Evaluation of Pre-emergence Herbicides and Hand Weeding on Weed Control Efficiency and Performance of Transplanted Early Ahu (Boro) Rice

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1 J. Agric. Technol., 1(1): (2014) ISSN: Evaluation of Pre-emergence Herbicides and Hand Weeding on Weed Control Efficiency and Performance of Transplanted Early Ahu (Boro) Rice Teekam Singh 1, B.S. Satapathy 2, K.B. Pun 3 and S. Lenka 4 1,2,3,4 Regional Rain-fed Lowland Rice Research Station, Gerua, Kamrup, Assam tiku_agron@yahoo.co.in A field experiment was carried out during early Ahu/Boro season of at the research farm of Regional Rainfed Lowland Rice Research Station, Gerua, Hajo, Assam, to evaluate the performance of transplanted rice under pre-emergence herbicides and hand weeding techniques. The treatment consist of seven weed management techniques viz., W1= 1.5 kg ai/ha, W2 = 1.0 kg ai/ha kg ai/ha, W3 = Bensulfuron methyl 0.6% + Pretilachlor 6% 10.0 kg/ha, W4 = Chlorimuron + Metsulfuron-methyl 20 4 g ai/ha, W5 = Pyrazosulfuron 30g ai/ha, W6 = Two hand weeding at 25 and 50 days after transplanting, W7 = Weedy check (control). The highest grain yield (7.2 t/ha) was obtained from W6 (two hand weedings) as a result of reduced dry weight of weeds and higher values of yield components. This was statistically at par with pre-emergence application of Pyrazosulfuron ethyl (6.7 t/ha) and ready mix Chlorimuron + Metsulfuron methyl (6.2 t/ha). The highest net return (`53950/ha) and B:C (2.39) was also obtained with two hand weedings followed by Pyrazosulfuron ethyl and Chlorimuron + Metsulfuron methyl application. Keywords: Rice, Pre-emergence Herbicides, Hand Weeding, Weed Density, Weed Dry Weight, Weed Control Efficiency, Weed index INTRODUCTION Weeds are often called out of place. They are unwanted, prolific, competitive, and often harmful to the crop ecology. They occur every field of rice (Oryza sativa L.) in the world which is the vital food for more than two billion people in Asia and four hundreds of millions of people in Africa and Latin America (IRRI, 2006). Among cereals, rice has been staple food for more than 60 per cent of the world population, providing energy to about 40% of the world population where every third person on earth consumes rice every day in one form or other. In India, it is cultivated on area of 44.0 million hectares with an annual production of million tons in India with productivity of 2.37 t/ha (GOI, 2012). This average productivity of rice is almost less than 50% of the world average rice grain yield. There are several reasons for its low productivity but the infestation of weeds is one of the most important causes for low yield of rice in India. Uncontrolled weed growth caused 33 45% reduction in the grain yield of rice (Manhas et al., 2012). Weeds are responsible for heavy yield losses in rice, to the extent of complete crop failure under severe infestation conditions. Irrespective of the method of rice establishment, weeds are a major impediment to rice production due to their ability to compete for resources. In general, weeds problem in transplanted rice is lower than that of direct seeded rice because of puddling and stagnation of water in transplanted rice during early growth stage of crop. But in some cases where continuous standing water cannot be maintained particularly for the first 45 days, weed infestation in transplanted paddy also may be as high as direct seeded rice. According to Singh et al. (2005) weeds can reduce the grain yield of dry-seeded rice (DSR) by 75.8%, wet seeded rice (WSR) by 70.6% and transplanted rice (TPR) by 62.6%. Weeds by virtue of their high adaptability and faster growth dominate the crop habitat and reduce the yield potential. The degree of competition between the crop and weeds mainly depends on crop factors such as cultivars, crop density, 52

