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Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 6 (2017) pp. 2844-2857 Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2017.606.338 Pre and Post Emergence Application of Imazthapyr on N Uptake, Nodulation and Microbial Population of Chickpea Sown after Rice in Vertisols of C. G. Anjum Ahmad*, Tapas Chowdhury, Sudhir Kumar Taunk, Devendra Dewangan, and A.P. Singh Department of Agronomy, Microbiology, Indira Gandhi Krishi Vishwa Vidyalaya, Raipur - 492 012, India *Corresponding author ABSTRACT Keywords Imazethapyr, Nodulation, Chickpea, N Uptake, Microbial activities. Article Info Accepted: 26 May 2017 Available Online: 10 June 2017 A field experiment was conducted at the Agronomy Research Farm of IGKV, Raipur, during the Rabi season of 2010-11 and 2011-12. Incorporation of tillage and weed management practices considerably improved the yield of chickpea interms of N-uptake, number of nodules per plant and microbial activities of rice rhizosphere. Results indicated that, among the tillage management practices, higher N uptake, number of nodules and microbial activities were obtained with CT which was followed by MT and ZT. Among the various weed management practices, N-uptake and number of nodules were maximum under one HW at 20 DAS, followed by the treatments of POE application of imazethapyr @ 90 g ha-1 and POE imazethapyr @ 80 g ha-1, respectively. Whereas, microbial population, basal soil respiration and dehydrogenase enzyme activity of experimental field was significantly higher under weedy check plot, followed by one HW at 20 DAS and POE application of imazethapyr @ 90 g ha-1 during both the years. Introduction Chickpea (Cicer arietinum L.) is an ancient crop and is grown in tropical, subtropical, and temperate regions of the country and in recent years. Chhattisgarh region is dominated by rice crop in rainy (kharif) season followed by cultivation of wheat, oilseed and pulses in winter (rabi) season. In Chhattisgarh, chickpea is cultivated in an area of about 3.20 Lakh ha with an average production of 2.12 Lakh tonnes and productivity of 663 kg ha-1. The average productivity of chickpea is still below one ton per hectare, which is considered low by any standards. As yield is a very complex character depending on number of component characters, the knowledge of the association between the yield and its components and among the components themselves is of immense practical value in making selections. In spite of the importance of this crop in our daily diet and in agricultural production system, the productivity of this crop is very low in India as well as in Chhattisgarh. Weed competition is considered as one of the most important causes of low productivity and inferior quality of chickpea in Chhattisgarh. Considerable yield losses in 2844 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 chickpea recorded to the extent of 88 per cent if weeds are not controlled within critical growth period (Bhalla et al., 1998). Appropriately selected herbicides may perform an important role in weed infestation reduction, increasing weeds resistance to herbicides, high cost and especially, negative effects of herbicides on environment have increased the need of non-chemical weed control in agro ecosystems (Augustin, 2003). Crop rotation, the tillage systems, application of agrochemicals and other agricultural practices affect the soil seed bank and weed flora (Marshall et al., 2003). In an integrated approach, the development of cropping systems such as appropriate spatial arrangement and efficient tillage will help crops themselves to compete