REVIEW OF LITERATURE
Aromatic rice (Oryza sativa L.), has become one of the major exportable food commodities in recent years. One of the possible measures for sustaining rice production and grain quality of rice, particularly of scented rice is organic manure. Integrated use of organic materials along with chemical fertilizers may be an effective alternative approach for further improving levels of the crop yields without deteriorating soil health. Weeds are the major problem in scented rice of its early slow growth rate where herbicides have commonly used by farmer in rice culture but their continuous usage at higher quantity cause environmental pollution. There is thus a need to develop the effective and economical integrated nutrient and weed management for obtaining higher yields, profitability, and quality of crop.
The present study was initiated to assess the improvement in production potential and quality of aromatic rice with integrated nutrient and weed management. The literature pertaining to integrated nutrient and weed management practices on growth yield and quality of aromatic rice has been reviewed in this chapter.
2.1. Integrated Nutrient Management
2.1.1. Effect of Integrated Nutrient Management practices on growth, yield attributes and yield of rice
Harikesh et al. (2017) A field experiment was carried out at Agronomy Farm of Narendra Deva University of Agriculture and Technology, Narendra Nagar (Kumarganj), Faizabad (U.P.) during Kharif 2015 and 2016,they reported that among integrated nutrient management practices, growth attributes viz., plant height (cm), number of tillers (per m2), dry matter accumulation (g/m2) at 30, 60, 90 DAT and at harvest were recorded significantly higher with the application of 50% RDF(Recommended dose of fertilizer) + 50% N through vermicompost treatment during both the years and in pooled analysis.
Mahmud et al. (2016) were found that the effect of vermicompost and chemical fertilizers on the growth and yield components in rice, an experiment was carried out during December 2013 to June 2014, Results showed that the highest plant height, effective tillers per hill, panicle length, filled grains per panicle, 1000-grain weight, grain yield, straw yield and biological yield were obtained from the combination of 4 t ha-1 vermicompost with 100 kg /ha N, 16 kg/ ha P, 66 kg/ ha K, 12 kg/ ha S. It was observed that yield of rice can be increased substantially with the judicious application of organic fertilizer with chemical fertilizer.
Kumar et al. (2014) were found that combined application of organic and inorganic sources of nutrient in combination remarkably increased yield and yield attributes of rice than alone. 125% RDF + 5 t/ha vermicompost recorded significantly higher yield and yield attributes in comparison to other treatments and this was followed by 100% RDF + 5 t/ha vermicompost. 125% RDF + 5 t/ha vermicompost was increased the number of panicles (20.50%), panicle length (23.12%), panicle wt. (13.02%), 1000 grain wt. (12.90%), grain yield (31.15%), straw yield (37.12%) over control. The lower yield and yield attributes was recorded in control plot.
Mohanty et al. (2014), were found the effect of different nutrient management practices on rice reported that integrated nutrient management i.e.50% R.D.F. + 50% R.D.F. through organic sources (based on nitrogen requirement) gave the highest grain yield of 6.43 t /ha which was higher by 11.9 and 19.2% over recommended dose of fertilizer (RDF) and organic management (OM), respectively.
Dekhane et al, (2014) stated that performance of different organic and inorganic fertilizer on growth and yield of paddy crop during Kharif season. Application of 50 % N through RDF + 50% N through vermicompost recorded highest growth attributes like plant height was 42.2 cm and 118.1 cm, No. of tillers per plant was 8.7 and 12.1 at 45 DAT and at harvest time respectively, panicle length (22.3 cm), grains per panicle (128.0), 1000-grain weight (19.7 g) and grain yield (4.97 t/ha.) and straw yield (5.77 t/ha.) of rice than all other treatments.
Ranjitha et al. (2013) stated that the different nutrient management options, application of 50 % recommended dose of nitrogen (through urea) and remaining 50 % RDN through vermicompost resulted in significantly higher grain (5520.8 kg /ha) and straw yield (6264.9 kg /ha) followed by 100 % RDN (through urea) application.
Balasubramanian and Wahab (2012) found that growth and yield attributes of rice crop viz. productive tillers/ hill, dry matter production at harvest, filled grains/ panicle, 1000 grain weight, grain and straw yield were favourably influenced by combined application of inorganic fertilizers and organic manures.
