Growth, chlorophyll a content, nitrogen-fixing ability, and certain metabolic activities ofNostoc muscorum: Effect of methylparathion and benthiocarb

Effects of the Herbicide Molinate on Mixotrophic Growth, Photosynthetic Pigments, and Protein Content ofAnabaena sphaericaunder Different Light Conditions

“…It was found that benthiocarb at concentrations ranging from 6 to 8 g ml −1 was lethal to some species of Nostoc (Bhunia et al, 1991;Mishra and Pandey, 1989), and the IC 50 for butylate to Selenastrum capricornutum was 6.47 g ml −1 (Caux et al, 1996). The present studies with molinate indicate that A. sphaerica maintains a definite growth rate, even at concentrations up to 50 g ml −1 , which is much higher than the lethal doses of the above-mentioned carbamate pesticides.…”

“…Most reports demonstrate that the inhibitory effect of herbicide increased with an increase in herbicide concentration, and suggested that the reduction in the growth rate of algae may be due to a decrease in algal photosynthesis caused by the inhibition of synthesis of chlorophyll a, the most important pigment in algal cells for collecting solar energy for photosynthesis (Pandey, 1985;Abou-Waly et al, 1991). As for the effects of the carbamate herbicide, Bhunia et al (1991) reported that the chlorophyll a content of N. muscorum was reduced by 56, 74, and 97% at 2, 4, and 6 g ml −1 benthiocarb, respectively, and suggested that the low pigment content may be caused by photooxidation arising from the inability of chlorophyll a to dissipate its absorbed excitation energy when electron transport is inhibited. The results in the present study indicate the dose dependence of molinate toxicity on chlorophyll a synthesis was opposite that on growth during the early days of the experimental period, particularly under 3000-lux light, demonstrating that chlorophyll a content increased as the concentration of molinate increased.…”

“…Soil algae, particularly nitrogen-fixing cyanobacteria, are important photosynthetic microorganisms because they contribute to soil fertility by fixing the atmospheric nitrogen (Watanabe, 1962) and are also quite sensitive to herbicides because they share characteristics with higher plants (ElSheekh et al, 1994). Many reports available indicate interaction between soil algae and herbicides, including effects of herbicides on algal growth, photosynthesis, nitrogen fixation, biochemical composition, and metabolic activities (Bhunia et al, 1991;Singh and Tiwari, 1988;El-Sheekh et al, 1994;Mishra and Pandey, 1989;Caux et al, 1996;Mattoo et al, 1984), as well as degradation and removal of herbicides by algae (Stratton, 1984). These studies, however, were conducted under standard phytotoxicity test conditions involving only the results of photoautotrophic growth of algae.…”

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“…galeata. 9 Benthiocarb can decrease the growth of Nostoc muscorum 10 and carbofuran can also decrease the growth of S. quadricauda, Microcystis aeruginosa, L. minor, 5 Anabaena fertilissima and Nostoc commune. 11 Furthermore, dimetilan decreases the fresh weight and dry weight of P. sativum and V. sinensis.…”

A Field Guide to Biological Soil Crusts of Western U.S. DrylandsA Field Guide to Biological Soil Crusts of Western U.S. Drylands

“…Exposure to crude oil and oil dispersants decreases nitrogen fixation in Nostoc (Marowitch et al 1988). Nitrogen fixation is significantly inhibited in Nostoc by many insecticides, herbicides, and phenolic compounds tested (Bhunia et al 1991;Megharaj et al 1988).…”