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Crop Establishment

TropRice Entrance | Management Timetable | Land Preparation | Land LevelingIRRI Rice VarietiesCrop Establishment | Water Management | Nutrient Management | Weed Management | Insect Management | Disease Management | Snails, Rats & Birds  | Safe Application | Post-Production | EconomicsSeed Quality | Technology Changes  | Comments |

Table of Contents:

  1. Wet direct seeded
  2. Dry direct seeded
  3. Transplanted
  4. Replanting
  1. Other considerations
    1. Principles of crop establishment
    2. Factors affecting crop uniformity
    3. Pests during crop establishment
    4. Target plant stands
    5. How much seed do I need? 
    6. Disclaimer

This section on crop establishment assists farmers with decisions related to the initial sowing of the rice crop. Information on how to plant or seed (pre-germination, seeding depth, broadcasting, etc.) is provided for wet direct, dry direct and transplanted forms of crop establishment. Critical factors related to crop uniformity are also included along with how to control the major pests that appear during this time. Additional information regarding target plant stands, seed rates and replanting (to fill leftover gaps in the field) has also been provided.

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Crop establishment - Wet direct seeded

 

 

bulletNotes: Use CLEAN SEED - and increase yields by 5-20%!
bulletMajor issues for wet direct seeded crops are: 
bulletseed germination and emergence - Seed buried under mud or under mud and water has difficulty emerging.
bulletweed control.
bulletLand leveling and early water management, and
bulletPests during crop establishment
bulletPre-germinate seed
bullet48 hours before planting soak seed - change water every four hours if possible
bulletAfter 24 hours, incubate seed in the shade - rinse if possible to avoid seed becoming too hot
bulletSeeding depth
bulletTarget planting depth - <1cm If drilled - 0.5 cm (maximum 1 cm - Variety dependent)
bulletSurface seeding has fewer emergence problems than buried seed, but may have problems of birds and rats
bulletSoil tilth
bulletRule of thumb - the soil is ready for planting if a "V" made by dragging a stick through the prepared soil holds it's shape. If the soil is too wet, the "V" will collapse indicating the seed will likely sink too deep and have problems of emergence.
bulletSeeding
bulletWait 1-2 days after land preparation (depending on soil texture - see note immediately above) to avoid seed sinking too deep - deep seed will have problems emerging if covered by mud and water.
bulletBroadcast
bulletSeed rate - 80 to >120 kg seed/ha
bulletAnaerobically sow in rows
bulletSeed rate - 60-80 kg/ha
bulletSeed should not be planted deeper than 1 cm deep
bulletReplanting bare patches
bulletOne day after planting soak and incubate additional seed (e.g., 1 kg)
bulletAround three days after planting, broadcast additional seed in problem areas
bullet15 to 20 days after planting, transplant seedlings to bare patches, if required

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Crop establishment - Dry direct seeded

 

 

bulletNotes:
bulletUse CLEAN SEED - and increase yields by 5-20%!
bulletWeed pressure tends to be greater in dry direct seeded systems.
bulletDry direct seeding can use more water and fertilizer if there is no natural hardpan to limit infitration and percolation.
bulletSeeding depth
bulletTarget planting depth - <1cm If drilled - 0.5 cm (maximum 1 cm - Variety dependent)
bulletSurface seeding can have problems of birds and rats - Broadcast and harrow if possible
bulletSeed rate - 80 to >120 kg seed/ha
bulletOptions:
bulletBroadcast
bulletSeed rate - 80to >120 kg/ha
bulletBroadcast in furrows - modified California system
bulletSeed rate - 80 to >120 kg/ha
bulletPrepare land with furrows 15 cm apart and 5-10 cm deep - broadcast and harrow lightly - seeds will emerge fairly strongly in rows
bulletDrill seed in rows
bulletSeed rate - 60-80 kg/ha
bulletSeed should not be planted deeper than 1 cm deep
bulletReplanting bare patches
bulletSeeding bare patches - depends on soil moisture
bulletOne day after the field has sufficient moisture for germination, soak and incubate additional seed (e.g., 1 kg/ha)
bulletThree days after planting, broadcast additional seed in problem areas
bullet15 to 20 days after planting, transplant seedlings to bare patches