Masciandaro et al. (2010) revealed that an increase of plant productivity (expressed as kg of seeds produced per plot) in the treatment with vermicompost and inorganic fertilizer i.e. Mixture of organic and inorganic (vermicompost +NPK) treatment plot.
Manivannan and Sriramachandrasekharan (2009) stated that Combined application of vermicompost (50% N) and urea (50% N) resulted in the highest 1000 grain weight which was at par with that of poultry manure (50% N) and urea (50% N) in AnnamalainagarPrabhakara et al. (2007) stated that application of 50 percent recommended dose of nitrogen through organic manure and remaining 50 percent RDN through inorganic fertilizers resulted in significantly taller plants (76.31 cm), maximum number of tillers hill-1 (46) maximum dry matter (165.27g /hill), grain yield and straw yield (8.35 and 8.58 t/ ha respectively) but was statistically at par with 100 percent RDN through inorganic sources of fertilizers.
Barik et al. (2006) revealed that application of vermicompost alone or in combination with 75% or 50% of recommended NPK fertilisers resulted in higher filled grains panicle-1 (82.3) than all other treatments including 100% RDN from sole application of urea on sandy loam soil of West Bengal during 2002 and 2003
Dinesh et al. (2006) found that highest grain yield with 50 percent compost + 50 percent NPK source, which was at par with 50 percent FYM + 50 percent NPK in the year 2004 and both the practices produced significantly higher grain yield over FYM or compost or NPK fertilizer alone. However, in the year 2005, 50 percent compost + 50 percent NPK proved better than all the nutrient sources.
Mishra et al. (2006) stated that the in different source of N i.e. FYM, vermicompost, poultry manure highest grain yield (64.3 q/ha) of aromatic rice (Pusa basmati-1) due to incorporation of 25% nitrogen through organic source and 75% nitrogen through urea.
Subhendu et al. (2005) found that the highest grain yield obtained in plots that received 50% nitrogen through inorganic fertilisers and 50% through FYM followed by the treatments received 75% nitrogen through inorganic fertilisers and 25% through FYM on clay loam soils of West Bengal
Das et al. (2002) A field experiment was conducted in Orissa, during 1999 to determine the effect of integrated application of vermicompost and chemical fertilizer on rice. The best results in terms of straw and grain yields were obtained with 50% vermicompost + 50% chemical fertilizers
Jeyabal and Kuppuswamy (2001) stated that integrated application of 50% N through vermicompost + 50%through recommended fertilizer N and biofertilizers recorded a grain yield of 6.25 t/ ha. It was 12.2% higher than that obtained with 100% fertilizer N alone during 1994-96 in Tamil Nadu
Sujathamma et al. (2001) found that significantly higher grain yield (3546 kg ha-1) and straw yield (5435 kg/ ha) were obtained with the application of 50% N through vermicompost + 50% N through chemical fertilizer compared to control (2978 and 4489 kg /ha, respectively).
Murali and Setty (2000) found that vermicompost @ 5 t/ha resulted in significantly higher plant height, number of tillers/hill, dry matter accumulation, higher number of panicles, number of grains/panicle,1000 seed weight, higher grain yield and straw yield over no vermicompost.
2.1.2. Effect of Integrated Nutrient Management practices on weed dynamic
2.1.2. Effect of Integrated Nutrient Management practices on nutrient uptake by crop
Harikesh et al. (2017) A field experiment was carried out at Agronomy Farm of Narendra Deva University of Agriculture and Technology, Narendra Nagar (Kumarganj), Faizabad (U.P.) during Kharif 2015 and 2016,they reported that among integrated nutrient management practices, quality attributes like hulling % and protein content in grain were recorded significantly higher with the application of 50% RDF + 50% N through vermicompost treatment during both the years and in pooled analysis.
Kumar et al. (2014) they found that 125% RDF + 5 t/ha vermicompost recorded significantly higher yield, yield attributes and in comparison to other treatments and this was followed by 100% RDF + 5 t/ha vermicompost. 125% RDF + 5 t/ha vermicompost was increased the N uptake in grain (36.81%) and straw (42.81%), P uptake in grain (32.62%) and straw (31.56%) and K uptake in grain (35.46%) and straw (25.39%) over control.
Arun et al. (2014) found that 125% RDF + 5 t/ha vermicompost recorded significantly nutrient uptake in comparison to other treatments and this was followed by 100% RDF + 5 t/ha vermicompost. 125% RDF +5 t/ha vermicompost was increased N uptake in grain (36.81%) and straw (42.81%), P uptake in grain (32.62%) and straw (31.56%) and K uptake in grain (35.46%) and straw (25.39%) over control. The lower nutrient uptake was recorded in control.
