442 Impact of different herbicides and their combinations on production economics of winter rice in West Bengal S.K. Sarkar*, B.C. Patra, K. Jana and K. Ghosh Department of Agronomy, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, West Bengal 741 235 Received: 24 November 2016; Revised: 23 December 2016 Key words: B:C ratio, Chemical control, Economics, Hand weeding, Winter rice, Weed management Rice is the life-blood of the Asia-Pacific Region where 56% of humanity lives, producing and consuming more than 90% of the world rice. Rice contributes 43% of total food grain production and 46% of the cereal production of India. Rice is the staple food of about 3.5 billion people and demand is expected to continue to grow as population increases (GRiSP 2013). Among different states of India, West Bengal is the leading state in rice production. During the year 2007-08, the average productivity of Aus, Aman and Boro was 2009 kg/ha, 2.31 t/ha and 3.26 t/ ha, respectively and the state average of rice productivity was 2.57 t/ha (Samanta and Mallik 2004). Weeds are greatest constraint in rice crop and impose a serious negative effect on crop production and market value. On an average, farmers lose 37% of their rice yield to pests and diseases, and that these losses can range between 24% and 41% depending on the production situation (IRRI 2015). Herbicides are being widely looked as an alternatve of manual labour. Hence, different herbicides were tested to see their effect on economics of rice production. The field experiment was conducted at the Instructional Farm of Bidhan Chandra Krishi Viswavidyalaya, new alluvial zone (NAZ) of West Bengal under the sub-tropical humid climate during Kharif Season (July to November) of 2015 on soil with medium fertility status, having sandy loam in texture (pH- 6.7). The experiment was laid out at randomized block design (RBD) having thirteen treatments, viz. butachlor 1.5 kg/ha (granules) as pre- emergence (PE) at 2 days after transplanting (DAT) with one hand weeding (40 DAT), pyrazosulfuron- ethyl 25 g/ha as PE (2 DAT) with one hand weeding (40 DAT), bensulfuron-methyl + pretilachlor 10 kg (granules)/ha as PE (2 DAT) with one hand weeding (40 DAT), bispyribac-sodium 10% SC 25 g/ha as post-emergence (POE) at 20 days after transplanting (DAT), metsulfuron-methyl + chlorimuron-ethyl 4 g/ ha as POE (20 DAT), butachlor (PE - 2 DAT) + bispyribac-sodium (POE – 20 DAT), pyrazosulfuron- ethyl (PE - 2 DAT) + bispyribac-sodium (POE – 20 DAT), (bensulfuron-methyl + pretilachlor ) as PE (2 DAT) + bispyribac-sodium (POE - 20 DAT), butachlor (PE - 2DAT) + (metsulfuron-methyl + chlorimuron-ethyl as POE (20 DAT)), pyrazosulfuron-ethyl (PE-2 DAT) + (metsulfuron- methyl + chlorimuron-ethyl as POE (20 DAT)), (bensulfuron-methyl 0.6% + pretilachlor as PE - 2 DAT) + (metsulfuron-methyl + chlorimuron-ethyl as POE (20 DAT)), two hand weeding at 20 and 40 DAT, weedy check, replicated thrice. Herbicides were sprayed using knapsack sprayer fitted with a flat fan nozzle at a spray volume of 500 l/ha except the granular herbicides, which were applied by mixing with sand 50 kg/ha. The variety ‘ Swarna (MTU- 7029) ’ was grown with recommended package of practices followed uniformly. The observations on yield and yield attributes like grain yield, straw yield, no. of panicles/m 2 , filled grains/panicle and 1000-seeds weight were recorded at harvest. Weed and crop biomass at different growth stages of rice, weed index and economics were worked out. All the collected data was analyzed statistically to the design RBD by following the procedure laid out by Gomez and Gomez (1984). The observations revealed that the predominant weed species were Cynodon dactylon , Leersia hexandra , Echinochloa colona , Commelina benghalensis , Brachiaria mutica , Echinochloa Crusgalli, Cyperus rotundus, Cyperus difformis, Fimbristylis dichotoma, Scirpus validus, Ammannia baccifera , Ageratum haustonianum, Spilanthus paniculata, Marsilea quadrifolia, Scoparia dulcis, Sphenoclea zeylenica , Xanthium strumarium , Ludwigia parviflora, Ipomoea reptens, Lindernia ciliata, and Nymphoides indica. Effect on rice biomass Dry matter accumulation increased progres- sively from 30 to 60 DAT. But, variations were observed in different treatments. The better weed control made the availability of soil moisture, *Corresponding author: sandiptakumarsarkar16@gmail.com Indian Journal of Weed Science 48(4): 442–444, 2016 DOI: 10.5958/0974-8164.2016.00113.1 Short communication