Assessment of post-emergence weed management in direct-seeded rice

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Assessment of post-emergence weed management in direct-seeded rice
V. Pratap Singh*, S.P. Singh, Neema Bisht, A. Kumar, Kavita Satyawali and Arunima Paliwal
Department of Agronomy, College of Agriculture, Govind Ballabh Pant University of Agriculture &
Technology Pantnagar, U.S. Nagar, Uttarakhand 263 145
Received: 4 July 2017; Revised: 19 August 2017
ABSTRACT
The present study was carried out at G.B. Pant University of Agriculture and Technology, Pantnagar
during rainy seasons 2014 and 2015 to determine the efficacy of post-emergence application of
cyhalofop-butyl in managing weeds in direct-seeded rice. Eight treatments, viz. cyhalofop-butyl 10% EC
at 65, 75, 80 and 90 g/ha, cyhalofop-butyl 10% EC at 75 and 80 g/ha, hand weeding twice at 20 and 40 DAS
and untreated control were laid out in a randomized block design with three replications. Application of
cyhalofop-butyl controlled grassy weeds better than the non-grassy weeds and recorded maximum
weed control efficiency, higher yield attributes and yield. Application of cyhalofop-butyl in rice did not
show any phytotoxic effect on succeeding wheat.
Key words: Cyhalofop-butyl, Herbicide, Herbicide efficiency index, Weed control efficiency, Yield
Rice (Oryza sativa) is a major cereal crop and
staple food for more than half of the world’s
population. About 90% of the world’s rice is
produced and consumed in Asia (FAO 2014). The
world’s total rice area is 168 Mha and production is
about 722 M tons with the productivity of 4.29 t/ha
(FAOSTAT 2012). Puddling for transplanted rice
cause to dispersion of soil particles and consequent
compaction of the soil and is labour intensive
(Chauhanet al. 2012). The direct-seeded rice (DSR)
cultivation, which does not need puddling and
transplanting was found as feasible alternative to save
water and labour (Ghosh et al. 2016). DSR is a cost
effective rice establishment method where dry seed is
drilled into the non-puddled soil. This provides
opportunities of saving irrigation water by 12-35%,
labor up to 60% and provides higher net returns (US$
30-50/ha) with similar or slightly lower yield of rice
(Kumar and Ladha 2011). Despite multiple benefits of
dry DSR, weed control remains one of the major
challenges for its success in South Asia (Kumar and
Ladha 2011, Rao et al. 2007, Singh et al. 2008).
Since the concept of aerobic rice is new (Belder et al.
2005) growing rice under aerobic conditions on
raised beds or flat land would require suitable,
effective and economic weed-control methods. Both
pre-emergence and post-emergence herbicides can
be used in aerobic rice fields and they are effective, if
properly used (De Datta and Baltazar 1996, Singh et
al. 2006). In spite of use of different chemicals as
pre-emergence and post-emergence, certain weeds
like Leptochloa chinensis and other grassy weeds are
still not controlled. Hence, the present study was
undertaken to determine the efficacy of cyhalofop-
butyl as post-emergence application against grassy
weeds in direct-seeded rice.
MATERIALS AND METHODS
The field experiment was conducted at
GBPUA&T, Pantagar (290N latitude, 27.30E longitude
and at an altitude of 243.8 m above the mean sea
level) during the rainy season of 2014 and 2015. The
climate of Pantnagar is very hot in summers and cold
in winters. The hottest months are May and June,
when the maximum temperature reaches 400C,
whereas during December and January, the coldest
month of the year, the minimum temperature often
remains below 100C and may reach to 10C. The
average rainfall is 1450 mm, 80% of which is
received through the monsoon from June to
September.
The experiment was laid out in a randomized
block design with three replications. Eight treatment
combinations were made up with different
herbicides, hand weeding and weedy check as
follows: Cyhalofop-butyl 10% EC at 65 g/ha,
cyhalofop-butyl 10% EC at 75 g/ha, cyhalofop-butyl
10% EC at 80 g/ha, cyhalofop-butyl 10% EC at 90 g/
ha, cyhalofop-butyl 10% EC (standard check) at 75
g/ha, cyhalofop-butyl 10% EC (std. check) at 80 g/
ha, two hand weeding (20 and 40 days after sowing;
*Corresponding author: vpratapsingh@rediffmail.com
Indian Journal of Weed Science 49(3): 211–215, 2017
DOI: 10.5958/0974-8164.2017.00056.9

212
DAS) and weedy check. Herbicides were applied
using a power operated knapsack sprayer fitted with
a flat fan nozzle and water as a carrier at 500 liter/ha.