Ranjitha et al. (2013) studied the different nutrient management options and found the application of 50 % recommended dose of nitrogen (through urea) and remaining 50 % RDN through vermicompost resulted in significantly higher nutrient uptake (157.9, 30.7 and 166 N, P and K kg/ha, respectively) followed by 100 % RDN (through urea) application.
Mukesh kumar et al. (2012) reported that 100% recommended Nitrogen and Phosphorus fertilizer along with organic sources recorded higher N uptake in rice as compared to 100% recommended Nitrogen and Phosphorus fertilizer.
Acharya et al. (2012) found that nutrient uptake of rice was highest due to integrated nutrient application than that of inorganic nutrients alone, whereas lowest value was observed with control plot where no nutrient was applied.
Priyadarsini and Prasad (2003) studied that maximum N uptake by rice with the addition of 50% N through fertilizer + 50% N through organic source on sandy clay loam soil during kharif season at Bapatla.
Jeyabal and Kuppuswamy (2001) revealed that integrated application of 50% N through vermicompost. 50% via fertilizer N increased the N, P and K uptake by 15.3. 10.7 and 9.4%, respectively in rice over fertilizer N alone in rice – legume cropping system in Tamil Nadu.
Chaudhary et al. (2011) reported that 75% RDN + 25% N through vermicompost and 75% RDN + 25% N through FYM registered significantly higher NPK uptake than inorganic alone.
Jeyabal and Kuppuswamy (2001) found that integrated application of 50% N through vermicompost. 50% via fertilizer N increased the N, P and K uptake by 15.3. 10.7 and 9.4%. respectively in rice over fertilizer N alone in rice – legume cropping system in Tamil Nadu.
2.1.3. Effect of Integrated Nutrient Management practices on quality characters
Chaudhary et al. (2011) they found that there was no significant difference in Kernel length and L/B ratio with conjunctive application of RDF and organic manure or RDF alone.
Dawari and Sharma (2010) reported the mean data over the two years indicated that in basmati rice Kernal length and breadth before and after cooking was increased with conjunctive application of vermi compost, wheat residue and bio fertilizers, it was significant over vermi compost alone and farm yard manure alone.
Harish and Devasenapathy (2010) reported that the treatment with incorporation of green manure + vermicompost had higher L/B ratio before and after cooking which decreased its length and increased breadth after cooking in rice on clay soils of Coimbatore
Gautam et al. (2005) found that kernel length and breadth before and after cooking were not influenced by nitrogen application
Mrudula (2004) studied that better quality parameters like volume expansion ratio and amylose of rice by the application of 50% organics and 50% inorganics which was on a par with 100% RDN through organic source treatments on sandy clay loam soils of Bapatla.
Priyadarsini and Prasad (2003) studied that the grain quality characters like, head rice recovery, grain length and breadth and protein content were highest in integrated use of 50% nitrogen through inorganic source (urea) and 50% nitrogen through organic sources (FYM + Green manure) on clay loam soils of Bapatla.
Hemalatha et al. (2000) studied the application of vermicompost numerically increased the values of all quality parameters like hulling per cent, head rice recovery compared to no vermicompost application.
2.1.4 Effect of Integrated nutrient management practices on post-harvest physico-chemical properties of soil
Babar and Dongale (2013) studied that the different soil fertility parameters viz., bulk density, porosity, organic carbon and available nutrients (NPK) content in soil showed significant improvement with the application of organic, inorganic and organic + inorganic sources of nutrients compared to the control treatment. The available nutrients content in soil was also slightly higher under 50% NPK (inorganic fertiliser) + 50% N (manure) treatment compared to only chemical fertilizers.
Rao et al. (2013) found that pH of soil was not influenced statistically by various treatments. The continuous use of manures and fertilizer slightly lowered the pH. Increased dose of fertilizer decreased the pH.Roy (2013) studied that the maximum organic carbon, available NPK were recorded from the plots receiving 50% RDN through inorganic fertilizer and 50% through organic manures.
Surekha et al. (2013) revealed that integrated nutrient management (50% through inorganic and 50% through organic) brought about improvement in soil organic carbon available N, P and K as compared to inorganic fertiliser.
