Different weed management practices for direct-seeded rice systems
Stale seed bed
High seedling rate
Row seedling in
Crop residue as
USE CLEAN CROP SEED
MACHINERY USED FOR TILLAGE
SOWING HARVESTING OPRETION
SHOULD ALSO BE CLEAND
BUND AND IRRIGATION CANAL FREE
APPROCHES IN DSR
Stale seedbed technique
Row spacing and seed rate
Crop residue as mulches
Stale seedbed practice
In this practice, weed seedlings are allowed to
emerge after light irrigation and then killed
by nonselective herbicide application or tillage
EFFECT OF TILLAGE SYSTEM ON SEEDLING EMERGENGE OF
DIFFERENT WEED SPECIES UNDER AEROBIC RICE SYSTEM
EFFECT OF HIGH SEED RATES
In many countries, high seeding rates are used in direct-seeded
High seeding rates result in rapid canopy closure.and reduce
High seeding rates may help to suppress weed growth and
reduce grain yield losses due to weeds.
In such conditions, farmers cannot use high seeding rates
because of the high cost incurred for seeds. Because of the
availability of suitable sowing drills or planters with precise
seed-metering devices , seeding rates of only 15 to 25 kg ha−1
are used for sowing dry-seeded rice crops.
IN ROW-SEEDED CROPS,WEED EMERGING BETWEEN THE ROWS CAN BE
DISTINGUISHED AND PULLED OUT.
DIRECT-SEEDED CROP SHOULD BE GROWN USING NARROW ROW SPACING TO
OBTAIN FASTER CANOPY CLOSURE AND LESS PENETRATION
OF LIGHT AND ULTIMATELY LESS WEED GROWTH.
IN WEED-FREE ENVIRONMENTS, THE GRAIN YIELD
MAY BE SIMILAR BETWEEN A CROP PLANTED WITH
20-CM OR 30-CM ROW SPACING.
SEED-SOWING DRILLS ARE CAPABLE OF SEEDING AT 18- TO 20-CM ROW
EFFECT OF ROW SEEDLING IN NARROW SPACING
CROP RESIDUES OF PREVIOUS CROPS IF LEFT ON
SOIL SURFACE AS MULCH CAN SUPPRESS WEEDS IN
DSR THROUGH MULTIPLE MECHANISMS,
INCLUDING, CREATING A PHYSICAL HINDRANCE
TO EMERGING WEEDS OR BY RELEASING
ALLELOCHEMICALS IN THE SOIL.
Crop residue as mulches
The use of residue as mulches can help in suppressing weed emergence and weed
growth in dry-seeded rice systems
EFFECT OF ESTABLISHMENT METHOD ON WEED MANAGEMENT
Effect of sowing methods in DSR
Weed dry matter
Pudding- direct broadcast 2.71 (9.8) 258 41.4
ZT- direct line 3.23 (14.8) 173 35.9
ZT- direct broadcasting 3.42 (16.8) 190 38.2
Transplanting 1.0 (0) 240 54.9
Late transplanting 1.09 (1.2) 260 49.3
CD (p=0.05) 0.28 37 8.9
Walia et al (2006)Lomy sand, PR 115
Effect of crop establishment methods in DSR
LAI at 60
Dry seeding 80.8 2.89 32.3 38.41 0.48
Drum seeding 82.1 3.27 19.4 50.62 1.19
Zero tillage 83.0 2.98 38.9 42.27 0.80
Transplanted 83.3 3.46 15.3 55.29 0.96
CD (p=0.05) 0.9 0.17 7.1 4.12 -
Yadav and Singh (2006)Sity loam
EFFECT OF FLOODING
Flooding is considered the best weed
management option in rice.
Flooding can suppress the emergence and
growth of several weed species
Early and continuous flooding at a shallow
depth (e.g., 2 cm) can also help to suppress the
emergence and growth of problematic weeds
Effect of Genotypes
Competitive cultivar can suppress weed seed production, limit future
weed infestation, and become a safe, environmentally benign and low cost
tool for weed management
early fast growth, maximum number of leaf, tall stature of plant
and more tillering capacity have better competitive ability against
weed than slow growing cultivars
The choice of a cultivar plays an important role in crop-weed
competition due to the cultivar’s morphological characters and the
competitive ability of rice is usually associated with light
Roy and Mishra (1999)Sandy loam
Dry weight of
41.2 68.0 281.4 19.5 21.5
ES 18-11-2 62.8 63.0 264.7 18.5 19.2
CD (p=0.05) 4.0 3.2 6.8 0.5 1.2
Performance of rice genotypes under DSR
Using hand pused weeeder (e.g., cono weeder)
Note;- the use of mechanical weeder is feasiable
only where rice planted in row
DRY-SEEDED RICE ROW SEEDING WITH INTERROW WEEDING
USING HOES AND WITHOUT ANY HERBICIDE ACHIEVED HIGHER
GRAIN YIELD (SATOSHI ET AL., 2009).