In the weedy check, no weeding was done. For
phytotoxicity study, cyhalofop-butyl 10% EC (std.
check) was applied at 160 g/ha in direct-seeded rice.
Rice (‘Sarjoo 52’) was seeded manually in line on 13th
June, 2014 and 11th June, 2015 using seed rate of 50
kg/ha. Row to row spacing was 20 cm with
continuous rice plants in a row. Thinning was done
manually at 15 DAS to maintain plant population.
Irrigation was applied in the field as per requirement.
The soil was loamy, medium in organic matter
(0.67%), available nitrogen (210 kg/ha), phosphorus
(17.5 kg/ha) and potassium (181.2 kg/ha) with pH
7.5. Half of nitrogen, full dose of phosphorous and
potash were applied as basal and remaining half of
nitrogen was applied in two split doses first at active
tillering and second at panicle initiation stage in all
treatments. Observations were taken on density and
biomass of weeds, weed control efficiency (WCE),
herbicide efficiency index (HEI) and weed
persistence index at 45 DAS by placing a quadrate of
0.25 m2 at four randomly selected places. Removed
weed flora was oven dried at 700C for 72 hours. Crop
was harvested on October 27, 2014 and October 25,
2015 and left in the field for 5-7 days for sun drying.
The number of panicles/m2, grains/panicle, 1000
grain weight, grain yield, straw yield and grain straw
ratio was recorded. Data were analyzed by using
standard statistical techniques (STPR package).
Phytotoxic symptoms were recorded in direct-seeded
rice on 3, 7, 14, 21 and 28 days after herbicide
application at a dose of 80 and 160 g/ha of cyhalofop-
butyl by comparing it with weedy check. Carry over
effect of applied herbicides also observed on
succeeding wheat crop.
RESULTS AND DISCUSSION
Relative weed density
At 45 days after herbicide application (DAA) the
experimental area of direct-seeded rice crop was
infested with different grassy and non-grassy weeds
during both the years of experimentation. Among
grassy weeds Echinochloa colona, E. crus-galli and
Leptochloa chinensis were dominant and among non-
grassy weeds Alternanthera sesillis, Caesulia
axillaris, Cyperus iria and Cyperus rotundus were
major weeds. Echinochloa colona, E. crus-galli, L.
chinensis and non-grassy weeds accounted 7.7, 7.7,
9.5 and 75.1% during 2014 and 4.1, 7.6, 4.7 and
83.6% relative weed density during 2015,
respectively in weedy check plot (Table 1).
Density and dry biomass of weeds
During 2014, the minimum density and biomass
of E. colona and E. crus-galli was recorded with the
application of cyhalofop-butyl at 90 g/ha, which was
comparable with its lower dose applied at 80 (both
sponsor sample and std. check) and 75 g/ha while
during 2015, all the herbicidal treatments except
cyhalofop-butyl at 65 g/ha completely eliminated E.
colona whereas the density as well as dry biomass of
E. crus-galli was found minimum with the
application of cyhalofop-butyl at 90 g/ha, which was
at par with its lower dose applied at 75 and 80 g/ha.
All the doses of cyhalofop-butyl except its lower dose
at 65 g/ha recorded complete elimination of L.
chinensis during both the years of experimentation
while during 2015, std. check of cyhalofop-butyl at
75 g/ha also not achieved complete control over its
density and dry biomass. None of the herbicidal
treatments was found effective in controlling the
density and dry biomass of non-grassy weeds over
the weedy check treatment. Minimum density of
grassy weeds is due to selectivity of herbicide. This
herbicide was more effective against the grassy
weeds as compared to broad leaf weeds and sedges
and lowest dry biomass of grassy weeds might be
due to low density of grasses as compared to non-
grassy weeds.
Total weed dry biomass, WCE, HEI and WPI
Minimum total dry biomass of weeds was
recorded with the post-emergence application of
cyhalofop-butyl at 90 g/ha which was significantly
superior to rest of the treatments except twice hand
weeding at 20 and 40 DAS during 2014 while during
2015, cyhalofop-butyl applied at 90 g/ha as post-
emergence was comparable with rest of the weed
management practices except with the application of
cyhalofop-butyl at 65 g/ha. Among different
herbicidal treatments, application of cyhalofop-butyl
at 90 g/ha as post-emergence recorded maximum
weed control efficiency (WCE) of 70.2 and 74.0%
during 2014 and 2015, respectively (Table 3).