Srinivas et al. (2010) studied that after crop harvest available N,P and K content in soil was higher with application of RDF along with zinc compared to RDF alone and 50% RDF in combination with organic manures.
Yadav and Kumar (2009) found that combined use of organic manures and chemical fertilizers improved the physical condition of soil (decreased pH, ESP and EC from initial values, increase OC and available N, P and K) more effectively than continuous addition of chemical fertilizers alone.
Rather and Sharma (2009) studied that significant improvement in soil properties and fertility status was found under treatment of 100% Rec NPK + Vermicompost + Zinc + PSB. Organic carbon content of soil improved from 3.0 to 4.6 g kg-1 soil, Bulk density reduced from 1.50 to 1.32 Mg m-3, water holding capacity increased from 20.32 to 23.72 %, available N from 197.0 to 219.0 kg ha-1, available P from 13.0 to 19.1 kg ha-1, available K from 113.0 to 130.4 kg ha-1 and available Zn from 1.50 to 1.87 mg kg-1 soil by the integration of organics with inorganics.
Saha et al. (2007) found that highest total N in soil was observed with the application of 75% RDF along with pelleted form of organic manure (through 0.4 t ha-1 Biomax it contains 5% N, 0.88% P,0.83% K, 41.23% Cr and 4.8% Pb). The P and K status of soil was also higher with the treatment.
Fan et al. (2005) revealed that combination of organic and inorganic fertilization enhanced the accumulation of soil organic carbon and maintained the highest productivity.
Rajkhowa et al. (2003) found that soil organic carbon, available N, P and K status in soil improved significantly with vermicompost alone or in combination with fertilizer.
Sudhakar et al. (2002) revealed that application of chemical fertilizers along with vermicompost resulted in greater availability of micronutrients.
Bandyopadhyay and Puste (2002) studied that the application of 3 t ha-1 FYM or 3.65 t ha-1 rice straw with 25% recommended dose (100:60:60 kg ha-1 NPK) to rice in rice-rice cropping system in the red and laterite soils of West Bengal improved the available NPK content of the soil over sole fertilizer treatments.
Singh et al. (2001) reported that the organic manuring on 50% N equivalent basis (120 kg RDN) to rice through FYM, sesbania or carpet waste improved the nutrient status and sustained their initial values.
2.1.5. Effect of Integrated Nutrient Management practices on economics
Mohanty et al. (2014), found that the rice crop with integrated nutrient management i. e. 50% R.D.F. + 50% R.D.F. through organic sources (based on nitrogen requirement) practices realized the highest gross return (Rs. 75586 /ha) but the net return was at par with RDF ( Rs. 40251 /ha). The B:C ratio (Rs. 2.45 /ha) was the highest with R.D.F. followed by INM (Rs.2.16 /ha).
Lhungdim et al.(2014) found that the application of 100% RDF through inorganic fertilizers recorded higher net returns and benefit cost ratio as compared to other treatments i.e., 25% RDF + FYM 15 t /ha and 50% RDF + FYM 10 t /ha.
Kumari et al. (2010) studied that B:C ratio was higher in scented rice with application of RDF alone compared to sole organic alone treatment, due to increasing cost.
Chaudhary et al. (2011) found that among different nitrogen management practices, higher mean benefit cost ratio was recorded under100% RDN followed by 75% RDN + 25% FYM
Borkar et al. (2008) revealed the application of 100 percent nitrogen through fertilizer recorded maximum net return (Rs 15331.80 /ha) and B: C ratio (2.08) when compared to that of 50 percent N through fertilizer + 50 percent N through FYM with a net return of (Rs 9645 /ha) and B: C ratio (1.51).
Barik et al. (2008) found that the highest net returns (?15245 /ha) and return per rupee investment (2.11) were achieved from application of 60% RD of N from urea and 40% RDN from vermicompost, it was equivalent with the supply of 100% RDN entirely from urea (2.09) on sandy loam soils of West Bengal
Jat et al. (2015) from Varnasi found that 100% N through fertilizers recorded higher net returns followed by 50% RDN through fertilizers + 50% through FYM and was lowest with 100% RDN through FYM.
Lhungdim et al. (2014) found that the application of 100% RDF through inorganic fertilizers recorded higher net returns and benefit cost ratio as compared to other treatments i.e., 25% RDF + FYM 15 t /ha and 50% RDF + FYM 10 t /ha.