with weeds. Manipulation of cropping systems for the purpose of improving integrated weed management requires a good understanding of weed dynamics and influences of crop and soil-related factors on weed life cycles (Davis and Liebman, 2003). Weed flora have changed over the past century, with either increasing or decreasing species abundance depending on the management (Bagment, 2000). Chickpea grown in succession with rice and soybean under irrigated condition infested heavily with weeds affected the growth and yield of chickpea. Crop losses of 90% are possible in weedy situations (Knights, 1991) and lack of registered post-emergence herbicides for broadleaf weeds reduces the options for weed management. Hand and mechanical weed control methods traditionally followed in the spring crop are not effective in winter sown chickpea besides being costly and uneconomical. Because of the sensitivity of chickpea to herbicides, most effective herbicides are pre-sowing and preemergence soil-acting chemicals and their efficacy is highly dependent on soil type, moisture, temperature and weed flora. Postemergence herbicides, particularly those for broad-leaf weeds are few. There is a need to identify more effective herbicides with broader spectrum of weed control and wide adaptability. An integrated approach involving herbicides and cultural practices to improve crop competitiveness is needed to develop effective and economic control measure. Materials and Methods A field experiment was conducted during rabi seasons of 2010-11 and 2011-12 at the Research cum Instructional Farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur (Chhattisgarh). The soil of experimental field was clayey in texture, low in nitrogen, medium in phosphorus and high in potassium contents with neutral pH. The experiment was laid out in Split Plot Design with three replications(Gomez and Gomez 1984). The treatments were divided into main and sub plots (tillage and weed management practices). Three tillage practices viz. conventional tillage (T1), minimum tillage (T2) and zero tillage (T3) in main plot Most mechanical weed control methods, such as hoeing, tillage, harrowing, torsion weeding, finger weeding and brush weeding, are used at very early weed growth stages (Singh, 2014; Kewat, 2014). and nine weed management practices as pendimethalin @ 1000 g ha-1 PE (W1), imazethapyr @ 80 g ha-1 PE (W2), imazethapyr @ 90 g ha-1 PE (W3), imazethapyr @ 100 g ha-1 PE (W4) at 2 DAS, imazethapyr @ 70 g ha-1 POE (W5), imazethapyr @ 80 g ha-1 POE (W6), imazethapyr @ 90 g ha-1 POE (W7) at 20 DAS, one hand weeding at 20 DAS (W8) and weedy check (W9), in sub plots. Removing weeds or patch of weeds by hand is often the most effective way to prevent that weed from spreading and therefore from becoming a 2845 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 serious problem (Zimdhal, 2007).The N, P, K through diamonium phosphate and muriate of potash were applied as basal at sowing of the crop. Fertilizers alter the nutrient level in the agro-ecosystems and therefore they may directly affect weed population dynamics and crop weed competitions (Robert et al., 2004; Babu and Jain, 2012). Strong effects can be observed by manipulating fertilizer timing, dosage, and placement in order to reduce weed interference in crops (Dubey, 2014). Placement of fertilizer significantly reduced the density and dry biomass of weed and produced higher grain yield than broadcast method of fertilizer application (Pandey et al., 2006; Lodha et al., 2010). One protective irrigation gave at the time of sowing. Optimum time and number of irrigation reduces the density and weight