Dry direct-seeded rice

Energy budget

Rice herbicides

Weed management practices

A field experiment was conducted at Main Research Station, Hebbal, Bengaluru during Kharif 2016 and Kharif 2017 to study the effect of different herbicide combinations and weed management methods on yield, energetics and economics of dry direct-seeded rice. The experiment consisted of 12 treatments and replicated thrice in RCBD design. Among various weed management treatments hand weeding at 20, 40 and 60 DAS recorded significantly highest paddy grain and straw yield in hand weeding at 20, 40 and 60 DAS (5.50 and 7.22 t/ha, respectively) and found at par with application of bensulfuron-methyl + pretilachlor as pre-emergence fb bispyribac-sodium (5.39  and 7.16 t/ha, respectively). Weedy check recorded significantly lowest yield (1.40 and 2.32 t/ha, respectively). Among the various herbicide combinations, sequential application of bensulfuron-methyl + pretilachlor as pre-emergence fb bispyribac-sodium was found to be the most energy and economically efficient weed management strategy in dry direct-seeded rice and had maximum value of total output energy (169090 MJ/ha), net energy returns (157444 MJ/ha), energy use efficiency (14.52), net returns (` 59,276/ha) and benefit cost ratio (2.93).

Direct-seeded rice

Weed control efficiency

Weeds dry weight

An experiment was conducted during Kharif 2016 and 2017 at Agricultural Research Station, Dhadesugur, University of Agricultural Sciences, Raichur, Karnataka, India, to study the bio-efficacy of weed control practices on weeds and grain yield of dry-seeded rice. The dominant grassy weeds in fields were Echinochloa sp. Panicum repens, Cynodon dactylon, Bracharia mutica, Digitarias sanguinalis, Commelina communis and Leptochloa chinensis. Broad-leaf weeds were Eclipta alba, and Ludwigia parviflora and Cyperus sp. as sedge. Results revealed that, pre-emergence application of pretilachlor + pyrazosulfuron-ethyl (600 + 15 g/ha) recorded significantly lower weed dry weight at 15, 30 and 45 DAS during Kharif 2016 and 2017, higher weed control efficiency at 15, 30 and 45 days after sowing (DAS) (82.6, 80.2 and 80.6% during Kharif 2016 and 82.1, 82.7 and 80.2%, respectively during Kharif 2017, respectively) and higher rice grain yield (4.92 and 4.98 t/ha during Kharif 2016 and 2017, respectively) and which was at a par with twice hand weeding at 20 and 40 DAS.

Cropping system

Penoxsulam 

Residual effects 

Rice-wheat 

Transplanted rice

Weed complex 

Field experiments were conducted to evaluate the bio-efficacy of penoxsulam 2.67% w/w (2.5% w/v) OD applied as post-emergence (PoE) in transplanted rice and its residual effect in succeeding wheat crop at CCS Haryana Agricultural University, Regional Research Station, Karnal. Penoxsulam 22.5 g/ha reduced the density (0.0 to 0.7/m2) and dry weight (0.0 to 6.3 g/m2) of grassy weeds during 2011 and 2012 and was similar to weed free check. Penoxsulam at 22.5 g/ha resulted in similar dry weight of grassy and broad-leaf weeds with all other herbicidal treatments, and was superior to bispyribac-sodium 20 g/ha in controlling grassy weeds during 2012 and bispyribac-sodium 20-25 g/ha in controlling broad-leaf weeds during both the years. It provided almost complete control of sedges. The grain yield under penoxsulam 22.5 g/ha (5.68 t/ha in 2011 and 6.89 t/ha in 2012) was at par with its higher dose (25 g/ha) and more than its lower dose (20 g/ha). It also resulted in net returns (` 31921-55372/ha) and B:C ratio (2.03-2.68) almost similar/higher to recommended post-emergence herbicides. Weeds growing throughout the crop season reduced the grain yield of rice to the tune of 37.5 and 43.4% during 2011 and 2012, respectively. Penoxsulam 22.5 g/ha also performed well against weed complex in adaptive trials at farmers’ fields during Kharif 2017. There was no phyto-toxicity of penoxsulam even up to 50 g/ha on transplanted rice crop and also there was no residual phyto-toxicity on the succeeding wheat during 2011-12 to 2013-14. It also did not leave any detectable residual carry-over at harvest in soil, straw and rice grain when applied up to 45 g/ha.