Maximum herbicide efficiency index (HEI) was
attained (21.7 and 13.9%) with the application of
cyhalofop at 90 g/ha during 2014 and 2015,
respectively, which was followed by its lower dose
applied at 80 g/ha. During 2014, application of
cyhalofop-butyl at 90 g/ha obtained minimum weed
persistence index (WPI) (0.42%) that was followed
by cyhalofop-butyl (std. check) at 80 g/ha, whereas,
during 2015, cyhalofop-butyl (std. check) at 75 g/ha
recorded lowest weed persistence index (0.32%),
which was followed by cyhalofop-butyl at 90 g/ha
Assessment of post-emergence weed management in direct-seeded rice

213
(Figure 1).Thus, with the increase in herbicide
efficiency index, weed persistence index is
decreases. As compared to 2015, in 2014 greater
herbicide efficiency index as well as weed persistence
index was recorded.
Yield attributes
All yield attributing characters of rice crop, viz.
number of panicles/m2, grains/panicle and 1000 grain
weight were significantly influenced by different
weed control treatments during both the years of
Table 1. Effect of treatment on weed density (no./m2) at 45 days after herbicide application
Treatment
Grasses Non grassy weeds
E. colona E. crus-galli L. chinensis
2014 2015 2014 2015 2014 2015 2014 2015
Cyhalofop-butyl (65 g/ha) 3.2(9.3) 1.7(2.0)
3.0(8.0)
2.4(4.7)
2.5(5.3)
4.7(2.4) 14.5(210.7)
13.4(179.3)
Cyhalofop-butyl (75 g/ha) 2.1(3.3) 1.0(0.0)
2.0(3.0)
1.5(1.3)
1.0(0.0)
1.0(0.0) 13.3(178.7)
13.2(174.7)
Cyhalofop-butyl (80 g/ha) 1.9(2.7) 1.0(0.0)
1.9(2.7)
1.2(0.7)
1.0(0.0)
1.0(0.0) 12.2(150.7)
13.0(168.7)
Cyhalofop-butyl (90 g/ha) 1.5(1.3) 1.0(0.0)
1.5(1.3)
1.0(0.0)
1.0(0.0)
1.0(0.0) 12.6(158.0)
13.4(178.7)
Cyhalofop-butyl (std. check) (75 g/ha) 2.5(5.3) 1.0(0.0)
2.5(5.3)
2.2(4.0)
1.0(0.0)
1.9(2.7) 12.0(142.7)
13.9(191.0)
Cyhalofop-butyl (std. check) (80 g/ha) 1.9(2.7) 1.0(0.0)
1.9(2.7)
1.9(2.7)
1.0(0.0)
1.0(0.0) 12.8(162.7)
13.2(174.7)
Hand weeding 20 and 40 DAS 2.5(5.3) 1.5(1.3)
2.2(4.0)
1.9(2.7)
3.2(9.3)
1.5(1.3) 7.9(62.7) 10.4(108.0)
Weedy check 4.3(17.3)
3.2(9.3)
4.3(17.3)
4.3(17.3)
4.7(21.3)
3.4(10.7)
13.0(168.7)
13.8(190.7)
LSD (p=0.05) 0.60 0.3 0.50 0.6 0.31 0.40 2.1 1.24
Value in parentheses was original and transformed to square root for analysis, DAS- Days after sowing
Table 2. Effect of treatment on weed dry biomass (g/m2) at 45 days after herbicide application
Treatment
Grasses Non grassy weeds
E. colona
E. c
rus
-
galli
L. chinensis
2014 2015 2014 2015 2014 2015 2014 2015
Cyhalofop-butyl (65 g/ha) 5.2(26.7) 2.6(5.8) 5.0(24.0) 3.1(8.5) 3.5(11.4) 2.1(3.4) 8.6(73.0)
8.1(65.2)
Cyhalofop-butyl (75 g/ha) 3.1(8.7) 1.0(0.0) 2.8(7.3) 1.7(2.0) 1.0(0.0) 1.0(0.0) 7.9(61.9)
8.0(63.5)
