THE EFFECTS OF SELECTED HERBICIDES ON ZYGOSPORE GERMINATION AND GROWTH OF CHLAMYDOMONAS MOEWUSII (CHLOROPHYCEAE, VOLVOCALES)¹¹

Abstract

A laboratory study was conducted, to examine and compare the sensitivity of vegetative cells and zygospores of Chlamydomonas moewusii Gerloff to 20 different herbicides. Under the culture conditions employed, both vegetative growth and zygospore germination were affected by certain herbicides and not by others. Over a concentration range from 1.0–80.0 μM, growth was inhibited to various degrees by herbicides containing ametryne, paraquat, endothall, diquat, diuron, linuron, propanil, dinoseb, ioxynil, atrzine, prometon, and alachlor. Zygospore germination was inhibited significantly by herbicides containing dinoseb, endothall, parquet, diquat, propanil, linuron, ioxynil, ametryne, fenac and picloram at 80.0 μM concentrations. Comparisons of the results obtained indicate that concentrations of herbicides which affect growth may or may not effect zygospore germination and vice versa. Zygospores may be more resistant than vegetative cells to some but not all herbicides.

Pesticide Effects on Soil Algae and Cyanobacteria

“…In addition to the studies on vegetative cells of Anabaena doliolurn, Kashyap and Pandey (1982) also examined the response of spores of this cyanobacterium to butachlor; the spores were found to be approximately four times more resistant than vegetative cells. Very few workers have considered the possibility of tolerance differences between vegetative cells and resting stages (Cain and Cain 1983). In a later study, Anabaena doliolurn was found to be more tolerant than either Nostoc rnuscorurn or Anacystis nidulans to butachlor, lethal concentrations being 20, 5, and 2.5 ppm, respectively (Pandey and Kashyap 1986).…”

“…Others (ametryne, dinoseb, diquat, endothall, ioxynil, linuron, paraquat, and propanil) inhibited to some extent both vegetative growth and zygospore germination. Diuron, atrazine, alachlor, and prometon inhibited only vegetative growth, whereas fenac and picloram inhibited only zygospore germination (Cain and Cain 1983). The authors concluded that zygospores may be more resistant than vegetative cells to some but not all herbicides.…”

“…In two articles (Metting and Rayburn 1979;Plumley and Davis 1980), members of the Chrysophyta were also examined. The herbicides tested encompass a wide variety of different groups, many of them (alachlor, ametryne, amitrole, atrazine, bromoxynil, chloramben, chlorfenac, dalapon, dicamba, dinoseb, diquat, diuron, endothall, ioxynil, linuron, paraquat, picloram, prometon, propanil, and 2,4-D) examined in a single study (Cain and Cain 1983). This study is important since it constitutes an investigation of the comparative sensitivity of algal vegetative cells and zygospores, a topic that has been infrequently addressed.…”

“…This study is important since it constitutes an investigation of the comparative sensitivity of algal vegetative cells and zygospores, a topic that has been infrequently addressed. The test organism was Chlamydomonas moewusii, commonly occurring in both freshwater and soil habitats (Cain and Cain 1983). Using herbicide concentrations ranging from 1-80 f1M,2 Cain and Cain (1983) noted that some herbicides (amitrole, bromoxynil, chloramben, 2,4-0, dalapon, and dicamba) inhibited neither the growth of vegetative cells nor germination of zygospores.…”

“…The test organism was Chlamydomonas moewusii, commonly occurring in both freshwater and soil habitats (Cain and Cain 1983). Using herbicide concentrations ranging from 1-80 f1M,2 Cain and Cain (1983) noted that some herbicides (amitrole, bromoxynil, chloramben, 2,4-0, dalapon, and dicamba) inhibited neither the growth of vegetative cells nor germination of zygospores. Others (ametryne, dinoseb, diquat, endothall, ioxynil, linuron, paraquat, and propanil) inhibited to some extent both vegetative growth and zygospore germination.…”