Intensification

Land configurations

Rice-wheat

Weed management 

The field experiment was conducted during 2015-16 and 2016-17 at Norman E. Borlaug Crop Research Center, Pantnagar G.B Pant University of Agriculture & Technology, Pantnagar, U.S. Nagar (Uttarakhand) India, to study the crop intensification and establishment techniques influence on weed management under irrigated rice-wheat system. The experiment was laid out in a randomized block design with nine treatments and replicated thrice. The nine cropping sequence were evaluated for productivity. Density of these weeds was significantly affected by crop intensification and establishment techniques during both the years. In Kharif season, total weed density was recorded significantly lower in treatment rice (TPR) – wheat while the highest total weed density was recorded in rice (DSR) –vegetable pea – maize grain treatment during both the years. Weed density as affected by crop rotations maize (B) (cob + fodder) + cowpea (B) + sesbania (F)-2:1:2 - vegetable pea (B) + toria (F)-3:1 – groundnut (B) + mentha was found to be the the superior in terms of weed suppression.

Conservation tillage, Direct-seeded rice, Economics, Rice-wheat system,  Weed control

The present experiment was carried out in a split-plot design with four tillage practices in the main plot and three methods of weed control practices in sub plot with four replications at agronomical research farm of Birsa Agricultural University, Ranchi during 2009-10 to 2010-11 to find out the effective tillage methods adopted in direct-seeded rice and wheat with different weed control methods. Results revealed that in direct-seeded rice density of grassy, broad-leaved weeds and sedges accounted for 23.1, 59.2 and 17.7% and in wheat, grassy and broad-leaved weeds accounted for 5.7 and 94.3% respectively of total weed density. Conventional tilled plots had more number of weeds per unit area as compared to zero tilled. Conventional tilled both rice and wheat produced 25.3, 11.9 and 11.4% higher mean rice equivalent yield compare to mean yield due to other tillage combination. Two hand weeding (20 and 40 DAS for rice and 25 and 50 DAS for wheat) and application of recommended herbicides being at par gave higher rice equivalent yield than weedy check.

Carfentrazone

Halauxifen

Metsulfuron

Wheat

A study was undertaken during winter seasons of 2016-17 and 2017-18 at Uttar Banga Krishi Viswavidyalaya, Coochbehar, West Bengal to assess the comparative efficacy of various herbicides and to identify the effective herbicides for controlling broad-leaved weed flora in wheat. The experiment was laid out in a Randomized Block Design (RBD) with eleven herbicides combination viz. halauxifen-methyl ester+ florasulam 40.85% WG + polyglycol; metsulfuron methyl 20 WG + surfactant; carfentrazone 40 DF; 2,4-D Na 80 WP; 2,4-D E 38 EC; metsulfuron + carfentrazone +surfactant; 2,4-D-Na + carfentrazone; 2,4-D E + carfentrazone , halauxifen-methyl + florasulam+ carfentrazone + surfactant including a weedy check and weed free treatment. It was revealed that Polygonum alone constituted almost 72% of the total broad leaved weed population in both the years. Among the herbicidal treatments, metsulfuron + carfentrazone + surfactant recorded significantly lesser weed population (10.0 and 2.3/m2 during 30 and 60 days after spraying of post-emergence herbicides, respectively) vis-à-vis weed dry weight (11.2 and 4.5 g/m2 during 30 and 60 days after spraying of post-emergence herbicides, respectively) . This combination also recorded the highest broad leaf weed control efficiency (90.1 and 99.0% at 30 and 60 days after spraying, respectively) with the lowest weed index 6.0.The new molecule halauxifen-methyl ester + florasulam in combination with carfentrazone recorded 88.1 and 94.0% weed control efficiency. It was noted that Polygonum was killed by halauxifen-methyl ester + florasulam 40.85% WG + polyglycol, but it could not control Physalis minima, the second most important weed after Polygonum. Weed free treatment recorded significantly higher grain yield (5.39 t/ha) followed by metsulfuron + carfentrazone + surfactant treated plots (5.04 t/ha), the best performed treatments among various post-emergence herbicides combination used in the experiment. According to the linear regression, wheat crop was likely to produce very poor grain yield (less than 1.50 t/ha) when weed biomass exceeds 400 g/m2.