Cyhalofop-butyl (80 g/ha) 3.0(8.3) 1.0(0.0) 2.8(7.0) 1.3(0.8) 1.0(0.0) 1.0(0.0) 7.8(60.4)
7.8(60.1)
Cyhalofop-butyl (90 g/ha) 2.1(3.9) 1.0(0.0) 2.0(3.7) 1.0(0.0) 1.0(0.0) 1.0(0.0) 7.6(57.3)
7.7(59.0)
Cyhalofop-butyl (std. check) (75 g/ha)
4.1(16.2) 1.0(0.0) 4.0(14.9) 2.0(3.2) 1.0(0.0) 1.8(2.1) 7.5(55.5)
7.7(58.1)
Cyhalofop-butyl (std. check) (80 g/ha)
3.1(8.8) 1.0(0.0) 2.82(7.7) 1.9(2.7) 1.0(0.0) 1.0(0.0) 7.8(59.9)
7.6(57.7)
Hand weeding 20 and 40 DAS 4.2(16.6) 2.6(6.9) 3.6(12.3) 1.9(2.8) 4.2(16.4) 1.7(2.1) 4.8(22.3)
5.2(26.6)
Weedy check 7.8(60.3) 8.3(67.6) 7.1(49.2) 9.8(95.3)
6.7(44.5) 3.4(10.9) 8.0(63.5)
7.3(53.1)
LSD (p=0.05) 1.0 0.9 0.82 0.70 0.27 0.43 0.83 0.85
Value in parentheses was original and transformed to square root for analysis, DAS- Days after sowing
Table 3. Effect of treatments on total weed dry biomass
and WCE at 45 DAA
Treatment
Total weed dry
biomass(g/m2)
Weed
control
efficiency
(%)
2014 2015 2014 2015
Cyhalofop
-
butyl (65 g/ha)
11.7(135
)
9.1(83
)
37.9
63.5
Cyhalofop
-
butyl (75 g/ha)
9.4(87
)
8.1(65
)
60.0
71.1
Cyhalofop-butyl (80 g/ha) 8.8(77) 7.9(61) 64.7 73.2
Cyhalofop
-
butyl (90 g/ha)
8.1(65
)
7.7(59
)
70.2
74.0
Cyhalofop-butyl (std. check)
(75 g/ha) 9.4(87) 8.0(63.4)
60.2 72.1
Cyhalofop
-
butyl (std. check)
(80 g/ha)
8.8(76
)
7.8(60
)
64.8
73.4
Hand weeding 20 and 40 DAS
8.3(67
)
6.3(38
)
68.9
83.1
Weedy check 14.8(218)
15.1(227)
- -
LSD (p=0.05) 0.40 0.77 - -
Value in parentheses was original and transformed to square
root for analysis, DAS- days after sowing, DAA- days
after herbicide application and WCE- weed control efficiency.
study except 1000-grain weight during 2014 (Table
4). Yield attributes data depicted highest value under
twice hand weeding at 20 and 40 DAS during both the
years. Within herbicidal treatments, application of
cyhalofop-butyl at 90 g/ha achieved maximum
panicles number of 232 and 253/m2 during 2014 and
2015, respectively, which was at par with rest of the
herbicidal treatments except cyhalofop-butyl applied
at 65 g/ha. During 2014, cyhalofop-butyl applied at
90 g/ha and during 2015 application of cyhalofop-
butyl at 80 g/ha obtained highest number of grains/
panicle, which was comparable to rest of the
treatments. 1000-grain weight was maximum (24.5
g) with the application of cyhalofop-butyl at 80 g/ha
which was significantly superior to cyhalofop-butyl
applied at 65 g/ha. This might be due to less density
and biomass of weeds, less crop weed competition
during critical period, better environment for rice
V. Pratap Singh, S.P. Singh, Neema Bisht, A. Kumar, Kavita Satyawali and Arunima Paliwal

214
growth at higher doses of cyhalofop-butyl, which in
turn resulted in highest value for yield attributes of
rice crop.
