Effect of herbicides on population dyanamics of soil borne microorganisms in cotton

An experiment was conducted to study the effect of herbicides on population of soil borne microorganism from the rhizosphere of cotton during 2014–15 at Department of Plant Pathology and field of All India Co-ordinated Research Project on Integrated Weed Management in Cotton, Dr. PDKV, Akola. The soil samples were collected before application of herbicides and at 15^th, 30^th and 45th days after sowing from the cottonrhizosphere and microbial populations estimated. Application of herbicides was reduced the soil borne population of bacteria, fungi and actinomycetes for rhizosphere in cotton. The application of Pendimethalin followed by 2 HW (T₁) recorded the highest population of bacteria (59.55, 61.33, 49.77×10⁷cfu/g soil). The Pendimethalin followed by Glyphosate directed spray (T₈) recorded the highest population of soil borne fungi (12.11, 9.33, 9.55×10⁴cfu/g soil) whereas application of Pyrithiobac-sodium+Quizalofop-p-ethyl (T⁴) recorded the highest population of actinomycetes (10.88, 9.67, 8.55×10⁵ cfu/g soil) which was a safer treatment at 15^th, 30^th and 45^th DAS. Among the treatments tested, weedy check (T₁₀) was recorded the highest population of soil borne microorganisms (bacteria, fungi and actinomycetes) in cotton crop.