Grain yield, Maize

Pre-and post-emergence herbicides

Weed control efficiency

Weed index

A field experiment was conducted at Research Farm of Punjab Agricultural University, Ludhiana during Kharif 2016 and 2017 to find out the best chemical weed management practices in maize. Ten treatments were evaluated in a randomized block design with three replications. Treatments consisted of pre-emergence (PE) and post-emergence (PoE) herbicide applications along with weed-free check and weedy check. Experimental results indicated that pendimethalin 1.0 kg/ha as PE fb atrazine 0.75 kg/ha + 2,4-D amine 0.4 kg/ha at 25 DAS as PoE recorded lowest weed index (4.9 and 3.9% respectively, during Kharif 2016 and 2017) followed by treatment atrazine 1.5 kg/ha as pre-emergence fb tembotrione 120 g/ha as PoE at 25 DAS (5.6 and 4.4%, respectively). Grain yield was significantly higher (6.71 and 6.67 t/ha, respectively) with treatment weed-free than all other treatments however, it was statistically at par with treatment pendimethalin 1.0 kg/ha as PE fb atrazine 0.75 kg/ha + 2,4-D amine 0.4 kg/ha at 25 DAS as PoE (6.38 and 6.41 t/ha, respectively during Kharif 2016 and 2017) followed by atrazine 1.5 kg/ha as PE fb tembotrione 120 g/ha as PoE at 25 DAS (6.34 and 6.37 t/ha,  respectively).

Growth pattern

Economics

Linseed

Weed dynamics

Yield

A field experiment was conducted during Rabi season of 2016-17 and 2017-18 at Research cum Instructional Farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh to study weed dynamics, growth pattern, yield and economics of Linseed (Linum usitatissimum L.) under weed management practices. The experiment consisted ten treatments replicated thrice using the linseed variety ‘RLC-92’.The plant population, plant height and number of branches varied significantly among different weed management treatments. Linseed seed yield was significantly higher (1.94 t/ha) with hand weeding twice, which was statistically at par with isoproturon + metsulfuron-methyl (1 kg + 4 g/ha) post-emergence treatment (PoE), metsulfuron-methyl (4   g/ha) PoE and pendimethalin (1 kg/ha) pre-emergence treatment (PE) followed by (fb) metsulfuron-methyl (4 g/ha) PoE. Density and biomass of weed was the  lowest and weed control efficiency was higher with hand weeding twice 21 and 45 days after seeding (DAS) followed by isoproturon + metsulfuron-methyl (1 kg + 4 g/ha) PoE and metsulfuron-methyl (4 g/ha) PoE. The gross return was maximum with hand weeding twice 21 and 45 DAS while net return was maximum with isoproturon + metsulfuron-methyl (1 kg + 4 g/ha) PoE. The highest benefit: cost ratio (3.91) was recorded with metsulfuron-methyl (4 g/ha) PoE due to higher seed yield coupled with lower cost of chemical treatment.

Capsicum annuum L., Chilli, Cyperus scariosus, Cyprene, Cyprene epoxide, Cyprene alcohol, Plant growth regulator

Allelopathic effect of the essential oil of wild sedge- Cyperus scariosus, it’s polar and non-polar fractions, isolated compound-cyprene and its derivatives: cyprene epoxide and cyprene alcohol were screened for germination studies on chilli (Capsicum annuum L.). Chilli is a vegetable crop in Punjab which is having trouble shooting problem during its germination stage, which leads to the interruption in growth curve of the seedling. Treatment of seeds with oil, its fractions and its derivatives lead to stimulatory effect (approx. 75-100%) in terms of primary root and shoot length with collateral increase in dry and fresh weight of seedlings over control at 20 days. Oil and its polar fraction found to be the most effective in enhancing the root length and shoot length, and acts as potent plant growth regulator at the concentration of 0.5 µg/mL.