Borkar et al. (2008) found that the application of 100 percent nitrogen through fertilizer recorded maximum net return (Rs 15331.80 /ha) and B: C ratio (2.08) when compared to that of 50 percent N through fertilizer + 50 percent N through FYM with a NMR of (Rs 9645 /ha) and B: C ratio (1.51)
2.2. Integrated Weed Management Practices
No single weed control method could solve the weed problem in transplanted rice. A combination of weed control method is thus needed to achieve maximum benefits.
2.2.1. Effect of Integrated Weed Management practices on growth and yield attributes and yield
Gnanavel and Anbhazhagan (2010) found that the application of Oxyflourfen (0.25 kg a.i./ ha) + Bispyribac sodium (0.05 kg a.i./ ha) + metsulfuron methyl (0.01 kg a.i./ ha) has recorded higher plant height (113 cm) and number of productive tillers (318.62 m2)
Yadav et al. (2009) found that the application of Bispyribac 25 g ha-1 at 15 or 25 DAT was adjudged the most suitable herbicidal treatment resulting in 174-199 % increase in the rice grain yield over weedy check
Raju et al. (2003) studied the effect of pre emergence application of Pretilachlor plus Safener 0.3 kg /ha, Butachlor 1 kg/ ha and post emergence herbicide like Butanil 3.0 kg/ ha on 4, 8 and 15 days after sowing. They found that Pretilachlor plus Safener 0.3 kg /ha gave the highest yield attributes (productive tillers /m2, number of grains/ panicle and 1000 grain weight) and grain yield.
Mandhata and Singh (2010) found that application of pretilachlor (0.75 kg /ha) followed by 2, 4-D (0.5 kg/ ha) recorded significantly higher plant height (96.08 cm), tillers (374.31 /m2), dry matter accumulation (889 g/ m2) and yield parameters like higher panicles (319.86 /m2), panicle length (25.83 cm), grains per panicle (162.67) and thousand grain weight (26.43 g).
Sanjoy Saha, (2009) observed that Pre-emergence application of bensulfuron methyl + pretilachlor @ 50 + 500 g/ ha recorded effective panicles (267 /m2) and higher grain yield of 5.86 t /ha
Yadav et al. (2009) found that bispyribac sodium applied at 25 g/ ha at 25 DAT has recorded higher plant height (90.8 cm), effective tillers (58.7 /m2) and panicle length (21.5) than Bispyribac sodium applied at 25 g /ha at 15 DAT (88.9 cm, 57.8 /m2 and 21.1 cm, respectively
Walia et al. (2008a) observed that Pre-emergence application of pendimethalin at 750 g /ha followed by post emergence application of Bispyribac sodium at 20 g/ ha at 30 DAS has recorded higher plant height (80.1 cm), tillers (310 /m2) and panicle weight (21.7 g)
Walia et al. (2008b) found that Pre-emergence application of pendimethalin at 750 g/ ha followed by post emergence application of Bispyribac sodium at 25 g /ha at 30 DAS registered significantly higher plant height (59.2 cm), effective tillers (50.4 /m2) and panicle length (21.4 cm).
Singh et al. (2005) found maximum weed dry matter reduction was achieved under herbicide (Butachlor at 1.5 kg ha-1) plus two hand weedings in transplanted rice. The highest yield (4623 kg ha-1) was obtained with the application of herbicide supplemented with hand weedings in transplanted rice
Evelyn Javier and Fernando Garica et al. (2005) found that the application of pretilachlor at 1.5 l /ha at 3 DAS followed by Bispyribac sodium at 400 g /ha recorded higher number of tillers (506 /m2), plant height (61.4 cm), plant dry weight (660.3 g/ m2), panicle (362 /m2), filled grains (16512 /m2) and percent fertility (75 %).