of weeds (Das and Yaduraju, 2007; Verma, 2014). The chickpea variety JG-226 was sown as test crop in 2nd fortnight of November 2010 and 2011 and harvesting was done in 1st fortnight of March 2011 and 2012, respectively. Nitrogen uptake by crop and weeds The sample of crop and weeds grain and stover were dried in oven at 60ºC till constant weight after sun drying. N content (%) was determined by Micro Kjeldahl method (Jackson, 1967). The nitrogen uptake was calculated for each treatment separately using the following formula. Nitrogen uptake by grain = N Concentration (%) in grain x Grain yield (kg ha-1) / 100 Nitrogen uptake by stover = N Concentration (%) in stover x Stover yield (kg ha-1) / 100 The uptake of N was expressed in kg ha-1 Number of nodules plant-1 The number of nodules per plant were recorded at 20, 40 and 60 DAS. The roots removed from the 3 plants for root studies, were used to count the number of nodules. The nodules of each root were counted and mean value was noted as number of nodules plant-1. Microbial analysis Population count study Bacterial and fungal population was counted by using serial dilution technique (Subba Rao, 1988). One gm of soil sample was suspended in 9 ml of sterile water in a dilution tube (Tuladhar, 1983) and shaken for 15 min. This constituted 10-1 concentration. Using a fresh sterile pipette took 1 ml of this suspension and 9 ml sterile water was then added to get 10-2 dilution. The sequence was continued till a dilution of 10-7 was reached. Different media was prepared for isolation of micro-organism. Thornton’s Asparagine Mannitol agar media (Thornton, 1922) for bacteria and Rose Bengal agar media (Martin, 1950) for fungi were used, which were sterilized at 121ºC for 15 min. 1 ml of desired solution of freshly mixed suspension was transferred into the sterile petridish using sterile tip of micro-pipette. 10-3 to 10-5 dilutions for fungi and 10-5 to 10-7 dilutions for bacteria were used. Subsequently, about 15ml of partially cooled appropriate medium was poured into each plate and carefully swirl to thoroughly mix the contents (Plate 3b). After the media got solidified invert the plates and kept in an incubator at respective incubation temperature for different microorganisms (28°C for fungi and 37°C for bacteria). After specified period of growth (48 hrs for bacteria and 96 hrs for fungi), colonies were counted and population was enumerated 2846 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 by using formula given by Schmidt and Caldwell, 1967. Number of bacteria / fungi in 1gm soil= No. of CFU x Dilution N= Normality of acid. E= Equivalent weight, i.e. 22. Dehydrogenase activity Dry weight of 1 gm moist soil x aliquot taken Basal Soil Respiration study This study was conducted to know the respiration rate of microflora present in the crop rhizosphere soil. Basal soil respiration was calculated by measuring the CO2 evolution rates (Anderson, 1982). 100 g soil (oven dry basis) was taken in 1L conical flask. Then water is added to bring its moisture content to field capacity. 20 ml of 0.5N NaOH was taken in test tubes. The tubes were then hanged with the help of thread inside the conical flasks without touching the soil and kept the flasks air tight by rubber stoppers and note down the time. The flasks were kept in an incubator at 28°C for about 20 hrs. After incubation test tubes were taken out from the flask and noted down the time to calculate the period of incubation from the time as noted down above. Immediately transferred the 0.5N NaOH solution from the test tube to a 150ml conical flask. Several washings of the tubes were done for complete transfer 5 ml of 3N BaCl2 solution and few drops of phenolphthalein indicator were added. Titrated the content with standard 0.5N H2SO4 slowly until the pink colour just disappears. After getting the end point recorded the exact amount of acid required for titration. Soil respiration (mg of CO2/h/100g soil) = (B-V) NE/ hours of incubation Where, B = Volume of acid (ml) needed for the blank. V= Volume of acid (ml) needed for the NaOH exposed to soil. The procedure to evaluate the dehydrogenase activity of soil described by Klein et al., (1971). 