Fruit quality, Orchard, Mulching, Nectarine, Weed management

The study has assessed the efficacy of different orchard floor management treatments on weed management in ‘Snow Queen’ nectarine. The experiment was carried out in a randomized block design consisted of seven treatments having four replicates during the years 2016 and 2017. It has been found that the different orchard floor management treatments had a significant effect on weed density, weed fresh and dry weight, fruit quality and fruit yield of nectarine. All inorganic mulches (black polythene mulch, bicolour polythene mulch and nylon mulch mat) showed their superiority and provide complete elimination of weeds. Bicolour polythene mulch recorded maximum fruit size, weight, volume and TSS, whereas black polythene mulch recorded maximum fruit yield during both the years of study.

Cotton

Economics

Weed management

Yield

Field experiments were conducted during winter seasons of 2008-09 and 2009-10 at Eastern Block Farm, Tamil Nadu Agricultural University, Coimbatore to study the efficiency of new formulation of pre-emergence herbicide pendimethalin 38.7% on growth and development of cotton with better weed management in a cost effective manner, under irrigated condition. Pendimethalin 38.7% was tried in four different doses, viz. 1.5, 2.0, 2.5 and 4.0 kg/ha and it was compared with pendimethalin 30% 1.0 kg/ha, early post-emergence herbicide trifloxysulfuron, power weeders and hand weeding. The pre-emergence application of pendimethalin (38.7%) at 2.0 kg/ha at 3 days after seeding (DAS) followed by hand weeding and earthing at 45 DAS did not show any phytotoxic effect on cotton and recorded lower weed density and biomass with increased the seed cotton yield by about 41.5% over unweeded control and higher net returns.

Fodder crops 

Weed dynamics

Weed flora

Weed management

Appraisal has been made at the fodder farm of ICAR-IVRI, Izatnagar campus by following standard procedure adopted by AICRP on Weed Management (ICAR) during 2015 and 2016. Results revealed that Trianthema portulacastrum and Trianthema monogyna were widely distributed in the fodder farm during summer and rainy seasons. It produced flower continuously up to second fortnight of November with 224 to 504 seeds/plant and multiplied both by seeds (More than 80% germination of current seeds) and fragmented plant parts. Another broad-leaved weed Celosia argentea preferred the growing condition of fodder sorghum and it produced 1,716 to 3,496 seeds/plant. The broadleaved weed Coccinia grandis was associated with fodder maize and sorghum, and produced 2,934 to 4,428 seeds/plant. Numerous seed production capacity of these weeds supported its high profile emergence. Among the other weeds the grasses were widely distributed, whereas the sedges were appeared in patches. Three major broad-leaved weeds Coronopus didymus, Rumex dentatus and Cichorium intybus appeared during 1st, 2nd, 3rd and 4th cutting of berseem during winter season, respectively. The weeds Trianthema portulacastrum, Trianthema monogyna, Coccina grandis, Rumex dentatus and Cleome viscosa had shown the character of endozoochory dissemination. Uniform distribution of rainfall during 2015 caused rapid infestation of broad-leaved weeds (Trianthema sp., Coccinia grandis, Celosia argentea) whereas huge down pour within short period during monsoon season of 2016 caused submergence which, in turn, reduced infestation of broad-leaved weeds and side by side increased invasion of grasses. Mixed cropping of fodder maize (Variety ‘African Tall’) and fodder cowpea (Variety ‘Bundel Lobia 2’) controlled Trianthema sp. and maximum green fodder yield was obtained at 55 days after sowing beyond that cowpea showed competitive effect on maize. Turning the land from fodder sorghum to cowpea minimised distribution and seed production capacity of Celosia argentea. Mixed cropping of berseem (Variety ‘Wardan’) + gobhi sarson (Brassica napus var. napus) and berseem (Variety ‘Wardan’) + rye grass (Variety ‘Makkhan Grass’) reduced infestation of Coronopus didymus. Growing of dual purpose (grain-cum-green fodder) wheat variety ‘VL Gehun 829’ reduced infestation of resistant biotype of Phalaris minor.