2.2.2. Effect of Integrated Weed Management practices on weed dynamics of rice
Ravisankar et al., (2008) revealed that pre-emergence application of pretilachlor 0.3 kg/ha on 2 days after sowing followed by hand weeding at 45 days after sowing registered lower total weed density (53.6/m2) and higher weed control efficiency, as well as markedly improved the growth and yield parameters and grain yield (5.6 t/ha) of wet seeded rice
Gnanavel and Anbhazhagan, (2010) found that pre-emergence application of Oxyfluorfen @ 0.25 kg ha-1 followed by postemergence application of bispyribac sodium 0.05 kg /ha recorded the least weed count and weed dry matter production (11 m-2 and 114.65 kg /ha, respectively) and highest WCE (90.12 %) favoring higher grain yield of aromatic rice (5.32 t /ha)
Walia et al. (2008a) An experiment conducted at University Seed Farm, Kaparthula revealed that the post emergence application of bispyribac at 25 and 30 g /ha in dry seeded rice resulted in lesser weed dry weight (2.7 and 2.2 q /ha, respectively) and produced significantly higher grain yield than unweeded control
Walia et al. (2008b) found that significantly lesser dry weight of weeds (2.95 q /ha) and higher rice grain yield (56.18 q /ha) with the pre-emergence application of pendimethalin @ 0.75 kg /ha followed by post-emergence application of bispyribac 25 g/ ha.
Evelyn Javier and Fernando Garica (2005) observed that the use of Pretilachlor at 1.5 l/ ha sprayed at 3 DAS followed by Bisbyribac-sodium at 400 g/ ha at 13 DAS resulted in lower weed density (13 /m2), weed dry weight (8.7 g/m2) and an increased yield of 67-70 % over uncontrolled weed plot.
Samar et al. (2007) An experiment to evaluate the effects of herbicides for managing weeds and optimizing the yield of wet seeded rice. It was concluded that application of Pendimethalin(1000 g a.i. /ha) or Pretilachlor with Safener (500 g a.i./ha) as pre-emergence applications followed by one hand-weeding were effective in controlling weeds, increasing grain yield of rice, and resulting in higher net returns than the weed-free treatment.
Mahajan et al. (2003) studied that application of Pretilachlor alone or in combination with Safener and hand weeding resulted in the lowest total weed density and dry matter and grain yield and number of panicles.
Kalhirvelan and Vaiyapuri (2003) found the effect of weed management pratices on transplanted rice. The application of Pretilachlor at 187, 250 or 375 g/ ha, Pretilachlor and 2, 4 D at 180 + 180, 240+ 240 and 300+ 300 g/ ha with twice hand weeding. They found that hand weeding recorded the lowest weed population (2.78 /m2) and weed dry weight (155.7 kg /ha). Pretilachlor and 2, 4-D at 300 + 300 g /ha caused the lowest weed density and weed dry weight. Hand weeding recorded the highest grain and straw yields (5.81 and 7. 26 t /ha, respectively) than Pretilachlor and 2, 4-D (5. 55 and 6.89 t/ ha).
Moorthy et al. (2002) observed that the efficacy of pre and post emergence herbicides in controlling weeds in rainfed upland direct sown rice. The application of Pretilachlor 625 g /ha, and Butachlor 1600 g /haon 2 days after sowing and the treatments gave effective weed control and produced highest grain yield compared with twice hand weeding on 20 and 40 DAT.
Tamilselvan and Budhar (2001) found that the effects of pre emergence herbicides Pretilachlor 0.4 kg /ha, Pretilachlor 0.4 kg a.i. /ha on rice. The herbicides were applied 8 days after sowing. The density and dry weight of weeds at 40 DAS were lower in herbicide treated plots than in unweeded and hand weeded plots. The highest number of productive tillers/ hill was obtained with Pretilachlor 0,40 kg a.i. /ha (14.2). The number of filled grain /panicle was the highest with Pretilachlor 0.40 kg a.i. /ha (126.3). The weed control treatment had effect in increasing grain yield.
2.2.3 Effect of Integrated Weed Management practices on quality of rice
2.2.4 Effect of integrated weed management practices on nutrient uptake by crop and weeds
Patro et al. (2011) found that nutrient concentration in weeds and grain as well as in straw was not affected significantly by weed management practices. Nutrient removal by weeds was least in weed free check followed by butachlor + one hand weeding. The N, P and K uptake both in grain and straw were higher in weed free plots followed by butachlor + one hand weeding
Dharumarajan et al. (2009) revealed that N, P and K removal by weeds was highest in control plot and pretiachlor at 1.5 kg/ ha followed by hand weeding recorded lowest at active tillering and panicle initiation stages.
Sharma et al. (2007) found that weeds under two hand weeding treatments removed 6.2 kg /ha N, 1.7 kg P and 8.4 kg K /ha which were corresponding to 9.2, 9.0 and 8.9 per cent of total N, P and K removal from the soil.