2 Evaluation of Pre-emergence Herbicides and Hand Weeding on Weed Control Efficiency crop age, plant spacing etc. The presently cultivated dwarf high yielding variety with erect leaf canopy promote more weed growth and suffers from yield losses relatively more than the tall traditional varieties of paddy even under transplanted condition. Manual weeding and sometime Butachlor and Pretilachlor herbicides presently used for weed control in transplanted rice. Manual weeding becomes too costly while Butachlor and Pretilachlor provide effective weed control against annual grasses, but not sedges and broad leaf weeds which causes heavy yield reduction of rice. At present many low volumes pre-emergence herbicides are very effective against all type of weed flora in rice field. Keeping above facts in view, the present study was carried out to evaluate the performance transplanted early Ahu/ Boro rice under pre-emergence herbicides and hand weeding techniques. MATERIALS AND METHODS Field experiment was carried out during early Ahu/Boro season of at the research farm of Regional Rainfed Lowland Rice Research Station, Gerua, Hajo, Assam which is located at N latitude, E longitudes and at an altitude of 49 m above mean sea level and characterized in the long-term by sub tropical monsoon type climate with annual average rainfall 1500 mm. The soil was clay loam texture, having ph of 6.2, high in organic carbon (1.07%), medium in available nitrogen (290 kg/ha), high in available P 2 O 5 (37 kg/ha) and medium in available potash (320 kg/ha). The experiment was carried out with seven weed management treatments viz., W1= 1.5 kg ai/ha, W2 = 1.0 kg ai/ha kg ai/ha, W3 = Bensulfuron methyl 0.6% + Pretilachlor 6% 10.0 kg/ha, W4 = Chlorimuron + Metsulfuron-methyl 20 4 g ai/ha, W5 = Pyrazosulfuron 30g ai/ha, W6 = Two hand weeding at 25 and 50 days after transplanting, W7 = Weedy check (control). These seven treatments were replicated thrice and laid out in randomized block design (RBD). The rice variety CR Dhan 601 was used in the study. A common package of practice was followed for raising seedling in seed bed to harvest of the crop. Seedlings of 45 days old were uprooted from the nursery beds carefully and transplanted on 15 th February according to the treatments in the well-puddled experimental plots with spacing of 20 cm 15 cm. A fertilizer dose of kg ha -1 of N-P 2 O 5 -K 2 O was applied as urea, di-ammonium phosphate (DAP) and muriate of potash (MOP) in the field. One-third urea and full dose of DAP and three fourth of MOP were applied as basal dose at the time of final land preparation and incorporated well into the soil. Remaining two-third of urea was applied in two equal splits at 40 and 70 days after transplanting (DAT) while one fourth MOP was applied at panicle initiation. Pre-emergence herbicides were applied at 4 DAT as per treatments while 2 4 D in one of the treatment was applied 35 DAT. All other agronomic practices were kept normal and uniform for all the treatments of the experiment. Data on weeds were recorded at 45 and 90 days after transplanting. Dry weights of weeds were taken by drying them in electric oven at 60 C for 72 hours followed by weighing by digital balance. Weed control efficiency (WCE) and weed Index (WI) were calculated as follows: Weed Control Efficiency (WCE) = DWC-DWT DWC X 100 Where, DWC is the dry weight of weeds in weedy check plots and DWT is the dry weight of weeds in treated plots. W Weed Index (WI) = YHW-Y YHW X 100 Where, YHW is the average yield of hand weeded plot and Y is the average yield of treatment plots. Ten samples hills were collected from each plot for collection of data on plant characters and yield components. The grain and straw weights for each plot were recorded after proper sun drying and adjusted at 12% moisture level then converted into t/ha. The data were subjected to analysis of variance (ANOVA) in RBD for various observations (Gomez and Gomez, 1984). The results were presented at 5% level of significance (P = 0.05) 53