Ageratum conyzoides, Indigenous knowledge, Soil fertility, Rice productivity, Weed utilization

Growers of the hill ecosystem, assess soil fertility by visualizing the luxuriant growth of weeds (Ageratum conyzoides). Since a long time, they have been using this as a soil fertility indicator as indigenous knowledge. Thus, the present study was conducted to quantify weed density, crop performance, soil fertility status and correlate with growers view by enquiring from respondents. A total of 78 respondents were interviewed and their responses were filled in unorganized questioners. The major parameters viz. weed density, rice grain yield and chemical properties of soil were considered in this study. It was found that growers of the area have strong indigenous perceptions for assessment of soil fertility. Higher density, better rice grain yield and chemical properties of soils were found better indicator of soil fertility as per grower’s perceptions.

Aquatic weeds

Water hyacinth

Utilization

Silage

Additives

Cassava powder

Water hyacinth (Eichhornia crassipes (Mart.) Solms) is one of the most productive plants on earth, but it is also considered as the world’s worst aquatic weed. An experiment was carried out with the objective of utilizing it by converting to silage for its usage as animal feed. The quality and palatability of water hyacinth silage prepared with additives such as molasses, cassava powder, and rice bran were assessed. The   completely randomized design (CRD) with 12 treatment combinations and 3 replications, was used. The treatments included: combination of wilted and fresh water hyacinth with or without rice straw or guinea grass and using any of the additives such as molasses, cassava flour and rice bran.  Wilted water hyacinth plus cassava powder (10%), wilted water hyacinth plus rice straw (10%) plus cassava powder (10%), and wilted water hyacinth plus guinea grass (10%) plus cassava powder (10%) had good fodder quality due to low pH. The odour of these combinations was rated as either ‘good’ or ‘very good’. The quality of rice bran added silages was low in terms of pH, odour and palatability; although its nutritional quality was high.  Rice bran enhanced crude protein, crude fat and ash content of silages. Molasses ensured the quality of silage by lowering pH and enhancing intake. Cassava powder addition in general reduced the pH of the silage and enhanced the palatability of silage.

Dry direct-seeded rice, Azimsulfuron, Pretilachlor, Weed management, Yield

A field experiment was conducted during the Kharif season of 2015 to 2017 for three years at Agricultural Research Station, Vadgaon Maval, Pune, Maharashtra to find out the efficacy of different weed control methods on dry direct-seeded rice and its economics. Pretilachlor 0.450 kg/ha as pre-emergence application (PE) at 2-3 days after sowing (DAS) followed by (fb) azimsulfuron 0.035 kg/ha as post-emergence application (PoE) at 25 DAS effectively managed weeds in dry-DSR and gave the higher grain yield (5.62 t/ha), net returns (` 82777/ha), higher B:C ratio (2.8) with lower weed index (2.78) and higher weed control efficiency (87.7%).

Chemical control

Herbicides

Manual weeding

Weeds

Field experiments was conducted to study the effect of weed control methods on wheat (Triticum aestivum L.) during Rabi seasons of 2014-15 and 15-16 at Agronomy Research Farm of NDUAT, Kumarganj, Ayodhya (U.P.). Pre-emergence application of pendimethalin + metribuzin (1.0 + 0.175 kg/ha) being at par with weed free and pendimethalin (1.0 kg/ha) followed by sulfosulfuron (0.025 kg/ha) significantly reduced the density of weeds as compared to other treatments. Pre-emergence application of pendimethalin +  metribuzin (1.0 + 0.175 kg/ha) significantly increased all growth and yield contributing characters, viz. plant height, dry matter accumulation, spikelength, grains/spike obtained with weed free. Among different herbicidal treatments, maximum grain and straw yields were recorded under pendimethalin + metribuzin (1.0 + 0.175 kg/ha) (4.22 and 5.70 t/ha, respectively). However, the highest benefit: cost ratio was recorded in weed free (1.97) followed by pendimethalin + metribuzin (1.0 + 0.175 kg/ha) (1.91).

