Bangladesh Agron. J. 2019, 22 (1): 57-69 EFFECT OF WATER, NUTRIENT AND WEED MANAGEMENT ON THE YIELD AND QUALITY OF AROMATIC BORO RICE (CV. BRRI dhan50) S.K. Paul*, M.C. Ray, M.A.R. Sarkar and S.K. Sarkar Department of Agronomy, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh *Corresponding E-mail: skpaul@bau.edu.bd (Received: 25 April 2019, Accepted: 30 July 2019) Keywords: Yield, grain protein, aromatic Bororice Abstract An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during January to June 2016 to observe the effect of water, nutrient and weed management practices on the yield and quality of aromatic Boro rice (cv. BRRI dhan50). The experiment consisted of three water managements viz. conventional flood irrigation, AWD (Alternate Wetting and Drying) and SRI (System of Rice Intensification); two nutrient managements viz. recommended dose of inorganic fertilizers (Urea, TSP, MoP, Gypsum, ZnSO4 @ 250, 120, 120, 100, 10 Kg ha -1, respectively) and 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1; and three weed managements viz. weedy check (control), two hand weeding at 20 and 40 DAT, and pre-emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast klin 10WP) application. The highest number of effective tillers hill-1, grains panicle-1,grain yield and protein (%) in grain were obtained in SRI water management which was followed by AWD and conventional flood irrigation. Between the two nutrient management practices, application of 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 produced higher number of effective tillers hill-1,grains panicle-1,1000-grain weight, grain yield and protein (%) in grain than in organic fertilizer. Among the weed management practices, application of pre-emergence herbicide (Rifit 33EC) followed by post-emergence herbicide (Fast Klin 10WP) produced the highest number of effective tillers hill-1,grains panicle- 1,1000-grain weight, grain yield and protein (%) in grain followed by two weedings at 20 and 40 DAT while the lowest grain yield was obtained in weedy check. The highest number of effective tillers hill-1,grains panicle- 1, grain yield and protein (%) in grain was found in SRI water management combined with 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 and application of pre- emergence herbicide followed by post-emergence herbicide. So, it may be concluded that, to get the highest grain yield in aromatic Boro rice, SRI method along with application of 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 and applying pre- emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast Klin 10WP) could be recommended. Introduction Rice (Oryza sativa) is the most extensively cultivated cereal crop in Bangladesh. Aromatic rice contributes a small portion (10%) but an important subgroup of rice production. In recent years, aromatic rice has been introduced to the global market because of its taste, deliciousness and high price (Adhikari et al., 2018). The yield of fine rice is lower than that of coarse and about:blank 58 Paul et al. medium rice varieties. To overcome this situation increment of aromatic rice production unit-1 area is the only alternative to bring self-sufficiency in aromatic rice through intensive care, management and adoption of new technologies. IRRI has developed AWD (Alternate Wetting and Drying) technology. This system can save 30% irrigation water, save energy and fuel consumption. AWD requires irrigation when the water level goes down to 15 cm below the soil surface. SRI (System of rice intensification) is another water saving technology (Stool et al., 2002) where minimum water input with intermittent or saturated soil requires 20- 50% less water (Lek and Yongyod, 1989) than continuous flooding. In recent years there has been serious concern about long-term adverse effect of continuous and indiscriminate use of inorganic fertilizers on deterioration of soil structure, soil health and