Rana et al. (2000) found that pretilachlor 0.80 kg/ ha remained statistically at par with hand weeding twice resulted significantly lower uptake of NPK by weeds and higher by rice crop followed by butachlor at 1.5 kg /ha.
Sathyamoorthy, (2004) found that pre emergence application of butachlor followed by one and two hand weeding recorded lesser nutrient removal by weeds, however at 35 and 55 DAS hand weeding registered lowest nutrient removal by weeds
Nath and Pandey, (2013) found that lowest nutrient uptake by weeds and highest by crop was recorded in weed free treatments which was statistically at par with penoxsulam 25 g/ ha and two hand weeding
Sunil et al. (2011) revealed that pre-emergence application of bensulfuron methyl + pretilachlor (6.6 GR) @ 0.06 + 0.60 kg a.i. /ha + one intercultivation at 40 days after sowing recorded significantly higher N, P2O5 AND K2O uptake (107.70, 19.28 and 77.71 kg N, P and K /ha , respectively).
Mandhata Singh and Singh (2010) studied that in direct-seeded rice application of Pretilachlor fb 2, 4-D (0.75 fb 0.5 kg/ ha) recorded significantly higher uptake of nutrients by crop (88.68, 21.40 and 117.5 kg N, P and K/ ha, respectively).
Singh et al. (2005) studied that in direct seeded rice, uptake of nutrient by rice was higher in weed free condition (55.9, 26 and 69.5 kg/ ha of N, P and K respectively). Among other weed control treatments, hand weeding at 20 and 40 DAS recorded higher nutrient uptake by the crop (47.5, 18.1 and 58 kg/ ha of N, P and K respectively).
Bhanu Rekha et al. (2003) observed that in transplanted rice, uptake of nutrient by rice was higher in weed free condition (88.4, 22.9 and 83.5 kg N, P and K /ha, respectively). Hand weedings twice at 20 and 40 DAT recorded the higher nutrient uptake by grain (55.9, 13.1, 15.8 kg N, P and K /ha, respectively) and straw (25.2, 6.7, 52.3 kg N, P and K /ha, respectively).
Rana et al. (2000) found that the uptake of N, P and K in this treatment was 108.1, 24.3 and 126.5 kg ha-1, respectively which was 73.88, 95.97 and 60.53 per cent more than weedy check
2.2.5 Effect of integrated weed management practices on post- harvest physico-chemical properties of soil
Bera and Ghosh (2013) observed that the effects of bispyribac- sodium 10% SC and butachlor 50% SC on soil physio-chemical properties and microflora in transplanted rice over two seasons. The results revealed that the soil pH, electric conductivity, organic carbon content, total nitrogen, available phosphorus and potash did not vary significantly with tested herbicides at 60 days after application.
2.2.6 Effect of integrated weed management practices on Economics
Sunil et al. (2011) studied that application of bensulfuron methyl + pretilachlor (6.6 GR) at 0.06 + 0.60 kg a.i. /ha along with one Intercultivation at 40 days after sowing recorded maximum net returns (Rs. 25193/ ha) and higher benefit cost ratio of 2.29.
Abdul Khaliq et al. (2011b) found that the application of Bispyribac sodium 30 g a.i/ ha resulted in maximum net benefits of 107078 PKR (Pakistani Rupees) per ha and marginal and dominance analysis revealed that Bispyribac sodium was the best treatment with MRR of 23076 %
Ravishankar et al. (2008) observed that pretilachlor at 2 DAS gave better net returns (Rs. 16716 /ha) and B:C ratio (2.16) than at 5 DAS and hand weeding in wet seeded rice.
Raju et al. (2002) studied that in terms of economics, pre-emergence application of pretilachlor + safener followed by hand weedings twice at 30 and 45 DAS recorded higher B: C value of 4.03 compared to pretilachlor + safener followed by hand weedings once at 30DAS.
From the array of literature, it is evident that integrated nutrient management and weed management favourably influenced the growth, yield, quality and economics of transplanted rice without deteriorating the soil fertility. Application of organic manures integrated with inorganic fertilizers is essential in the present day agriculture, this will help to maintain soil fertility, sustain crop productivity and protect environment. In this regard, no systematic work has been taken up to study the combined influence of nutrient and weed management practices on rice. Hence, the present investigation was proposed to evolve an integrated efficient and ecofriendly nutrient and weed management packages for augmenting the productivity of transplanted rice.