OPINED THAT RICE FARMERS CAN USE ROTARY WEEDING INSTEAD
OF HERBICIDE IN CONTROLLING WEEDS AND ACHIEVE THE SAME
GRAIN YIELD OF WET-SEEDED RICE. (MNGUU 2010)
Pre -plant herbicides
Preplant herbicides: These are used to knock down existing weeds of a
nature before planting.
Use glyphosate @ 1.0 kg a.i./ ha in 400–500 L of water. It is preferable that the
control of perennial weeds and seeding of rice should be done 7–10 days after
Use flat fan nozzles for spraying.
Best results are obtained when weeds are in active growth stages. If weeds are
vegetating (not growing).
Apply light irrigation several days before glyphosate spray. This knocks down
all weeds, including Cynadon dactylon and Cyperus rotundus.
Use paraquat @ 0.5 kg a.i. /ha in 600 L of water (preferably should be used
when perennial weeds are not present, and sowing can be done immediately
Pre-emergence herbicides are generally used before the emergence of weeds.
Thus,these chemical molecules are applied immediately after the sowing of the crops.
Use pendimethalin @ 1.0 kg a.i./ ha in 600–750 L of water/ha in moist
conditions and in evening hours.
Pretilachlor with safener at 0.50 kg a.i./ ha in standing-water conditions.
Postemergence herbicides are used to knock down weeds after they are up or
Use Almix at 0.004 kg a.i. ha for the control of broadleaf weeds and annual
sedges. It also suppresses Cyperus rotundus for a fewdays.
Use 2,4-D at 0.5–0.75 kg a.i./ ha for knocking down Sesbania, annual sedges
and broad leaf weeds.
Use Azimsulfuron @ 0.030 kg a.i./ ha to control most weeds, including
Cyperus species, except grasses.
Effect of stale bed method, on weed management
TREATMENT Weed density
Dry seeded after stale bed
using shallow tillage
Dry seeded after stale bed
using glyphosate1kg/ ha
LSD(P=0.05 0.82 NS
Effect of seed rate and weed control in WSR
Seed rate (kg/ha)
40 9.23 52.63 389.9 44.7
50 9.22 52.74 394.8 45.8
60 9.21 52.85 401.3 46.2
CD (p=0.05) NS - NS NS
Weed control treatments
Pretila 0.75 7.67 61.59 410.4 50.6
Pendi 0.75 7.63 61.93 417.6 53.6
2 HW 7.56 65.52 420.3 54.2
Unweeded 15.47 - 306.1 15.4
CD (p=0.05) 0.17 - 29.2 4.54
Payman and Singh (2008)Loamy sand, Wet seeding, SPD
Effect of different weed control treatments on weeds and DSR
Weed dry wt.
Pretilachlor 0.37 + Safener 3.8 (14.0)* 15.2 (13.3) 57.3
Pretilachlor 0.56 + Safener 3.6 (12.0) 14.8 (1.2) 57.7
Pretila 0.37 + Safe + 1 HW 2.4 (5.0) 12.4 (5.3) 59.7
Pretilachlor 0.62 4.5 (20.0) 17.5 (20.7) 55.4
Pretilachlor 0.94 3.9 (14.0) 16.1 (15.8) 57.2
Pretila 0.62 + 1 HW 3.0 (8.0) 13.5 (8.2) 59.0
2 HW (20 and 45 DAS) 8.7(74.3) 24.5 (50.0) 58.3
Weedy 9.6 (92.3) 33.0 (99.7) 40.8
CD (p=0.05) 0.8 (6.8) 1.8 (10.3) 0.5
Mahajan et al (2003)*Figures in parenthesis are original values
Sq. root transformation is used
Effect of seeding methods, intercropping and weed
management in DSR
Panicles/m2 Grain yield
Surface 1.85 (90.4) 365 46 1.77
Anaerobic 1.83 (87.1) 373 47 1.84
CD (p=0.05) NS NS NS
Sole rice 2.07 (129.7) 356 41 1.65
Rice + Dhaincha 1.61 (47.8) 381 52 1.97
CD (p=0.05) 0.02 9 3
Pretila 0.3 fb HW 1.63 (49.6) 413 57 2.21
2 HW 1.73 (58.9) 381 53 1.97
Unweeded 2.22 (178.1) 291 22 0.98
CD (p=0.05) 0.06 13 3
Ravisankar et al (2008) Coimbatore, T.N
Indian J Agron 53(1): 57-61
Weeds are one of major problem in DSR, reduces 5-95% yield
DSR is a labor-, fuel-, time-, and water-saving technology.
DSR is cost-effective and gives a higher net return than puddled
Weed management is critical in DSR, but with an different weed
management approach weeds can be managed.
There is a need to integrate different weed management strategies.
Use of a stale seedbed practice
Higher seed rate and quick growing varieties
Use of crop residue as mulches
Use of weed-competitive cultivars
Appropriate herbicide mixtures, timing,