Fluthiacet-methyl, Herbicides, Soybean, Weeds

A field experiment was conducted during rainy (Kharif) seasons of 2013 and 2014 at Agriculture Research Station, Mahatma Phule Agricultural University, Kasbe Digraj, Sangli, Maharashtra. Significant weed density reduction was recorded with fluthiacet-methyl at increased application rates of 5 g/ha to 15      g/ha. Fluthiacet-methyl 15 g/ha + 0.25% NIS controlled broad-leaved weeds effectively. Biomass and total broad-leaved weed density were the lowest with fluthiacet-methyl 15 g/ha + 0.25% NIS. Weed control efficiency was higher (80.86%) with fluthiacet-methyl 15 g/ha + 0.25% NIS. Seed yield was the highest (1.91 and 1.93 t/ha during 2013 and 2014, respectively) in weed free plot followed by fluthiacet-methyl 15 g/ha + 0.25% NIS applied as post-emergence (2-5 leaf stage of weeds) with the highest B:C ratio.

Economics, IWM, Soybean, Yield

A field experiment was conducted during 2010 to 2012 for three years at Agricultural Research Station, Karad Maharashtra to find out the suitable integrated weed management method in soybean. Post-emergence application of quizalofop-ethyl at 0.05 kg/ha + chlorimuron-ethyl at 0.009 kg/ha at 15 days after seeding (DAS) + hand weeding at 30 DAS, recorded lowest weed biomass (38.1 g/m2) with higher weed control efficiency (62%) and lower weed index (8.0). The some treatment also recorded the highest seed yield and net returns with lower weed index (8.0) in soybean.

Hand weeding

Net returns

Power weeder

Pre-emergence

Productivity

Field experiment on economics and productivity of sunflower with response to spacing and weed management practices was conducted at Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, during rainy season of (Kharif) 2016 and 2017 with objective of checking the suitability of spacing for moment of power weeder. Experiment was laid out in strip plot design and replicated thrice. The treatment comprised of five horizontal factors as plant spacing and five vertical factors as weed management practices. The higher cost of cultivation was registered with spacing 90 × 15 cm among different spacing and increased in gross returns, net returns, B:C ratio, per day return and seed yield with the spacing 75 × 25 cm. Hand weeding twice at 15 and 30 DAS recorded the higher cost of cultivation, gross returns, per day returns and seed yield among the different weed management practices during the both years of experimentation. Results of two year experimentation revealed that increased in net returns with pendimethalin at 1 kg/ha followed by hand weeding at 30 DAS and higher B:C ratio was recorded with pendimethalin at 1 kg/ha followed by weeder at 30 DAS.

Diuron

Polymulch

Weed control

Phytotoxicity

Field experiments were conducted at Professor Jayashankar Telangana State Agricultural University, Rajendranagar during Kharif 2017 for the evaluation of efficacy different doses of diuron in both red and black soils.  The treatment consisted of test herbicides such as, diuron 80% WP at 0.5 kg/ha, 0.75 kg/ha and 1.0 kg/ha along with registered formulation of pendimethalin 38.7% CS at 677 g/ha, intercropping with green manure crop, mechanical weeding thrice at 20, 40, 60 DAS and unweeded control. The experiment was laid out in a randomised block design replicated thrice. The weed flora of the experimental field in red soil was dominated by Cynodon dactylon, Rottboellia exaltata, Parthenium hysterophorus, Trianthema portulacastrum and Commelina benghalensis. While in case of black soil, predominant flora was Cynodon dactylon, Cyperus rotundus, Parthenium hysterophorus, Euphorbia geniculata, Tridax procumbens, Cyanotis cristata, Digera arvensis and Celosia argentia. The treatments, mechanical weeding thrice at 20, 40 and 60 DAS, polymulch treatments reduced the weed growth in both red and black soils. Among the herbicides, diuron at 1.0 kg/ha fb pyrithiobac-sodium + quizalofop-ethyl in red soil and both diuron at 1.0 kg/ha and 0.75 kg/ha along with sequential application of herbicides reduced the density of weeds. Diuron could reduce the broad-leaved weeds and grasses except itch grass. Sedges are also could not be reduced by diuron. The lower values of weed persistence index was obtained with herbicidal treatments i.e., diuron at 1.0 and 0.75 kg/ha fb pyrithiobac-sodium + quizalofop-ethyl. The crop resistance index and treatment efficiency index were superior in case of polymulch and mechanical weeding thrice at 20, 40 and 60 DAS.