environmental pollution (Ghosh and Bhat, 1998). Combined application of manure with inorganic fertilizers increased grain yield and protein content of aromatic rice (Sarkar et al., 2014, Roy et al., 2015; Pal et al., 2016; Biswas et al., 2016 and Marzia et al., 2016). High competitive ability of weeds exerts a serious negative effect on crop production causing significant losses in crop yield. Yield losses due to weed infestation are greater than the combined losses of insect pests and diseases. In Bangladesh, weed infestation reduces the grain yield 70-80% in Aus rice, 30-40% for transplanted Aman rice and 22-36% for modern Boro rice cultivars (Mamun, 1990). In case of aromatic rice grain yield was reduced by 28.16% in Binadhan-9 in Aman season (Zannat et al., 2014) whereas by 59.82% in BRRI dhan50 at Boro season (Sinha et al., 2018) due to weed infestation. Herbicides are effective in controlling weeds alone or in combination with hand weeding (Ahmed et al., 2005). Herbicides in combination with hand weeding would help to obtain higher crop yield with less efforts and cost (Prasad and Rafy, 1995; Sathyamoorthy et al., 2004). So, the present study was undertaken to find out the effect of water, nutrient and weed management on the growth, yield and quality of aromatic Bororice (cv. BRRI dhan50). Materials and Methods The experiment was carried out at the Agronomy Field Laboratory of Bangladesh Agricultural University, Mymensingh during January to June 2016 to study the effect of water, nutrient and weed management practices on the performance of aromatic Boro rice. The experimental field was located at 24o°75'N latitude and 90o°50'E longitude at an elevation of 18m above the mean sea level. The experimental area belongs to non-calcareous dark grey floodplain soil under the Sonatola soil series of Old Brahmaputra Floodplain in Agro Ecological Zone (AEZ- 9) (UNDP and FAO, 1988). The experimental field was medium high, fairly leveled with well drained soils. The soils of this series are pre-dominantly silty loam, dark grey in color having pH 6.5 and low in organic matter. The experiment comprised three water management viz. Conventional flood irrigation - (I1), AWD (Alternate wetting and drying) - (I2) and SRI (System of rice intensification) - (I3); two levels of nutrient management viz. Recommended dose of inorganic fertilizer (Urea, TSP, MoP, Gypsum, ZnSO4 @ 250, 120, 120, 100, 10 kg ha-1 respectively) - (F1) and 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 - (F2), and there levels of weed management viz. weedy check (control) - (W0),two hand weedings at 20 and 40 (Days after transplanting) DAT - (W1) and application of Pre-emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast Klin 10WP) (W2). The experiment was laid out in a randomized complete block design with three replications. Eachunit plot size was 4.0 m × 2.5m. The rice var. BRRI Effect of Water, Nutrient and Weed Management 59 dhan50 of aromatic Boro rice was used as the test crop. Sprouted seeds were sown in the nursery bed on 13 December 2015 for AWD and continuous flooding practices. In SRI method seeds were sown in 11 January 2016. The experimental plots were fertilized with as per experimental treatments. The entire amounts of triple super phosphate, muriate of potash, gypsum and zinc sulphate and poultry manure were applied at final land preparation. Urea was applied in three equal installments at 15, 30 and 45 DAT. The seedlings were uprooted on 26 January 2016 without causing much mechanical injury to the roots and they were immediately transplanted in the well puddled main fieldat the rate of two seedlings hill-1, maintaining row and hill distance of 25 cm and 15 cm in AWD and Conventional flooding systems. In case of SRI, single seedling hill-1 was used12-day old seedlings whereas conventional and AWD systems 30-day old seedlings were used. AWD is monitored the depth of irrigated water on the field using a ‘field water tube’ or magic pipe. It involves installation of a perforated pipe in the rice field to allow observation of water level. In this experiment, magic pipe was installed at 10 DAT. After irrigation, the depth of irrigation water will gradually decrease. When the irrigation water has dropped to 15 cm below the surface of the soil, irrigation was applied with 5 cm depth water. From one week before to one week after flowering, irrigation water was kept at 5 cm depth. After flowering, the water level was dropped again to 15 cm below the surface before irrigation. Water management was the most complicated variable in SRI method where rice crops are kept unflooded during vegetative growth with partial amount of water was applied to keep the soil moist.It was even allowed to dry out for 2 to 4 days during tillering to keep the soil well aerated and to allow better root growth. From panicle initiation (PI) to hard dough stage, a thin layer of water (2-3 cm) was kept on the plots. Again water was drained out from the plots during ripening stage. Data on weed population were recorded from each plot at 65 DAT by using 1 m2 quadrate as per method described by Cruz et al. (1986). The weeds inside each quadrate were uprooted and cleaned, separated species-wise and dried first in the sun and then in an electrical oven for 72 hours at a temperature of 80 oC followed by weed dry weight of each plot was recorded by an electrical balance. The crop was harvested on 25 May, 30 May and 06 June 2016, respectively for conventional, AWD and SRI. The grains were cleaned and finally the weight was adjusted to a moisture content of 14%. The straw was sun dried and the yields of grain and straw plot-1 were recorded and converted to t ha-1. Harvest index indicates the ratio of economic yield (grain yield) to biological yield (grain yield + straw yield) and was calculated by the following formula: Harvest index (%) = ×x 100. Estimation of protein in grains was done by following Micro-Kjeldahl Method. Oven dried rice kernels were then put in polythene bags and kept in desiccators for subsequent chemical analysis for estimation of protein. Protein content (%) was estimated by Micro-Kjeldahl method (AOAC, 1984) at the Agri-Varsity Humboldt Soil Testing Laboratory of Soil Science Department, Bangladesh Agricultural University, Mymensingh. The recorded data were compiled and tabulated for statistical analysis. Analysis of variance was done with the help of computer package, MSTAT. The mean differences among the treatments were adjudged by Duncan’s Multiple Range Test (Gomez and Gomez, 1984). 60 Paul et al. Results and Discussion Weed dry weight There was significant effect on total weed dry weight (g m-2) due to water management (Table 1). The highest total weed dry weight (38.71 g m-2) was found in I1 (Conventional flood irrigation) followed by AWD (Alternate Wetting and Drying), while the lowest total weed dry weight (33.35 g m-2) was found in I3 (SRI) water management (Table 1).There was significant effect on total weed dry weight due to nutrient management (Table 1). Maximum weed dry weight (37.75 g m-2) was found in F1 (Recommended dose of inorganic fertilizer) and minimum one (33.56 g m-2) was found in F2 (25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1) nutrient management (Table 1). There was significant effect on total weed dry weight due to weed management (Table 1). At 65 DAT, the maximum total weed dry weight (75.03 g m-2) was found in W0 (No weeding) followed by two hand weedings at 20 and 40 DAT while the lowest total weed dry weight (8.91 g m-2) in W2 (Pre-emergence herbicide Rifit 33EC followed by post emergence herbicide Fast Klin 10WP) weed management (Table 1).Non-significant variation was found on total weed dry weight due to interaction effect of water and nutrient management at 65 DAT (Table 2). However, numerically, the highest weed dry weight (41.43 g m-2) was found in I1×F1 (Conventional flood irrigation × Recommended dose of inorganic fertilizer) and the lowest (31.35 g m-2) one was found in I3×F2 (SRI × 25% less than recommended dose of inorganic fertilizer + poultry manure) treatment (Table 2). Significant variation was found on total weed dry weight due to interaction effect of water and weed management at 65 DAT (Table 3). The highest weed dry weight (80.48 g m-2) was found in I1×W0 (Conventional flood irrigation × No weeding) followed by I2 × W0 (AWD × No weeding) and I3 × W0 (SRI × No weeding) and the lowest (7.66 g m -2) one was found on I3×W2 (SRI × Pre-emergence herbicide Rifit 33EC followed by post emergence herbicide Fast Klin 10WP) treatment (Table 3).Significant variation was found on total weed dry weight due to interaction effect of nutrient and weed management practices at 65 DAT (Table 4). The highest total weed dry weight (77.74 g m-2) was found in F1×W0 (Recommended dose of inorganic fertilizer × No Weeding) and the lowest (8.692 g m-2) one was found in F1×W2 (Recommended dose of inorganic fertilizer× pre-emergence herbicide Rifit 33EC followed by post- emergence herbicide Fast Klin 10WP) treatment (Table 4). Non-significant variation was found on total weed dry weight due to interaction effect of water, nutrient and weed management practices at 65 DAT (Table 5). Yield and yield components Crop characters, yield contributing characters, yield and grain protein content were significantly influenced by water management except panicle length and 1000-grain weight (Table 1). The tallest plant (82.56 cm), number of total tillers hill-1 (12.25), effective tillers hill-1 (11.07) and grains panicle-1 (119.99) were found in I3 (SRI method) followed by I2 (AWD) and all parameters showed the lowest values in I1 (conventional flood irrigation) (Table 1). While the highest number of non-effective tillers hill-1(1.44) was recorded in AWD (Alternate wetting and drying) and sterile spikelets panicle-1 (16.12) were recorded in I1 (conventional flood irrigation) and the lowest values were found in I3 (SRI). The highest grain yield (5.41 t ha-1) was obtained in I3 (SRI) water management followed by I2 (AWD) and the lowest grain yield (4.80 t ha-1) in I1 (Conventional flood irrigation). The increased yield might be due to the highest number of grains panicle-1 and number of effective tillers hill-1. Straw yield also showed similar trend as that of grain yield. The highest grain protein content (8.54%) was found in I3 Effect of Water, Nutrient and Weed Management 59 (SRI) followed by I2 (AWD) and the lowest grain protein content (7.96%) in I1 (conventional flood irrigation). Table 1. Effect of water management on crop characters, yield components and yield of aromatic Boro rice (cv. BRRI dhan50) Treatments Dry matter of weed (g m-2) Plant height (cm) Total tillers hill-1 (no.) Effective tillers hill-1 (no.) Non- effective tillers hill-1 (no.) Panicle length (cm) Grains panicle-1 (no.) No. of sterile spikelets panicle-1 1000- grain weight (g) Grain yield (t ha-1) Straw yield (t ha-1) Harvest index (%) Grain protein content (%) Water management I1 38.71a 76.96b 10.49b 9.08b 1.41a 21.36 116.11c 16.12a 18.30 4.80c 5.20c 48.00 7.957b I2 34.90b 82.49a 10.92b 9.48b 1.44a 21.64 117.03b 14.11b 18.64 4.99b 5.46b 47.75 8.093b I3 33.35c 82.56a 12.25a 11.07a 1.18b 21.89 119.99a 13.75c 19.32 5.41a 6.05a 47.20 8.536a CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 Nutrient management F1 37.75a 80.69 10.81b 9.40b 1.41a 21.52 114.40b 15.10a 18.41b 4.72b 5.37b 46.78 8.00b F2 33.56b 80.66 11.63a 10.36a 1.28b 21.74 117.68a 14.22b 19.15a 5.03a 5.77a 46.57 8.26a CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 Weed management W0 75.03a 78.81b 9.13c 8.17c 0.96c 21.22 b 116.53 16.50a 18.12b 2.91c 3.80c 43.36c 7.92b W1 23.03b 81.46a 11.62b 9.97b 1.65a 21.57ab 118.05 14.03b 18.50b 5.10b 6.19b 45.17b 8.12b W2 8.91c 81.75a 12.91a 11.50a 1.41b 22.10a 120.55 13.46c 19.64a 5.75a 6.73a 46.07a 8.54a CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 In a column, figures with same letter or without letter do not differ significantly (as per DMRT). I1 = Conventional flood irrigation, I2 = AWD (Alternate Wetting and Drying), I3 = SRI (System of Rice Intensification), F1 = Recommended dose of inorganic fertilizer, F2 = 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha -1, W0 = Weed check (control), W1 = Two hand weeding at 20 and 40 DAT, W2 = Pre-emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast Klin 10WP) All yield contributing characters, yield and grain protein content were significantly influenced by nutrient management except plant height and panicle length (Table 1). The highest number of total tillers hill-1 (11.63), effective tillers hill-1 (10.36), grains panicle-1 (117.68) and 1000-grain weight (19.15 g) were found in all the parameters showed lower values in F1.The highest number of non-effective tillers hill-1 (1.41) and sterile spikelets panicle-1 (15.10) were produced in F1 nutrient management, while the lowest number of sterile spikelets panicle-1 (14.22) in F2 (25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1). Higher grain yield (5.03 t ha-1) and straw yield (5.77 t ha-1) were obtained in F2 (25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1) nutrient management than that of F1.The increased yield might be due to higher number of grains panicle-1, higher 1000-grain weight and higher number of effective tillers hill-1. Application of inorganic fertilizer along with manure greatly influence the grain yield of rice were reported (Islam et al., 2015; Roy et al., 2015; Pal et al., 2016; Biswas et al., 2016 and Sarkar et al., 2016). Table 1 indicates that higher grain protein content (8.26%) was found in F2 compared to F1. Integration of poultry manure with chemical fertilizer increased grain protein content was also reported (Sarkar et al., 2014; Biswas et al., 2016 and Pal et al., 2016) Crop characters, yield contributing characters, yield and grain protein content were significantly influenced by water management except grains panicle-1 (Table 1). The tallest plant (81.75 cm) was found in W2 (pre-emergence herbicide Rifit 33EC followed by post emergence herbicide Fast Klin 10WP) which was at par with W1(two hand weeding at 20 and 40 DAT) while the shortest plant (78.81 cm) was found in W0 (No weeding). The highest number of total tillers hill -1 (12.91), effective tillers hill-1 (11.50), longest panicle (22.10 cm) and the highest weight of 1000-grain (19.64 g) were obtained in W2 whileall the parameters showed intermediate values in W1and the corresponding lowest values in W0. The highest number of non-effective tillers hill-1 (1.65) was produced in W1 while the lowest number of non-effective tillers hill-1 (0.96) in W0. The highest number of sterile spikelets panicle-1 (16.50) was produced in W0 weed management, while the lowest number of sterile spikelets panicle-1 (13.46) in W2. Number of grains panicle-1 was not significantly influenced by different weed management. Table 1 indicates that numerically the highest number of grains panicle-1 (120.55) was produced in W2 while the lowest number of grains panicle -1 (116.53) by W0. The highest grain yield (5.75 t ha-1), straw yield (6.73 t ha-1) and harvest index (46.07%) were produced in W2 followed by W1 while the corresponding lowest values were obtained in W0. Weed infestation reduced 49.39% grain yield over W2. Similar trend was reported by Sinha et al. (2018) that weed reduced grain yield by 59.83% in aromatic Boro rice cv. BRRI dhan50. The highest grain protein content (8.54%) was found in W2 and the lowest grain protein content (7.92%) in W0which was at par with W1. Table 2 indicates that the highest number of total tillers hill-1(12.78), effective tillers hill-1 (11.67), and grain yield (5.19 t ha-1 t ha-1) were obtained in I3 × F2 (SRI × 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1t). Grain yield produced in I3 × F1 (SRI × recommended dose of inorganic fertilizer) was at parinI3 × F2 (SRI-25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 t) while the corresponding lowest values in I1 F1 (conventional flood irrigation × recommended dose of inorganic fertilizer). Table 2. Interaction effect of water and nutrient management on crop characters, yield components and yield aromatic Boro rice (cv. BRRI dhan50) Interaction (Water × nutrient management) Dry matter of weed (g m- 2) Plant height (cm) Total tillers hill-1 (no.) Effective tillers hill-1 (no.) Non- effective tillers hill-1 (no.) Panicle length (cm) Grains panicle- 1 (no.) No. of sterile spikelets panicle-1 1000- grain weight (g) Grain yield (t ha-1) Straw yield (t ha-1) Harvest index (%) Grain protein content (%) I1 × F1 41.43 82.59 10.15c 8.64d 1.52 21.22 113.40 16.89 18.07 4.76c 5.01 48.72 7.58 I1 × F2 35.98 82.54 10.82bc 9.52bc 1.29 21.50 114.82 15.35 18.54 4.92b 5.44 47.49 7.93 I2 × F1 36.43 82.14 10.51bc 9.09c 1.42 21.66 115.10 14.31 18.27 4.80bc 5.28 47.61 7.94 I2 × F2 33.36 82.84 11.32b 9.87bc 1.45 21.63 116.96 13.92 19.00 4.95b 5.65 46.69 8.24 I3 × F1 35.35 77.35 11.74ab 10.47b 1.27 21.67 115.71 14.12 18.87 4.98ab 5.86 45.94 8.48 I3 × F2 31.35 76.58 12.78a 11.67a 1.09 22.10 118.26 13.38 19.77 5.19a 6.24 45.40 8.59 CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 In a column, figures with same letter or without letter do not differ significantly (as per DMRT). I1 = Conventional flood irrigation, I2 = AWD (Alternate Wetting and Drying), I3 = SRI (System of Rice Intensification) F1 = Recommended dose of inorganic fertilizer, F2 = 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha Table 3 indicates that the highest number of grains panicle-1(119.0) was produced in I3 × W2 (SRI × pre-emergence herbicide Rifit 33EC followed by post-emergence herbicide Fast Klin 10WP) which was at par to I2 W2 (AWD pre-emergence herbicide Rifit 33EC followed by post emergence herbicide Fast Klin 10WP). The highest grain yield (6.14 t ha-1) was produced in I3 W2 followed by I3 W2 (SRI two hand weeding at 20 and 40 DAT) (6.14 t ha -1) and the lowest grain yield (2.70 t ha-1) in I1 ×W0 (conventional flood irrigation × no weeding). The highest number of effective tillers hill-1(11.96) was obtained in F2 × W2 (25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 × pre-emergence herbicide Rifit 33EC followed by post-emergence herbicide Fast Klin 10WP) followed by F1×W2 (recommended dose of inorganic fertilizer pre- emergence herbicide Rifit 33EC followed by post emergence herbicide Fast Klin 10WP) and lowest one (7.79) in F1×W0 (recommended dose of inorganic fertilizer no weeding) Table 3. Interaction effect of water and weed management on crop characters, yield components and yield of aromatic Boro rice (cv. BRRI dhan50) In a column, figures with same letter or without letter do not differ significantly (as per DMRT). I1 = Conventional flood irrigation, I2 = AWD (Alternate Wetting and Drying), I3 = SRI (System of Rice Intensification), W0 = Weed check (control), W1 = Two hand weeding at 20 and 40 DAT, W2 = Pre-emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast Klin 10WP) Interaction (Water × weed management) Dry matter of weed (g m-2) Plant height (cm) Total tillers hill-1 (no.) Effective tillers hill-1 (no.) Non- effective tillers hill-1 (no.) Panicle length (cm) Grains panicle-1 (no.) No. of sterile spikelets panicle-1 1000- grain weight (g) Grain yield (t ha-1) Straw yield (t ha-1) Harvest index (%) Grain protein content (%) I1 × W0 80.48a 81.47 8.39 7.40 0.99d 20.87 116.40de 20.10a 17.71 2.70e 3.45 43.90 7.35 I1 × W1 25.80c 83.65 10.88 9.14 1.74ab 21.32 117.00cd 14.53bc 18.12 5.07c 5.81 46.59 7.82 I1 × W2 9.832e 82.57 12.20 10.70 1.50b 21.90 117.93b 13.73cd 19.08 5.43bc 6.35 46.09 8.11 I2 × W0 73.46b 81.15 8.71 7.79 0.91e 21.25 116.58d 14.85b 17.92 2.83de 3.73 43.14 7.83 I2 × W1 22.00d 83.08 11.47 9.54 1.93a 21.60 116.86d 13.96bd 18.40 5.41bc 6.19 46.63 7.99 I2 × W2 9.236e 83.24 12.57 11.11 1.47b 22.08 118.63ab 13.53cd 19.60 5.69b 6.48 46.75 8.46 I3 × W0 71.10b 73.81 10.30 9.31 0.99d 21.55 117.61bc 14.56bc 18.74 3.21d 4.20 43.34 8.28 I3 × W1 21.28d 78.51 12.50 11.23 1.28c 21.80 117.28c 13.59cd 19.00 5.69b 6.58 46.37 8.46 I3 × W2 7.662e 78.57 13.95 12.68 1.27c 22.31 119.0a 13.11d 20.24 6.14a 7.36 45.48 8.87 CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 Table 4. Interaction effect of nutrient and weed management on crop characters, yield components and yield of aromatic Boro rice (cv. BRRI dhan50) Nutrient × weed management Dry matter of weed (g m-2) Plant height (cm) Total tillers hill-1 (no.) Effective tillers hill-1 (no.) Non- effective tillers hill-1 (no.) Panicle length (cm) Grains panicle- 1 (no.) No. of sterile spikelets panicle-1 1000- grain weight (g) Grain yield (t ha- 1) Straw yield (t ha- 1) Harvest index (%) Grain protein content (%) F1 × W0 77.74a 78.87 8.74 7.79ef 0.95c 21.19 107.53 17.12 17.77 2.78 3.58 43.71 7.71 F1 × W1 26.34c 81.85 11.18 9.37d 1.81a 21.44 109.36 14.39 18.16 5.22 5.98 46.60 7.93 F1 × W2 9.128e 81.35 12.49 11.03b 1.46b 21.93 111.31 13.80 19.29 5.60 6.55 46.09 8.36 F2 × W0 72.28b 78.74 9.52 8.54e 0.98c 21.26 111.52 15.87 18.48 3.05 4.02 43.14 7.93 F2 × W1 19.71d 81.65 12.06 10.57c 1.49b 21.71 112.73 13.67 18.84 5.56 6.40 46.48 8.24 F2 × W2 8.692e 81.57 13.32 11.96a 1.37b 22.26 113.78 13.11 19.99 5.90 6.90 46.09 8.59 CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 In a column, figures with same letter or without letter do not differ significantly (as per DMRT). F1 = Recommended dose of inorganic fertilizer, F2 = 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha -1 W0 = Weed check (control), W1 = Two hand weeding at 20 and 40 DAT, W2 = Pre-emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast Klin 10WP) Table 5 indicates that the highest number of total tillers hill-1 (14.58), effective tillers hill-1 (13.40) and grains panicle-1 (118.65) were obtained in I3×F2×W2 (SRI 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha -1 pre- emergence herbicide Rifit 33EC followed by post emergence herbicide Fast Klin 10WP) treatment while the corresponding lowest values in I1F1×W0 (conventional flood irrigation × recommended dose of inorganic fertilizer ×no weeding) treatment. Table 5. Interaction effect of water, nutrient and weed management on crop characters, yield components and yield of aromatic Boro rice (cv. BRRI dhan50) In a column, figures with same letter or without letter do not differ significantly (as per DMRT). I1 = Conventional flood irrigation, I2 = AWD (Alternate Wetting and Drying), I3 = SRI (System of Rice Intensification) F1 = Recommended dose of inorganic fertilizer, F2 = 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha -1 W0 = Weed check (control), W1 = Two hand weeding at 20 and 40 DAT, W2 = Pre-emergence herbicide (Rifit 33EC) followed by post emergence herbicide (Fast Klin 10WP) Interaction (Water × nutrient × weed management) Dry matter of weed (g m-2) Plant height (cm) Total tillers hill-1 (no.) Effective tillers hill-1 (no.) Non- effective tillers hill-1 (no.) Panicle length (cm) Grains panicle-1 (no.) No. of sterile spikelets panicle-1 1000- grain weight (g) Grain yield (t ha-1) Straw yield (t ha- 1) Harvest index (%) Grain protein content (%) I1 × F1 × W0 83.30 81.61 8.11f 7.10i 1.01 20.56 114.17fg 21.43 17.49 2.55h 3.25 43.96 7.23 I1 × F1 × W1 31.04 83.21 10.4d 8.49fg 1.91 21.21 117.17bcde 15.19 17.98 4.78e 5.43 46.81 7.58 I1 × F1 × W2 9.960 82.94 11.98c 10.33cde 1.65 21.89 117.93ab 14.05 18.74 5.25de 6.23 45.73 7.93 I1 × F2 × W0 77.67 81.33 8.67ef 7.70g 0.97 21.18 117.70b 18.76 17.93 2.89g 3.66 44.12 7.47 I1 × F2 × W1 20.56 84.09 11.37cd 9.80de 1.57 21.42 117.83abc 13.87 18.25 5.36cde 6.19 46.40 8.05 I1 × F2 × W2 9.703 82.20 12.42b 11.07bcde 1.35 21.90 117.93ab 13.41 19.42 5.62bc 6.47 46.48 8.28 I2 × F1 × W0 75.52 82.13 8.34efg 7.42gh 0.93 21.59 115.10f 15.02 17.50 2.72gh 3.43 44.22 7.60 I2 × F1 × W1 24.03 82.28 11.01cde 9.03defg 1.98 21.48 115.63def 14.18 18.00 5.29d 6.07 46.56 7.82 I2 × F1 × W2 9.733 82.00 12.18bc 10.82c 1.37 21.92 116.50cde 13.71 19.31 5.49cd 6.35 46.36 8.40 I2 × F2 × W0 71.39 80.16 9.07e 8.17fgh 0.90 20.91 116.00de 14.67 18.34 3.00fgh 4.04 42.61 8.05 I2 × F2 × W1 19.96 83.88 11.93c 10.05d 1.88 21.73 117.00c 13.74 18.79 5.52c 6.30 46.70 8.17 I2 × F 2× W2 8.740 84.48 12.96abc 11.40bcd 1.56 22.24 117.77abd 13.35 19.88 5.88b 6.60 47.12 8.52 I3 × F1 × W0 74.40 72.88 9.77de 8.85f 0.92 21.42 116.33d 14.92 18.31 3.15fg 4.06 43.68 8.28 I3 × F1 × W1 23.95 80.05 12.13bc 10.60cd 1.53 21.63 117.30bcd 13.79 18.50 5.59bc 6.43 46.50 8.40 I3 × F1 × W2 7.690 79.10 13.32ab 11.95b 1.36 21.98 117.50bc 13.64 19.81 6.07ab 7.08 46.15 8.75 I3 × F2 × W0 67.79 74.74 10.83cdef 9.77def 1.07 21.68 116.87cd 14.19 19.16 3.27f 4.35 42.91 8.28 I3 × F2 × W1 18.62 76.97 12.87abcd 11.85bc 1.02 21.98 117.87ab 13.39 19.49 5.80b 6.72 46.32 8.52 I3 × F2 × W2 7.634 78.04 14.58a 13.40a 1.18 22.64 118.65a 12.57 20.67 6.20a 7.64 44.79 8.98 CV (%) 6.44 3.62 7.62 5.17 11.84 4.37 8.19 14.46 4.94 3.86 4.00 3.48 4.18 The highest grain yield (6.20 t ha-1) was obtained in I3×F2×W2 followed by I3×F2×W1 while the lowest grain yield (2.55 t ha -1) was found in I1×F1×W0. Grain protein content was not statistically significant (Table 5). A functional relationship was observed between dry matter weight of weeds (at 65 DAT) and grain yield of aromatic Boro rice (cv. BRRI dhan50). A negative linear relationship between weed dry weight (at 65 DAT) and grain yield of aromatic Boro rice was observed, indicating that higher the weed dry matter value lower the grain yield (Figure 1). The functional relationship adequately described by regression equation Y = -0.0445x + 6.2706 (R² = 0.9714). The functional relationship indicates that 97% of the variation in grain yield could be explained from the variation in weed dry matter production at 65 DAT. This finding is in agreement with that of Sinha et al. (2018) who reported that 89% of Boro rice (cv. BRRI dhan50) yield could be explained by the functional relationship of weed dry matter production at 65 DAT while Islam et al. (2015) reported that 80% of the variation in grain yield could be explained from the variation in weed dry matter production at 60 DAT in BRRI dhan49. Conclusion The highest number of effective tillers hill-1,grains panicle-1, grain yield and protein (%) in grain was found in SRI water management along with 25% less than recommended dose of inorganic fertilizer + poultry manure @ 2.5 t ha-1 and application of pre-emergence herbicide followed by post emergence herbicide. Therefore, it could be concluded that SRI method along with application of 25% less than recommended dose of inorganic fertilizer + poultry @ 2.5 tha-1 and pre-emergence herbicide (Rifit 33EC) followed by post-emergence herbicide y = -0.0445x + 6.2706 R² = 0.9714 0 1 2 3 4 5 6 7 0 20 40 60 80 100 G ra in y ie ld ( t/ h a) Weed dry weight (g/m2) Effect of Water, Nutrient and Weed Management 59 (Fast Klin 10WP) may be recommended for higher grain yield and quality in terms of grain protein content in aromatic Boro rice cv. BRRI dhan50. Acknowledgement The financial assistance of Ministry of Science and Technology, Govt. of the People’s Republic of Bangladesh, to conduct the research project is thankfully acknowledged. References Adhikari, A., M.A.R. Sarkar, S.K. Paul and K.K. Saha. 2018. Impact of nutrient management on the yield performance of some aromatic fine rice (Oryza sativa L.) varieties in Boro season. Arch. Agr. Environ. Sci. 3(3): 245- 251. Ahmed, G.J.U., M.K.A. Bhuiyan, C.R. 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