1 gm air dried soil sample was taken in a 15 ml airtight screw capped test tube. 0.2 ml of 3% TTC solution was added in each of the tubes to saturate the soil. 0.5 ml of distilled water was also added in each tube. Gently tap the bottom of the tube to drive out all trapped oxygen so that a water seal was formed above the soil. No air bubbles were formed that was ensured. The tubes were incubated at 37 0C for 24 hrs. Then 10 ml of methanol was added. Shake it vigorously and allowed to stand for 6 hrs. Clear pink coloured supernatant was withdrawn and readings were taken with a spectrophotometer. The amount of TPF formed was calculated from the standard curve drawn in the range of 10 mg to 90 mg TPF/ml. Results and Discussion Nitrogen uptake by crop and weeds Data on quality parameters viz. nitrogen uptake table 2 indicated substantial variations due to tillage and weed management practices. The differences with respect to the nitrogen uptake were significant. Conventional tillage was found to contain maximum N uptake (by crop 29.66 kg ha-1 nitrogen and by weed 33.72 kg ha-1 nitrogen) and significantly higher than minimum and zero tillage during both the years. Hand weeding further excel all other treatments with respect to N uptake as it took maximum N uptake by crop (33.56 kg ha-1 nitrogen) and weeds (17.25 kg ha-1 nitrogen), which was significantly superior over pre-emergence and post-emergence herbicides (pendimethalin 2847 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 and imazethapyr) and weedy check plot. The weed-free treatment had more nitrogen uptake in grain and stalk than the weedy check during both the years. This was simply because of low shoot dry-matter production and low availability of these nutrients, as major amounts of nutrient were depleted by weeds. In weedy treatments, 37.5 kg N, 11.6 kg P and 38.3 kg K/ha were depleted in comparison to full-season weed-free conditions. The results are in conformity with the findings of Vengris et al., (1953), who reported vigorous growth and higher biomass of weeds resulted in more nutrient depletion. Number of nodules plant-1 The tillage and weed management practices significantly influenced the number of nodules per plant at all the growth stages of chickpea crop except 20 DAS during both the years. Tillage practices enhanced the number of nodules per plant significantly in chickpea during all the stages of crop growth. Conventional tillage proved to be favourable for producing significantly greater number of root nodules and it was followed by minimum and zero tillage, in descending order, in both the years. The treatment of one hand weeding at 20 DAS (W8) superseded all the herbicidal treatments with respect to maximum nodulation, as it contains 10.56, 26.33 and 38.75 root nodules per plant at 20, 40, 60 DAS, respectively. Among the herbicidal treatments, imazethapyr @ 90 g ha-1 POE (W7) produced significantly greater number of nodules per plant as compared to other treatments at all the growth stages during both the years. The treatments of imazethapyr @ 80 and 70 g ha-1 as post-emergent were