to 15 ppm of Endodhan treatment compared to the control whereas, fluorescence excitation ratio gradually declined as the concentration of the pesticides increased. High polarization values were observed in 100 ppm of Monodhan and 15 ppmof Endodhan. Malondialdehyde accumulation gradually increased compared to the control with the increase in pesticide concentration. Loss in the rate of electron transport in terms of 2,6-dichlorophenolindophenol photoreduction was also noted in the pesticide-treated samples. The results show a differential response on pigment and protein content and photochemical characteristics of N. carneum towards the two pesticides used for their toxicity study.