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Crop establishment - Transplanted

 

 

Use CLEAN SEED - and increase yields by 5-20%!

bulletManually plant
bulletPlant in rows - generally with a spacing of the order of 20 cm x 20 cm
bulletMechanically plant
bulletWait 1-2 days after land preparation to avoid plants sinking too deep - deep plants will have problems growing if covered by mud and water.
bulletReplanting bare patches
bullet15 to 20 days after planting, transplant seedlings to bare patches

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Factors affecting crop uniformity

 

 

For maximum yields, plant stand must be uniform across the field. The critical factors are:

bulletUniform seed and/or seedling distribution
bulletGood soil and water management - seeds will sink in soft soil and not emerge - or emerge unevenly
bulletGood land leveling
bulletGood water management, and
bulletGood control of pests during crop establishment 
bulletWith clay soils (like those at IRRI), wet direct seeding can have problems of emergence especially during the rainy season (rain seems to cause the seed to be buried deeper by the mud)
bulletSee Principles of crop establishment for more

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Principles

 

 

bulletGeneral goal: Establish a uniform plant stand
bulletTransplanting gives a stand
bulletDirect seeding, especially wet direct seeding, can be problematic.
bulletIf direct seed then
bulletneed more uniform land leveling and better water management
bulletseed planted too deep results in poor emergence and weak plants
bulletseed planted too shallow is susceptible to bird and rat attack
bulletSoil strength - For wet direct seeding, if the soil holds a shape after a stick is dragged through the mud, then the seed will not sink too deep. If the shape freely collapses, then the seed will likely sink too deep and have problems emerging.
bulletLodging can be reduced by transplanting (especially in the wet season), choice of variety, limiting N applications between PI and flowering, and reducing stem base diseases.
bulletCritical panicle numbers - For IRRI conditions, maximum yields require 500-600 panicles/m2 in the dry season and 350-400 panicles/m2 in the wet season for IR 72-type varieties.
bulletThe following tables summarize the principal considerations in moving from transplanting to direct seeding.

 

 

 

 

Wet direct seeded Dry direct seeded
No more nursery required No more nursery required
No more seedling pulling No more seedling pulling
Need to pre-germinate & incubate seed  
Need improved water management  
Need improved leveling  
Surface seed can be attacked by birds and rats Surface seed can be attacked by birds and rats
Weed more problematic Weed much more problematic
Seed planted too deep (>1cm) will have problems emerging  

Comparison of factors associated with different crop establishment methods

Table key: TP = Transplanted; MTP = Mechanically transplanted; DDS = Dry direct seeded; WDS = wet direct seeded (puddled soil); L= low, H = high; + = little problem; ++++ = major limitation

 

 

 

 

  TP MTP DDS WDS Comments
Cost L to H

H

L to H L to H Depends on labor markets
Land management          

Tillage

   

++

  Affects soil-seed contact

Land leveling

+

++++

+++

++++ Low spots typically have serious problems of snails and of emergence in direct seeding
Water management

+

+++

++

+++

Drainage is critical in direct seeding. Use small canals around or through the field

Leaching

   

++

  Greater problem if no puddling or subsoil compaction. Typically worse in dry direct seeded rice.
Pests          

Weed control

+

+

+++

++

Early seedling vigor and variety may decrease weeds through shading.