3 Journal of Agriculture and Technology and critical difference (CD) values were calculated to compare the various treatments mean. Economics were computed using the prevailing market price of inputs such as Bensulfuron methyl 0.6% + Pretilachlor 6% 180/kg, Pyrazosulfuron ethyl 700/200g, 2, 4 D Na 340/kg, Chlorimuron + Metsulfuron-methyl /4g a.i., labour 200/ man day and out puts viz., rice 11.80/kg and straw 1/kg. RESULTS AND DISCUSSION Weed Density and Weed Dry Weight Weed density and dry weight were however significantly affected by the weeding treatment (Table 1 & Fig. 1). Herbicide application drastically reduced the weed population and weed dry weight. Weed densities and dry weight were highest in unweeded control plots at both 45 and 90 DAT. Among the treatments, W6 (hand weeding) and W5 (Pyrazosulfuron ethyl) gave 100% weed control at 45 DAT while Chlorimuron + Metsulfuron methyl and Bensulfuron methyl + Pretilachlor had long persistence which resulted low weed densities and dry weight. Weed density and dry weight were highest at 45 DAT and decreased in later stages due to their completion of life cycle and smothering effect of crop plants. Parthipan et al. (2013) and Hasanuzzaman et al. (2009) also reported similar results with herbicides application in rice. Weed Control Efficiency and Weed index Two hand weedings and Pyrazosulfuron ethyl recorded highest weed control efficiency (100%) at 45 DAT while Bensulfuron methyl + Pretilachlor recorded highest weed control efficiency (94.7%) followed by Chlorimuron + Metsulfuron methyl (93.4%), two hand weeding (89%) and Pyrazosulfuron ethyl (83.7%) at 90 DAT. At later stage the treatments showed lower efficiency which might be due to emergence of some new weed species at later stage. These results were partially supported Hassanuzzaman et al. (2009) and Parthipan et al. (2013). Pyrazosulfuron ethyl recorded lowest weed index followed by W4, W3 and W2 which suggest that these treatment had positive correlation in respect to grain yield of rice W1 W2 W3 W4 W5 W6 W7 45 DAT 90 DAT Fig. 1: Weed Density in Rice under Different Weed Control Methods Yield and Yield Attributes Yield attributes and yield of transplanted rice were significantly influenced by the weed control treatments (Table 2). The higher values of effective bearing tillers/hill, panicle length and panicle weight were recorded with two hand weedings followed by Pyrazosulfuron ethyl, Chlorimuron + Metsulfuron methyl and Bensulfuron methyl and Pretilachlor which resulted significantly higher grain and straw yield. The higher values of yield attribute showed the compatibility of these herbicides and effectiveness against weed in rice field. The maximum yield of 7.2 t/ha was recorded with two hand weedings. Similar results were also reported by Deepthi Kiran and Subramanyam (2010) and Parthipan et al. (2013). Superiority of two hand weeding ascribed to absence of weed competition due to complete removal of weeds from the field hence better crop growth. No doubt about the results of two hand weeding are appreciably better in terms of effective weed control and grain yield, but it is time consuming, laborious and presently too costly, it cannot be recommended for large scale. 54