next, in order, and produced statistically greater number of nodules as compared to weedy check. Other herbicidal treatments also proved better than weedy check at all the growth stages under study during both the years (Table 3). Hand-weeding twice recorded the maximum number of nodules/plant. Ahlawat et al., (1985). All the weed-control treatments proved superior to the unweeded check treatment. Hand weeding at 25 and 45 days was found most promising. Malik et al., (1988) also reported similar results. Results indicated that inter-culture + hand weeding done at 20 and 40 DAS recorded significantly higher nodulation as compared to rest of the treatments except pendimethalin @ 0.75 kg/ha. Similar results were also reported by Singh and Singh (1998), wherein, they found the highest nodulation in hand weeded plot and the lowest in fluchloralin treated plot. These results are in agreement with the results of Rajput et al., (1998) who observed higher nodule weight under hand weeded and pendimethalin application over unweeded control in chickpea. Micro-flora studies Bacterial population study The result on total bacterial population on rhizosphere soil as affected by different tillage and weed management practices were recorded at definite interval and tabulated in table 1. In rice-chickpea cropping sequence, the bacterial population study as affected by different tillage management practices, which indicated that tillage system did not impart any effect on batcterial population after harvest of the crop. Similar findings were also reported by Singh et al., (2007) who clearly mentioned that relatively higher availability of soil organic matter at lower soil profile under conventional tillage may be due to even distribution of crop residues and other nutrients throughout the plough zone. This may possibly account for observed higher counts of soil microflora at lower (7.5-15cm.) soil zone under conventional tillage than the 2848 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 minimum tillage. Brady (1985) reported that tillage facilitates the aeration of soil hence the microbial population increases. Singh et al., (2007) also found higher microbial populations under conventional tillage system at lower soil depth (7.5-15 cm.). Janusauskaite et al., (2013) demonstrated that bacteria and fungi decreased in no tillage system by 25.5 and 22.7%, respectively in comparison to conventional tillage. It can be concluded that conventional tillage system provides stimulating effects for microbial growth due to uniformly distributed residues in the arable layer and increases the rate of supplied oxygen to soil micro sites. The data related to total bacterial population in rice-chickpea cropping sequence revealed that among the different weed management practices, one hand weeding at 20 DAS was found effective to increase bacterial population superior over other treatments under study. These observations are in close agreement with Singh (1990) who reported that population of bacteria were affected with pre and post emergence application of herbicides and these adverse effects gradually reduced with passage of time. Sebiomo et al., (2010) who found that the herbicide treatments had significant effect on percent organic matter of the soils treated with herbicides, which reduced significantly as compared to control. The total bacterial population in rhizosphere soil of chickpea found significantly lower in herbicide treated plots compared to hand weeded and weedy check plots in all the growth period of crop. Table.1 Effect of tillage practices and weed control measures on total bacterial population (X 107 g-1 soil) of