Red/weedy rice

   

+++

++

Can be reduced by water seeding (e.g., California) and use of good seed

Snails

++

++

 

+++

 

Rats & birds

   

++

++

 
Variety          

Lodging

++

++

+++

+++

Especially as N rates are increased

Early vigor

   

++

++

Especially for weed suppression

Seedling requirements

 

++

     

Pre-planting seed preparation

     

++

Pre-germination is required and this can be a problem if seeding is delayed
Soil factors          

Soil texture

+

++

++

+++

Affects emergence and development of anaerobic conditions

Soil-seed contact

   

+++

+

 

Depth to compaction layer

 

+++

 

++

Affects machine mobility - e.g., transplanter or seeder

Depth of planting

   

++

+++

Problem of anaerobic emergence
Rainfall during establishment    

+

+++

Effect worse on wet direct seeded and in heavier soils

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Target plant stands

 

 

Target plant stands are related to the target panicle counts. Target panicle counts are those that will give optimum yields. For example, panicles/m2 for maximum yield at IRRI (S Peng, pers. Comm.)

bulletDry season        Wet season
bullet500-600                  350-400

Tiller number is primarily driven by N management and plant stand.

Example: For a transplanted crop 2 plants/hill @ 20 cm spacing, there are (5 x 5 x 2) = 50 plants/m2. Thus, in the dry season each plant will need to produce 500/50=10 panicles/plant.

The following table shows the tillering required to attain target panicle counts from different initial crop stands.

 

 

 

 

 

Actual Plant Stand (/m2)

Plants/

Needed tillers/plant

10 x 10cm2

Dry season

Wet season

Broadcast

50

0.5

10-12

7-8

100

1

5-6

3.5-4

150

1.5

3.3-4

2.3-2.7

200

2

2.5-3

1.75-2

Plants/m row

Needed tillers/plant
Actual Plant Stand (/m2)

Row spacing (cm)

Dry season Wet season

15

20

25

Direct Seeded

50

7.5

10

12.5

10-12

7-8

100

15

20

25

5-6

3.5-4

150

22.5

30

37.5

3.3-4

2.3-2.7

200

30

40

50

2.5-3

1.75-2

Plants/50cm row

Needed tillers/plant
Actual Plant Stand (/m2)

Row spacing (cm)

Dry season Wet season

15

20

25

Direct Seeded

50

3.75

5

6.25

10-12

7-8

100

7.5

10

12.5

5-6

3.5-4

150

11.25

15

18.75

3.3-4

2.3-2.7

200

15

20

25

2.5-3

1.75-2

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Seed equivalents

 

 

Why is seed rate important?

See the section on target plant stands for more background on why crop stand is important.

An obvious way to manipulate crop stand is through seed rate. For example:

10 kg seed/ha = 400,000 seeds/ha = 40 seeds/m2 (@ a thousand grain weight of 25 g)

Often less than 50% of seeds emerge, thus in the above example, 10 kg would led to < 20 plants/m2.

In direct seeded fields, farmers sow anywhere between 65 and >200 kg seed/ha. Therefore if the target number of panicles/m2 are: 500-600 for the Dry season, and 350-400 for the Wet season:

 

 

 

 

 

Seed rate kg/ha

Seeds/m2

Probable Emergence

Tillers

Dry Season

Wet Season

60

240

<120

>4

>3

100

400

<200

>2.5

>1.8

140

640

<320

>1.6

>1.1

180

720

<360

>1.4

>1

220

880

<440

>1.1

<1

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Replanting (Filling gaps)

 

 

Transplanting

If TP, replant as soon as damage noted within 1 week of transplanting

Direct seeding

If DS, resow immediately that problem spots are noted, or transplant when seedlings around 5 cm (up to 2 weeks after planting).

If DS, pre-germinate additional seed 1-3 days after sowing field. Use this seed to fill in any gaps. Need some caution as herbicide applied may affect replanted spots.

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Disclaimer

To the best of our knowledge the material presented here is correct. However, IRRI and the authors are in no way responsible for the application, etc. of the chemicals or methods mentioned. They make no warranties, expressed or implied, as to the accurracy or adequacy of any of the information presented.