Grain and straw yield
The highest grain yield (4.21 and 4.29 t/ha) was
found with the application of cyhalofop-butyl at 90 g/
ha which was comparable with rest of the herbicidal
treatments except with its lower dose applied at 65 g/
ha (Table 4). The grassy weeds dominant at critical
period of weed competition stage (Table 1 and 2)
were well managed by cyhalofop-butyl. Menono et
al. (2014) also reported that maximum rice yield with
application of cyhalofop-butyl either applied as alone
or in combination. The highest straw yield was
recorded with the application of cyhalofop-butyl at 80
Table 4. Rice yield and yield attributing characters of direct-seeded rice as affected by treatments
Table 5. Effect of various doses of cyhalofop-butyl applied in rice on the succeeding wheat crop, Rabi season
Treatment
Panicles
(no./m2) Grains/
panicle 1000 grain
weight (g) Grain yield
(t/ha) Straw yield
(t/ha) Grain: Straw
2014
2015
2014
2015 2014
2015 2014
2015
2014 2015
2014
2015
Cyhalofop-butyl(65 g/ha) 134
223 92.7
94.5 23.9 23.0 2.97
3.50
4.31 6.30 0.69
0.55
Cyhalofop-butyl (75 g/ha) 225
251 97.7
104.5 24.2 24.3 4.07
4.10
7.36 7.38 0.55
0.56
Cyhalofop-butyl (80 g/ha) 229
252 98.0
106.7 24.2 24.5 4.17
4.16
7.46 7.48 0.56
0.56
Cyhalofop-butyl (90 g/ha) 232
253 99.3
104.5 24.3 24.1 4.21
4.29
7.29 7.73 0.58
0.56
Cyhalofop-butyl (std. check)(75g/ha)
225
238 97.7
103.5 24.1 23.9 4.00
4.02
7.19 7.24 0.57
0.55
Cyhalofop-butyl (std. check)(80g/ha)
227
247 98.7
105.1 24.3 24.4 4.12
4.07
5.99 7.44
0.69
0.55
Hand weeding 20 and 40 DAS 246
265 109.3
111.3 24.1 24.7 4.25
4.34
6.67 7.81 0.64
0.56
Weedy check 112
138 54.0
67.0 23.6 22.2 0.65
1.19
1.17 2.13 0.56
0.56
LSD (p=0.05) 30.5
27.3 6.6 14.2 NS 1.36 0.38
0.29
0.48 0.50 - -
DAS- days after sowing
Treatment
Plant
population
(m2)
Spikes
(no/m2) Grains/spike
1000 grain
weight (g) Grain yield
(t/ha) Straw yield
(t/ha)
2014-
15 2015-
16 2014-
15 2015-
16 2014-
15 2015-
16 2014-
15 2015-
16 2014-
15 2015-
16 2014-
15 2015-
16
Cyhalofop
-
butyl(65 g
/ha)
262
229
296
329
42.6
41.3
44.4
39.4
4.39
4.02
6.41
6.90
Cyhalofop
-
butyl (75 g/ha)
256
224
285
307
43.1
40.5
44.4
40.2
4.30
4.20
6.47
7.14
Cyhalofop-butyl (80 g/ha) 256 225 273 309 43.0 41.5 44.2 39.0 4.46 4.20 6.36 7.15
Cyhalofop-butyl (90 g/ha) 234 230 292 275 41.6 40.5 43.5 40.3 4.14 4.01 6.52 6.81
Cyhalofop-
butyl (std.
check)(75g/ha) 245 223 304 304 42.7 41.0 45.1 39.1 4.52 4.14 6.46 6.98
Cyhalofop-
butyl (std.
check)(80g/ha) 241 225 288 298 42.4 40.4 45.7 39.5 4.10 4.10 7.05 6.97
Hand weeding 20 and 40 DAS 267 222 286 284 42.7 40.7 45.0 39.5 4.18 3.95 6.63 6.72
Weedy check 269 224 280 328 42.1 41.4 45.4 39.5 4.30 4.02 6.74 6.80
LSD (p=0.05) NS NS NS NS NS NS NS NS NS NS NS NS
DAS- days after sowing, NS- non significant
Assessment of post-emergence weed management in direct-seeded rice

215
g/ha in 2014 and 90 g/ha during 2015, which were
significantly superior to cyhalofop-butyl applied at 65
g/ha. The highest grain yield of rice was obtained
with cyhalofop-butyl at 90 g/ha due to better control
of grassy weeds. Maximum grain: straw ratio was
recorded with cyhalofop-butyl at 65 g/ha and
cyhalofop-butyl (std. check) at 80 g/ha (0.69) during
2014 and with application of cyhalofop-butyl at 75,
80 and 90 g/ha as well as twice hand weeding at 20
and 40 (0.56) during 2015.
Phytotoxicity
No phytotoxic symptoms were seen in direct-
seeded rice crop due to application of cyhalofop-butyl
at different doses on 3, 7, 14, 21 and 28 days after
herbicide application during both the years.
Carryover effect
In succeeding wheat crop, the plant population
at harvest as well as wheat yield and yield attributing
characters were not influenced significantly due to
various weed control treatments applied during
preceding rice crop and they were statistically similar
to each other. This concludes that post emergence
application of cyhalofop-butyl against weeds in
direct-seeded rice crop during rainy season was very
safe for growing wheat crop during winter season
(Table 5).
It was concluded that cyhalofop-butyl should be
applied at 75 and 80 g/ha for better control of grassy
weeds and maximum rice grain yield. The succeeding
wheat crop had no phytotoxic effect due to
application of cyhalofop-butyl.
ACKNOWLEDGEMENT
The authors gratefully acknowledge Crystal
Crop Protection Pvt. Ltd. for financial assistance.
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V. Pratap Singh, S.P. Singh, Neema Bisht, A. Kumar, Kavita Satyawali and Arunima Paliwal