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Screening and selection of most potent diazotrophic cyanobacterial isolate exhibiting natural tolerance to rice field herbicides for exploitation as biofertilizer
Author(s) -
Singh Surendra,
Datta Pallavi
Publication year - 2006
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.200510074
Subject(s) - biofertilizer , diazotroph , cyanobacteria , biology , nostoc , anabaena variabilis , botany , chlorophyll , paddy field , photosynthesis , nitrogen fixation , anabaena , horticulture , agronomy , bacteria , genetics
Abstract Periodic applications of heavy dosages of herbicides in modern rice‐agriculture are a necessary evil for obtaining high crop productivity. Such herbicides are not only detrimental to weeds but biofertilizer strains of diazotrophic cyanobacteria also. It is therefore, essential to screen and select such biofertilizer strains of diazotrophic cyanobacteria exhibiting natural tolerance to common rice‐field herbicides that can be further improved by mutational techniques to make biofertilizer technology a viable one. Therefore, efforts have been made to screen five dominant diazotrophic cyanobacterial forms e.g. filamentous heterocystous Nostoc punctiforme , Nostoc calcicola , Anabaena variabilis and unicellular Gloeocapsa sp. and Aphanocapsa sp. along with standard laboratory strain Nostoc muscorum ISU against increasing concentrations (0–100 mg l –1 ) of four commercial grade common rice‐field herbicides i.e. Arozin, Butachlor, Alachlor and 2,4‐D under diazotrophic growth conditions. The lethal and IGC 50 concentrations for all four herbicides tested were found highest for A. variabilis as compared to other test cyanobacteria. The lowest reduction in chlorophyll a content, photosynthetic oxygen evolution, and N 2 ‐fixation was found in A. variabilis as compared to other rice field isolates and standard laboratory strain N. muscorum ISU. On the basis of prolong survival potential and lowest reductions in vital metabolic activities tested at IGC 50 concentration of four herbicides, it is concluded that A. variabilis is the most potent and promising cyanobacterial isolate as compared with other forms. This could be further improved by mutational techniques for exploitation as most potential and viable biofertilizer strain. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)