4 Evaluation of Pre-emergence Herbicides and Hand Weeding on Weed Control Efficiency Table 1: Weed Density, Dry Matter Accumulation, Weed Control Efficiency and Weed Index as Influenced by Different Weed Control Techniques Treatment Weed Density (m 2 ) Weed Dry Weight (g/m 2 ) Weed Control Efficiency (%) Weed Index 45 DAT 90 DAT 45 DAT 90 DAT 45 DAT 90 DAT Butachlor Butachlor D Bensulfuron methyl+pretilachlor Chlorimuron + Metsulfuron methyl Pyrazosulfuron ethyl Weed free Control CD (P = 0.05) Table 2: Yield and Yield Attributes as Influenced by Different Weed Control Techniques Treatment Effective Tillers/ Hill Filled Grains/ Length (cm) Weight (g) Straw Yield (t/ha) Grain Yield (t/ha) Harvest Index Butachlor Butachlor D Bensulfuron methyl+pretilachlor Chlorimuron + Metsulfuron methyl Pyrazosulfuron ethyl Two hand weedings (25&50 DAT) Control CD (P = 0.05) NS Grain yield recorded with all pre-emergence herbicides were significantly superior over unweeded control plot. Grain yield from Pyrazosulfuron ethyl (6.7 t/ha) and ready mix Chlorimuron + Metsulfuron methyl (6.2 t/ha) was found statistically at par with two hand weedings. Higher grain yield under these treatments might be due to higher values of yield attributes over Butachlor and Bensulfuron methyl + Pretilachlor. Similar findings with pre-emergence herbicides were also reported by Nalini et al. (2012) and Kishore Jalindar et al. (2012). Weeds in unweeded control plots caused 33.3% reduction in the grain yield. B:C due to maximum labour requirement followed by treatment W3 (Bensulfuron methyl + Pretilachlor), W2 (Butachlor D) needed ` and ` 38060/ha which may be due to high volume of herbicide and labour cost. On the other hand application of pre-emergence Pyrazosulfuron ethyl alone showed at par economic benefits compared to hand weeding. Similar results on the weed control costs were as also observed by Hasanuzzaman et al. (2009). The highest net return and B:C was obtained with two hand weedings followed by Pyrazosulfuron ethyl and Chlorimuron + Metsulfuron methyl application in Ahu/ Boro rice. Economics Different weed control methods involved different amounts of cost which affect the total cost of cultivation, Net returns and B: C of Ahu/Boro rice (Fig. 2). The hand wedding is laborious and generally more expensive. From the computation of weed control cost it was observed that the maximum cost of weed control (` 38910/ha) was required for the treatment W6 (two hand weedings) which was W1 W2 W3 W4 W5 W6 W7 Cost of production Net Return Fig. 2: Cost of Production and Net Returns under Different Weed Control Methods 55

5 Journal of Agriculture and Technology REFERENCES Deepthi Kiran Y., Subramanyam Performance of pre and post emergence herbicides on weed flora and yield of transplanted rice (Oryza sativa). Indian J. Weed Sci. 42: GOI Ministry of Finance, Government of India. Economic Survey pp. A Gomez K.A., Gomez A.A Statistical Producers for Agricultural Research. 2 nd Edition, John Wiley and Sons Incorporation, New York. Hasanuzzaman M., Ali M.H., Alam M.M., Akther M., Alam K.F Evaluation of pre-emergence herbicide and hand weeding on the weed control efficiency and performance of transplanted aus rice. American-Eurasian J Agron. 2(3): IRRI World Rice Statistics. International Rice Research Institute, Kishor Jalindar M., Lourduraj A.C., Arthanari P.M., Chinnusamy C Herbicidal weed management in transplanted rice. Proceedings of the Biennial Conference of Indian Society of Weed Science on Weed Threat to Agriculture, Biodiversity and Environment, April 19 20, 2012, Thrissur, Kerala, India. pp. 92. Manhas SS, Singh G., Singh D., Khajuria V Effect of tank mixed herbicides on weeds and transplanted rice (Oryza sativa L). Annals Agril Res New Series. 33: Nalini K., Arthanari P.M., Chinnusamy C Early post emergence herbicidal weed management in transplanted rice. Proceedings of the Biennial Conference of Indian Society of Weed Science on Weed Threat to Agriculture, Biodiversity and Environment, April 19 20, 2012, Thrissur, Kerala, India. pp. 74. Parthipan T., Ravi V., Subramaniam E., Ramesh T Integrated Weed Management on growth and yield of transplanted rice and its residual effect on succeeding black gram. J Agron. 12(2): Singh S, Singh G., Singh V.P., Singh A.P Effect of establishment methods and weed management practices on weeds and rice in rice-wheat cropping system. Indian J. Weed Sci. 37: