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Bangladesh Agron. J. 2024, 26(2): 56-66 

EFFECT OF BISPYRIBAC-SODIUM AND SPACING ON THE WEED 
CONTROL AND PERFORMANCE OF AROMATIC RICE VARIETIES 

 
F.T.Z. Bushra1, T.A. Sourav2, S.C. Sarker3 and S.M. Masum3* 

 
1MS student, Department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh 

2Undergraduate Student, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesgh 
3Departement of Agronomy, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh 

*Corresponding author, Email: smmasum607@yahoo.com 
 

(Received: 11 March 2024, Accepted: 29 April 2024) 
 

Keywords: Aromatic rice, plant geometry, herbicide, weed control efficiency, weed index  
 

Abstract 
 

Rice (Oryza sativa L.), a staple grain, serves as a fundamental dietary component for billions by 
providing carbohydrates, vitamins, and minerals, supporting livelihoods, and stimulating national 
economies. A field experiment was led from July to December 2019 at the Sher-e-Bangla Agricultural 
University’s agronomy field in Dhaka, Bangladesh, to determine how a post-emergent herbicide and 
spacing impacts aromatic rice varieties' growth, yield, and weed control. The investigation consisted 
of three factors, i.e., weed control treatments: weedy check (no weeding) and Bispyribac-sodium WP 
@ 150 g ha−1, aromatic rice varieties: Kalizira and BRRI dhan37 and spacing: 20 cm × 15 cm, 25 cm 
× 15 cm, 20 cm × 20 cm, and 25 cm × 25 cm in a split-split plot design with three replications. Thirteen 
dissimilar types of weeds invaded the experimental plots. Among them, Monochoria vaginalis was 
the most prevalent weed at 30 and 60 DAT (24.67 and 19.67 weed population m−2 and  15.24 and 
13.02% relative weed density sequentially). Among all the factors, the application of Bispyribac-
sodium WP (W1), BRRI dhan47 (V2, grain yield 2.99 t ha−1) and 20 cm × 20 cm (S3, grain yield 2.87 t 
ha−1) spacing provided promising results. According to the findings, BRRI dhan37 planted at 20 cm 
× 20 cm spacing, along with the suggested application of Bispyribac-sodium WP could provide the 
best result. 
 

Introduction 
 

Bangladesh, an agrarian country with a large population, relies heavily on profound rice (Oryza 
sativa L.) cultivation. According to BBS (2022), Bangladesh’s agricultural sectors accounted for 11.66% 
of the country’s GDP in the fiscal year 2021-2022. The total area covered by aman rice was speculated 
to be 5625907 hectares, 0.87% greater than the financial year 2019-2020. In 2020, 4.44 million hectares 
of cultivable land were accustomed to HYV varieties, 0.75 million hectares for local varieties, 0.31 
million hectares for B. Aman, and 0.24 million hectares for hybrid varieties. A total of 5.71 million 
hectares of land were covered by the aman crop (Magzter, 2021). However, as per the Statistical 
Yearbook Bangladesh (BBS, 2022), Aman rice was cultivated for 34.11% of the gross area, and the 
production was 14959 MT.  

Aromatic rice, known as Basmati in India, Jasmine in Thailand, and Kataribhog in Bangladesh, 
has a 15-fold higher amount of 2-Acetyl-1-pyrroline (2AP) (Singh, 2000). Scented rice varieties in 
Bangladesh are conventional, photoperiod-sensitive and cultivated during the aman season. Despite low 
yields, these cultivars generate higher turnover due to low cultivation costs (Tanchotikul and Hsieh, 
1991). 

Weeds are undesired plants that grow in locations where they are not deliberately cultivated. 
According to Ramana et al. (2014), weeds pose the greatest drawback to agricultural productivity, with 
losses ranging from 30 to almost 100%. According to Rao et al. (2007), weeds had a devastating effect 
on crop production  caused loss of  32% across the globe. When weeds existed, the grain production of 
T. Aman, Boro, and Aus rice were lessened by 70–80, 30, and 36%, respectively, prompting increased 
use of herbicides for chemical weed control (BRRI, 2008). 



57   Bushra et al. 

Weed management in sustainable rice production is burdensome due to arduous and expensive 
physical and cultural methods. At the same time, chemical control is more inexpensive and less time-
consuming, making it more likable over time.  

The study intends to ascertain the effectiveness of a post-emergent herbicide and spacing in 
weed management and contrast the competitiveness of local and contemporary aromatic rice varieties in 
Bangladesh. 
 

Materials and Methods 
 

Site characteristics 
The study was carried out in the agronomy field of Sher-e-Bangla Agricultural University in 

Dhaka, 8.6 m above sea level and geographically located between 23°77ʹ N latitude and 90°33ʹ E 
longitude during the period from July 1 to December 20, 2019. It is situated in the Agro-Ecological Zone 
of the Madhupur Tract, AEZ-28, a complex terrain area encompassed by sediments from floodplains, 
including red soil hillocks from islands. The soil utilized in the experiment was a silty clay loam with an 
ECE of 25-28 and a pH of 5.8-6.5. Specimens of soil were taken at depths of 0 to 15 cm. The atmospheric 
condition in the region was subtropical, with high temperature, humidity, and precipitation. 
 
Experimental design and treatments 

Three variables were included in this experiment: aromatic rice varieties (V1 and V2), weed 
control treatments (W0 and W1) and spacings (S1, S2, S3, and S4). The seeds of Kalizira (V1) and BRRI 
dhan37 (V2) were procured from BRRI (Bangladesh Rice Research Institute) located in Joydebpur, 
Gazipur, after undergoing a typical selection process to ensure their health and absence of illness. 

A post-emergent herbicide called Xtra Power 20 WP (sodium 2,6-bis[(4,6-dimethoxypyrimidin-
2-yl)oxy]benzoate, W1) was used in the experiment, which was registered by ACI Crop Care and applied 
on August 23, 2019, at the rate of 150 g ha−1. It averts the synthesis of plant amino acids through being 
fastidious, systematic, and absorbed by the foliage and roots. Due to its minimal mammalian toxicity and 
great activity at modest treatment rates, this herbicide has gained popularity (De et al., 2014). The 
herbicide was administered through a knapsack sprayer, maintaining a 4-5 cm water level for 65-70 days 
following transplanting at the rate of 150 g ha−1. The other weed control treatment was W0 for which we 
applied no herbicides.  

The spacings were 20 cm × 15 cm, 25 cm × 15 cm, 20 cm × 20 cm, and 25 cm × 25 cm which 
were denoted by S1, S2, S3, and S4 consecutively. For weed treatment and variety, the investigation used 
a split-split plot design with three replications, having a unit plot size of 5.04 m2 (2.8 m × 1.8 m). 

N, P, K, S, and Zn were supplied to rice plants by urea (150 Kg ha−1), triple superphosphate  
(100 Kg ha−1), muriate of potash (70 Kg ha−1), gypsum (60 Kg ha−1) and zinc sulfate (10 Kg ha-1). The 
amounts of fertilizer used followed the criteria BRRI provided for cultivating T. Aman rice. Three split 
applications were made for urea: 21 DAT, 45 DAT as top dressing, and 60 DAT at the panicle initiation 
stage. All other fertilizers were applied in basal doses during final land preparation. 

 
Data Collection and calculations 

To better understand weed interference, the study identified specific weed species and counted 
their population in a weedy check plot of 1 m2 listed at 30 and 60 DAT. The weeds were uprooted, and 
the fresh and dry weight, relative weed density, weed control efficiency, and weed control index were 
measured by applying the following formulas: 
 

RWD (%) =
Number of individuals of same species

Number of individuals of all species
×100 

WCE (%) =
Weed population in control-weed population in treated plot 

 Weed population in control
×100 

WCI (%) =
Weed dry weight in control-weed dry weight in treated plot 

 Weed dry weight in control
×100 



Effect of bispyribac-sodium and spacing on the weed control of rice   58 

 
Grain yield was adjusted to 14% moisture, sun-dried, and weighed carefully. After measuring the dry 
weight of grains in a central 1 m2 area, the final grain yield was recorded for each plot and then converted 
to t ha−1. Grain yield was calculated using the following formula: 
 

Grain yield (t ha−1)= Grain yield per unit plot (Kg) × 10000
Area of unit plot in square meter × 1000

 
 
An arbitrary sample of 1000- cleaned dried seeds was weighed using a digital electric balance at 12% 
moisture, and the mean weight was expressed in grams. 
 

Results and Discussion 
 

In the experiment field, the names and populations of individual weed species were noted at 30 
and 60 DAT on a pre-marked area of 1 m2 of weedy check plots. Thirteen different weed species were 
heeded, with broadleaf and sedge weeds prevailing. The findings comprise 7 broad leaf weeds and 3 
grass and sedge weeds each. The result is tabulated below: 

 
Table 1. Weed flora of the experiment field 
 

 
Data on the species-specific weed population (no. m−2) and relative density (%) were recorded 

in the experiment area after 30 and 60 DAT, and Monochoria vaginalis was found to be predominant. 
Cyperus rotundus followed it, and Sagittaria guayansis was the least prominent, with Scirpus maritimus 
and Marsilea quadrifolia at 30 and 60 DAT subsequently. 
Table 2. Weed population by species (No. m−2) and relative weed density (%) in the experimental area 

at 30 and 60 DAT 
 

Scientific name 
Weed population  (No. m−2) Relative weed density (%) 
30 DAT 60 DAT 30 DAT 60 DAT 

Monochoria vaginalis 24.67 19.67 15.24 13.02 
Cyperus rotundus 20.21 18.86 12.48 12.48 
Sagittaria guayansis 19.1 17.85 11.80 11.81 
Cyperus diformis 18.08 15.34 11.17 10.15 
Ludwigia octovalvis 14.34 14.23 8.86 9.42 
Sphenoclea zeylanica 13.44 12.34 8.3 8.17 
Enydra fluctuans 12.5 11.45 7.72 7.58 

Local name English name Scientific name Family Habitat Weed type 
Shama Barnyard Grass Echinochloa cruss-galli Poaceae Annual Grass 
Choto shama Jungle rice Echinochloa colona Poaceae Perennial Grass 
Chapra Indian goosegrass Eleusine indica Poaceae Annual Grass 
Cechra Dwarf Club-rush Scirpus maritimus Cyperaceae Perennial Sedge 
Holde mutha Yellow nutsedge Cyperus diformis Cyperaceae Perennial Sedge 
Mutha Java grass Cyperus rotundus Cyperaceae Perennial Sedge 
Chondro mala Water snowflake Nymphoides cristatum Menyanthaceae Perennial Broadleaf 
Helenca Buffalo spinach Enydra fluctuans Asteraceae Annual Broadleaf 
Jheel-morich Gooseweed Sphenoclea zeylanica Sphenocleaceae Annual Broadleaf 
Pani kochu Pickerel weed Monochoria vaginalis Pontederiaceae Perennial Broadleaf 

Pani Long Mexican Primrose 
Willow Ludwigia octovalvis Onagraceae Perennial Broadleaf 

Shusni shak European water 
clover Marsilea quadrifolia Papayeraceae Perennial Broadleaf 

Chad 
mala Duckweed Sagittaria guayansis Alismataceae Perennial Broadleaf 



59   Bushra et al. 

Echinochloa colona 11.66 11.5 7.2 7.61 
Eleusine indica 8.33 7.54 5.15 4.99 
Nymphoides cristatum 7.8 9.1 4.82 6.02 
Echinochloa cruss-galli 5.34 4.35 3.3 2.87 
Marsilea quadrifolia 3.3 3.34 2.04 2.21 
Scirpus maritimus 3.1 5.54 1.92 3.67 
Total weed 161.87 151.11 100 100 

 
Presence of weeds m−2 in different weed control treatments 

Different weed-control treatments have various impacts on the number or population of weeds. 
Among the different treatments, herbicide-based weed control (W1) reduced weed m−2 at different DAT 
levels. 

 

 

 
Fig. 1. Presence of weeds m−2 ; Here, W0: Weedy, W1: Weeds control 

The population or quantity of weeds was impacted by 2 different weed control techniques at 
varying DATs. The study revealed that the weedy check plots had the highest weed density, with 13.89 
and 11.85 weeds m−2 at 30 and 60 DAT, respectively. Contrarily, the Bispyribac-sodium WP plots had 
the lowest density, with only 6.35 and 7.04 weeds m−2. 

1.
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At 60 DAT
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Effect of bispyribac-sodium and spacing on the weed control of rice   60 

 
Fig. 2. Weed Density m-2 .Here, W0: Weedy, W1: Weeds control. 

 
Presence of weeds m-2 in different rice varieties 

Rice variety treatments affected weed numbers. BRRI dhan37 (V2) was a particular rice variety 
that functions well by lessening weed m−2 at different DATs. It had the lowest weed density, as competing 
rice varieties with finer vigor are more productive in repressing weed infestation. 

 
 

 
 

Fig. 3. Varieties of rice with weed m−2 .Here, V1: Kalizira, V2: BRRI dhan37. 
 

The study was found that weed m−2  significantly influenced rice varieties at different time 
intervals (DAT). Kalizira had the highest weed densities (10.84 and 9.69 m−2), and BRRI dhan37 (V2) 
had the lowest (9.40 and 9.20 m−2). 

 
Fig. 4. Effect of variety on weed density m−2 at different DAT.Here, V1: Kalizira, V2: BRRI dhan37. 

 
Presence of weeds m−2 in different spacing: 

As per the column chart, the maximum weed density was recorded at 25 cm × 25 cm spacing, 
S4, and the lowest at 20 cm × 20 cm, S3. We can conclude that the prevalence of weeds and the 
requirement for herbicides can be lessened with the S3 spacing, as it can provide shading and lower weeds’ 
competing abilities. 

 

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At 30 DAT
V1 V2



61   Bushra et al. 

 

 
Fig. 5. Presence of weeds m−2 in different spacing. Here,  S1: 20 cm × 15 cm, S2: 25 cm × 15 cm, S3: 20 cm × 20 cm and S4: 25 cm 

× 25 cm. 
 

The experiment also revealed that varying spacing significantly impacted weed density at 
various DATs, with maximum density in 25 cm × 25 cm (S4) and minimum in 20 cm × 20 cm (S3). 

 

 
Fig. 6. Effect of spacing on weed density m−2 at different DATs. 

Weed Control Efficiency 
The weed control efficiency stretched from 19.34% to 27.88% over the weedy check plot, which 

is attributable to the different rice varieties used in the experiment. The cultivation of BRRI dhan37 (V2) 
resulted in the foremost weed control efficiency at both 30 and 60 DAT, with a percentage of 27.88% 
and 21.09%, respectively. 

 

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At 60 DAT
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11.76
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DAT

S1 S2 S3 S4 At 60
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S1 S2 S3 S4



Effect of bispyribac-sodium and spacing on the weed control of rice   62 

 
Fig. 7. Effect of variety on weed control efficiency. 

 
Aromatic rice cultivated at 20 cm × 20 cm (S3) spacing recorded the highest weed control 

efficiency (29.27% and 22.98%) at 30 and 60 DAT, which was statistically identical to the result when 
it was cultivated at 20 cm × 15 cm (S1) spacing (29.09%) at 30 DAT. 

 
Fig. 8. Effect of spacing on weed control efficiency. Here,  S1: 20 cm × 15 cm, S2: 25 cm × 15 cm, S3: 20 cm × 20 cm. and S4: 25 

cm × 25 cm. 
 
Weed Control Index  

The weed control index of aromatic rice at 30 and 60 DAT is remarkably affected by the 
varieties of rice used. It ranged from 16.32% to 30.40% over the weedy check plot. The experiment 
revealed that BRRI dhan37 (V2) recorded the maximum weed control index (30.40% and 28.81%), while 
Kalizira (V1) recorded the minimum weed control index (24.46% and 16.32%) at 30 and 60 DAT. 

 

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63   Bushra et al. 

Fig. 9. Effect of variety on weed control index. 
 

The highest weed control index was achieved when aromatic rice was cultivated at 20 cm × 20 
cm (S3) spacing with weed control indices of 30.20% and 23.92% and cultivation at a spacing of 25 cm 
× 25 cm (S4) resulted in the minimum weed control index of 21.69% and 20.24% at 30 and 60 DAT 
respectively. 

 
Fig. 10. Effect of spacings on weed control index. Here, S1: 20 cm × 15 cm, S2: 25 cm × 15 cm, S3: 20 cm × 20 cm and S4: 25 cm 

× 25 cm. 
 
Combined effects 

The study examined the collective effect of weed control and rice variety, spacing and their 
interaction effect on the weed population in the aman rice field. The study revealed that using Bispyribac-
sodium WP @ 150 g ha−1 in combination with BRRI dhan37 (W1V2) cultivation culminated in the lowest 
weed density at both time parameters. 
 
Table 3. Effects of variety and weed management combined on weed density 
 

Treatment Combinations Weeds density m−2 

DAT 30 DAT 60 
W0V1 14.75 ± 1.32a 12.00 ± 1.08a 
W0V2 13.02 ± 1.62b 11.69 ± 0.72b 
W1V1 6.93 ± 1.31c 7.38 ± 1.15c 
W1V2 5.77 ± 0.93d 6.71 ± 0.48d 
SE± 0.04 0.14 
CV (%) 1.94 2.28 

The weed density was even lower when the herbicide was used with narrow spacing (20 cm × 
20 cm). Ultimately, the soundest method for curtailing weed density was using the herbicide with BRRI 
dhan37 cultivation and narrow spacing (20 cm × 20 cm). 
 
Table 4. Effects of weed control, variety, and spacing combined on weed density 
 

Treatment Combinations Weeds density m−2 

DAT 30 DAT 60 
W0V1S1 13.00 ± 0.68d 11.67 ± 0.52b 
W0V1S2 15.00 ± 0.79c 12.00 ± 0.63b 
W0V1S3 15.00 ± 0.78c 11.67 ± 0.61b 
W0V1S4 16.00 ± 0.84a 12.67 ± 0.65a 
W0V2S1 11.34 ± 0.59f 9.98 ± 0.61c 
W0V2S2 12.44 ± 0.65e 11.67 ± 0.61b 
W0V2S3 13.00 ± 0.68d 12.67 ± 0.67a 
W0V2S4 15.30 ± 0.81b 12.44  ± 0.65a 

28.07
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29.77

22.29

30.2
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DAT 30 DAT 60

W
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S1 S2 S3 S4



Effect of bispyribac-sodium and spacing on the weed control of rice   64 

W1V1S1 5.37 ± 0.28k 6.67 ± 0.33fg 
W1V1S2 7.13 ± 0.38h 7.00  ± 0.37ef 
W1V1S3 6.47 ± 0.34i 6.77  ± 0.37f 
W1V1S4 8.74  ± 0.46g 9.06  ± 0.48d 
W1V2S1 5.17  ± 0.27k 6.34 ± 0.33g 
W1V2S2 6.10  ± 0.32j 7.33  ± 0.39e 
W1V2S3 4.80  ± 0.25l 6.33  ± 0.33g 
W1V2S4 7.01 ± 0.37h 6.84  ± 0.36f 
SE± 0.08 0.28 
CV (%) 1.39 2.43 

Note viz: NS=Non- significant; W0:Weedy check and W1: Bispyribac-sodium WP @ 150 g ha-1; V1: Kalizira and V2: BRRI dhan37; 
S1: 20 cm × 15 cm, S2: 25 cm × 15 cm, S3: 20 cm × 20 cm and S4: 25 cm × 25 cm 
 

Bispyribac sodium WP @ 150 g ha−1 herbicide-treated plot along with BRRI dhan37 cultivation 
at 20 cm × 20 cm spacing recorded the maximum weed control efficiency (60.23% and 49.96%) at 30 
and 60 DAT respectively. 
 
Table 5. The combined effect of weed control, variety, and spacings on weed control efficiency and weed 

control index of aromatic rice at different DAT 
Treatment 
Combinations 

Weed control efficiency Weed control index 

DAT 30 DAT 60 DAT 30 DAT 60 
W0V1S1 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V1S2 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V1S3 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V1S4 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V2S1 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V2S2 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V2S3 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W0V2S4 0.00 ± 0h 0.00 ± 0f 0.00 ± 0h 0.00 ± 0h 
W1V1S1 58.69± 1.17b 42.85± 0.73c 47.64± 0.95f 36.49 ± 0.46e 
W1V1S2 52.47 ± 1.05e 41.67 ± 0.83c 55.63 ± 1.11d 32.62 ± 0.65f 
W1V1S3 56.87± 1.14c 41.98 ± 0.84c 54.98 ± 1.1d 30.96 ±0.62fg 
W1V1S4 45.38 ± 0.91g 28.27 ± 0.53e 37.46 ± 0.75g 30.51 ±0.61g 
W1V2S1 57.67 ± 1.15c 36.57 ± 0.86d 64.65 ± 1.29b 58.78 ±0.97b 
W1V2S2 50.95 ± 1.02f 37.19 ± 0.74d 63.46± 1.27c 56.55 ±1.13c 
W1V2S3 60.23 ± 1.2a 49.96 ± 0.99a 65.80 ± 1.32a 64.73± 1.15a 
W1V2S4 54.15 ± 1.24d 45.00 ± 0.89b 49.30 ± 0.99e 50.44± 1.1a 
SE± 0.71 0.87 1.09 1.17 
CV (%) 1.94 6.11 2.04 4.63 

A column means having a similar letter(s) are statistically similar and those having a dissimilar letter(s) differ significantly at 0.05 
probability level. Note viz: NS=Non- significant; W0:Weedy check and W1: Bispyribac-sodium WP @ 150 g ha-1; V1: Kalizira and 
V2: BRRI dhan37; S1: 20 cm × 15 cm, S2: 25 cm × 15 cm, S3: 20 cm × 20 cm and S4: 25 cm × 25 cm 
Grain yield and 1000‐grain weight 

Rice varieties have a significant impact on grain yield, with the BRRI dhan37 (V2) rice variety 
achieving a maximum yield (2.99 t ha−1) due to its higher filled grains per panicle and 1000 grain weight 
(17.56 g). 



65   Bushra et al. 

Fig. 11. Effect of variety on grain yield and 1000‐grain weight. Here, V1: Kalizira and V2: BRRI dhan37. 
 

The study also found that spacing significantly affects the grain yield of aromatic rice. The 
maximum yield and 1000‐grain weight were recorded at the spacing of 20 cm × 20 cm (S3, 2.87 t ha−1 
and 16.68 g respectively), followed by 25 cm × 15 cm, and lowest in 25 cm × 25 cm (S4) in both 
parameters. 

 
Fig. 12. Effect of spacing on grain yield and 1000−grain yield. Here, S1: 20 cm × 15 cm, S2: 25 cm × 15 cm, S3: 20 cm × 20 cm, S4: 

25 cm × 25 cm 
 

Conclusion 
 

The study was led to investigate the consequences of a post-emergent herbicide and spacing on 
the weed control and growth of two aromatic rice varieties that are extensively cultivated in Bangladesh. 
Among  different treatments, Bispyribac-sodium WP @ 150 g ha−1 herbicide-treated plots (W1) were 
reported as having the minimum weed density m−2 (6.35 and 7.04 m-2) at 30 and 60 DAT. Rice varieties 
notably affected weeds, and BRRI dhan37 (V2) was perceived as having the minimum weed density m−2 
(9.40 and 9.20 m−2) at 30 and 60 DAT. In terms of spacing, 20 cm × 20 cm (S3) was proven to be 
outstanding. To conclude, it was recorded that cultivation of BRRI dhan37 along with Bispyribac-sodium 
WP @ 150 g ha−1 and a spacing of 20cm × 20cm influenced the outcome appreciatively. However, further 
trials with the same treatment combination in separate locations in Bangladesh would be more useful 
before delivering a closing statement. 
 

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