rhizosphere soil at different growth stages of chickpea after harvest of rice Treatments 20102011 Main Plot: Tillage management T1: Conventional T2: Minimum T3: Zero S Em + CD (P = 0.05) Sub Plot: Weed management W1: Pendimethalin @ 1000 g/ha PE W2: Imazethapyr @ 80 g/ha PE W3: Imazethapyr @ 90 g/ha PE W4: Imazethapyr @ 100 g/ha PE W5: Imazethapyr @ 70 g/ha POE W6: Imazethapyr @ 80 g/ha POE W7: Imazethapyr @ 90 g/ha POE W8: One hand weeding at 20 DAS W9: Weedy Check S Em + CD (P = 0.05) Days after sowing At Initial At harvest 2011Mean 20102011Mean 2012 2011 2012 0.708 0.667 0.582 0.043 NS 0.344 0.331 0.328 0.005 NS 0.526 0.499 0.455 2.379 2.360 2.355 0.030 NS 1.228 1.124 1.015 0.060 NS 1.804 1.742 1.685 0.650 0.654 0.656 0.650 0.657 0.659 0.647 0.650 0.652 0.074 NS 0.403 0.463 0.304 0.250 0.312 0.176 0.143 0.476 0.483 0.098 NS 0.527 0.559 0.480 0.450 0.485 0.418 0.395 0.563 0.568 2.278 2.331 2.234 2.178 2.424 2.314 2.144 2.638 2.644 0.175 NS 1.160 1.183 1.177 1.161 1.150 0.998 0.888 1.163 1.220 0.175 NS 1.719 1.757 1.706 1.670 1.787 1.656 1.516 1.901 1.932 2849 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 Table.2 Nitrogen uptake by chickpea after harvest of rice as influenced by different tillage and weed management practices N Uptake (Kg ha-1) Treatments Main Plot: Tillage management T1: Conventional T2: Minimum T3: Zero S Em + CD (P = 0.05) Sub Plot: Weed management W1: Pendimethalin @ 1000 g/ha PE W2: Imazethapyr @ 80 g/ha PE W3: Imazethapyr @ 90 g/ha PE W4: Imazethapyr @ 100 g/ha PE W5: Imazethapyr @ 70 g/ha POE W6: Imazethapyr @ 80 g/ha POE W7: Imazethapyr @ 90 g/ha POE W8: One hand weeding at 20 DAS W9: Weedy Check S Em + CD (P = 0.05) 2010-2011 Crop 2011-2012 31.17 28.61 25.33 0.94 3.71 28.14 25.59 22.66 0.94 3.71 29.66 27.10 23.99 26.83 24.62 26.47 29.58 30.48 32.01 33.22 35.52 16.58 1.54 4.37 24.48 22.15 23.79 26.47 27.36 28.72 29.72 31.59 14.90 1.54 4.37 25.66 29.39 25.13 28.03 28.92 30.37 31.47 33.56 15.74 2850 Mean 2010-2011 weed 2011-2012 Mean 34.98 32.45 33.72 33.02 30.90 1.02 4.01 29.88 27.53 1.22 4.78 31.45 29.21 31.09 30.25 32.37 34.40 35.74 34.30 33.65 18.12 46.77 1.42 4.03 29.46 27.66 29.67 31.35 32.46 30.65 28.74 16.38 43.20 1.46 4.16 30.28 28.96 31.02 32.88 34.10 32.48 31.19 17.25 44.99 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 Table.3 Number of nodules plant-1 of chickpea after the harvest of rice at different growth stages as influenced by Different tillage and weed management practices Treatments 20102011 20 DAS 20112012 Main Plot: Tillage management T1: Conventional T2: Minimum T3: Zero 11.06 10.44 10.23 9.08 8.53 8.37 S Em + CD (P = 0.05) 0.37 1.44 0.35 1.37 Sub Plot: Weed management W1: Pendimethalin @ 1000 g/ha PE W2: Imazethapyr @ 80 g/ha PE W3: Imazethapyr @ 90 g/ha PE W4: Imazethapyr @ 100 g/ha PE W5: Imazethapyr @ 70 g/ha POE W6: Imazethapyr @ 80 g/ha POE W7: Imazethapyr @ 90 g/ha POE W8: One hand weeding at 20 DAS W9: Weedy Check S Em + CD (P = 0.05) 10.04 8.58 9.64 10.02 10.44 11.06 11.50 11.80 12.12 0.58 1.65 8.32 7.86 7.89 8.30 8.54 9.12 9.27 9.31 9.34 0.59 1.68 Mean 20102011 40 DAS 20112012 10.07 9.49 9.30 23.41 21.82 20.82 20.26 18.28 16.72 0.59 2.35 0.51 1.99 18.92 18.68 19.76 21.26 23.90 24.98 26.60 29.48 14.58 0.94 2.67 16.36 14.65 17.89 18.89 20.26 20.81 21.59 23.18 12.51 0.66 1.87 9.18 8.22 8.77 9.16 9.49 10.09 10.39 10.56 10.73 2851 Mean 21.84 20.05 18.77 17.64 16.67 18.83 20.08 22.08 22.90 24.10 26.33 13.55 20102011 60 DAS 20112012 Mean 32.24 30.43 29.39 30.09 27.85 25.80 31.17 29.14 27.60 0.64 2.51 0.97 3.81 27.64 26.49 28.09 30.04 32.53 34.76 35.82 40.98 19.82 1.00 2.84 24.24 22.64 25.84 28.56 29.44 32.61 33.75 36.52 17.60 1.20 3.41 