Grubber, Khurpi, Performance, Power weeder, Wheel hoe 

The field performance of different weeding tools/implements viz. khurpi (hand hoe), grubber, wheel hoe, and power weeder were carried out at the Institute Research Farm, ICAR-Research Complex for Eastern Region, Patna, Bihar. Results revealed that actual field capacity of 0.0046±0.002, 0.0086±0.0002, 0.0189±0.0003, 0.0696±0.003 ha/h had associated with khurpi, grubber, wheel hoe and power weeder, respectively. Khurpi had recorded the maximum weeding efficiency (98.9%) and lowest in case grubber (74%). Similarly, power weeder contributed to higher plant damage (1.94%). Operational of khurpi had recorded maximum (Rs.6793/ha). A reasonable amount of savings of weeding operation were observed using grubber, wheel hoe, and power weeder as compared to khurpi.

Coffee plantations

Mikania micrantha

In Assam, the coffee plantations are confined in Chirang, Karbi Anglong and Dima Hasao districts and also has the potentiality for expansion in the foot hill regions of lower Brahmaputra Valley and Hill agro-climatic zones of the state. Weed management is the biggest problem for coffee cultivation in the state and Mikania micrantha is one of the most problematic weeds in most of the coffee plantations. To quantify the infestation of the weed in and around coffee growing areas, a survey was conducted in five coffee plantations and 19 locations of other plantation crops as well as open forests covering an area of 355 km2 in Karbi Anglong district of Assam. M. micrantha infestation was negligible to low in coffee plantations, which received two rounds of manual weeding whereas, the infestation was moderate to high where only one manual weeding or no weeding was done. In open forest, the density of the weed was quite high. Among the coffee estates surveyed, the highest infestation of M. micrantha was observed in the estates surrounded by open forests and neglected other plantation crops which served as a good seed source for this weed.

Cyperus rotundus

Dormancy

Nanoparticles

Phenols

Vanillic acid

Cyperus rotundus is one of the most invasive perennial sedge weed considered as the world’s worst weed. The tubers of the weed remain viable for more than three years and pass over the harsh weather period by preventing the germination of buds present in the tubers. Due to dormancy, the tubers may sustain in the soil for longer and interfere with the crops raised in the following season. Phenols are considered as the major factor of dormancy in Cyperus rotundus tubers. Among different phenolic acids, vanillic acid is dominated, found under long and continuous stress. Nanoparticles are capable to degrade the phenols. In order to confirm whether the nanoparticles have effect on degradation of phenol present in Cyperus rotundus, the dominant phenol present in the tuber i.e., vanillic acid was chosen. Experiment was conducted at the department of Nano Science and Technology, Tamil Nadu Agricultural University, Coimbatore to find the effect of different nanoparticles such as iron oxide, silver, titanium dioxide and zinc oxide on commercially available vanillic acid degradation during 2013-15. The maximum degradation of vanillic acid was observed with iron oxide nanoparticles at 25 mg i.e., 60.6% degradation compared to control. Titanium dioxide, zinc oxide and silver nanoparticles at 25 mg recorded the 54.5, 49.3 and 24.8% degradation, respectively.