25.94 24.57 26.97 29.30 30.99 33.69 34.79 38.75 18.71 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 Table.4 Effect of tillage practices and weed control measures on Basal soil respiration (mg CO2/h/100g soil) Of rhizosphere soil at different growth stages of chickpea after harvest of rice Treatments Days after sowing 10 30 50 At harvest 2010- 2011- Mean 2010- 2011- Mean 2010- 2011- Mean 2010- 2011- Mean 2011 2012 2011 2012 2011 2012 2011 2012 Main Plot: Tillage management T1: Conventional T2: Minimum T3: Zero S Em + CD (P = 0.05) Sub Plot: Weed management W1: Pendimethalin @ 1000 g/ha PE W2: Imazethapyr @ 80 g/ha PE W3: Imazethapyr @ 90 g/ha PE W4: Imazethapyr @ 100 g/ha PE W5: Imazethapyr @ 70 g/ha POE W6: Imazethapyr @ 80 g/ha POE W7: Imazethapyr @ 90 g/ha POE W8: One hand weeding at 20 DAS W9: Weedy Check S Em + CD (P = 0.05) 0.243 0.226 0.208 0.002 0.01 0.238 0.221 0.202 0.006 0.02 0.241 0.224 0.205 0.339 0.319 0.299 0.009 0.03 0.294 0.288 0.276 0.009 0.03 0.317 0.304 0.288 0.310 0.296 0.277 0.009 NS 0.300 0.286 0.267 0.009 NS 0.305 0.291 0.272 0.212 0.210 0.204 0.002 NS 0.206 0.204 0.200 0.002 NS 0.209 0.207 0.202 0.151 0.165 0.149 0.146 0.299 0.293 0.233 0.294 0.298 0.004 0.01 0.139 0.151 0.144 0.141 0.288 0.281 0.271 0.285 0.286 0.009 0.03 0.145 0.158 0.147 0.144 0.294 0.287 0.252 0.290 0.292 0.329 0.335 0.328 0.321 0.296 0.288 0.281 0.344 0.349 0.013 0.04 0.295 0.300 0.293 0.290 0.263 0.256 0.250 0.310 0.318 0.013 0.04 0.312 0.318 0.311 0.306 0.280 0.272 0.266 0.327 0.334 0.404 0.411 0.399 0.387 0.195 0.194 0.196 0.217 0.244 0.014 0.04 0.394 0.399 0.389 0.375 0.194 0.185 0.184 0.205 0.233 0.014 0.04 0.399 0.405 0.394 0.381 0.195 0.190 0.190 0.211 0.239 0.212 0.215 0.212 0.208 0.198 0.195 0.193 0.220 0.225 0.004 NS 0.207 0.210 0.206 0.204 0.193 0.190 0.188 0.213 0.218 0.004 NS 0.210 0.213 0.209 0.206 0.196 0.193 0.191 0.217 0.222 2852 Int.J.Curr.Microbiol.App.Sci (2017) 6(6): 2844-2857 Table.5 Effect of tillage practices and weed control measures on Dehydrogenase activity (µg TPF/h/g soil) Of rhizosphere soil at different growth stages of chickpea after harvest of rice Treatments Days after sowing 10 30 50 At harvest 2010- 2011- Mean 2010- 2011- Mean 2010- 2011- Mean 2010- 2011- Mean 2011 2012 2011 2012 2011 2012 2011 2012 Main Plot: Tillage management T1: Conventional T2: Minimum T3: Zero S Em + CD (P = 0.05) Sub Plot: Weed management W1: Pendimethalin @ 1000 g/ha PE W2: Imazethapyr @ 80 g/ha PE W3: Imazethapyr @ 90 g/ha PE W4: Imazethapyr @ 100 g/ha PE W5: Imazethapyr @ 70 g/ha POE W6: Imazethapyr @ 80 g/ha POE W7: Imazethapyr @ 90 g/ha POE W8: One hand weeding at 20 DAS W9: Weedy Check S Em + CD (P = 0.05) 12.76 10.73 10.74 8.71 8.77 6.72 0.28 0.22 1.09 0.87 11.75 9.73 7.75 32.53 30.47 30.56 28.44 28.56 26.46 1.08 1.01 4.24 3.97 31.50 29.50 27.51 55.76 52.10 53.54 50.21 52.87 49.10 1.66 0.84 NS NS 53.93 51.88 50.99 29.42 25.74 28.31 25.66 26.25 24.52 0.81 0.31 NS NS 27.58 26.99 25.39 9.34 10.36 8.03 8.00 12.20 12.22 12.21 12.22 12.22 0.46 1.32 8.26 9.35 7.10 7.05 11.16 11.19 11.18 11.18 11.19 26.45 27.42 25.31 23.47 12.14 10.06 8.14 68.83 73.13 1.62 4.62 25.33 26.37 24.23 22.37 11.12 9.70 7.68 67.00 71.75 72.15 75.09 71.53 68.17 11.14 9.61 7.75 79.73 91.31 2.65 7.53 70.54 73.47 69.11 64.50 10.18 9.05 7.06 77.28 89.17 2.02 29.06 30.96 28.88 27.89 25.08 22.03 21.14 32.78 34.11 1.25 NS 29.04 29.56 27.43 26.46 23.76 20.66 20.04 30.88 32.06 7.17 8.34 6.16 6.09 10.12 10.16 10.15 10.14 10.15 0.38 1.08 2853 24.21 25.32 23.14 21.27 10.10 9.34 7.21 65.16 70.36 1.53 4.36 68.93 71.84 66.69 60.83 9.21 8.49 6.36 74.83 87.03 1.38 3.91 29.02 28.15 25.98 25.02 22.44 19.28 18.93 28.97 30.01 0.54 NS