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Sub Topics
Principles of Crop Establishment
System of Rice Intensification (SRI)
Transplanting
Direct wet seeding
Direct dry seeding
Seedling Throwing Method

Crop Stand Establishment


Principles of Crop Establishment  
General goal:
  • Establish a uniform plant stand.
  • For maximum yield, plant stand must be uniform across the field.
  • Transplanting gives a good stand establishment
  • Direct seeding, especially wet direct seeding, may be problematic.
  • If direct seed then
  • i. Need more uniform land leveling and better water management
  • ii. Seed planted too deep results in poor emergence and weak plants

System of Rice Intensification (SRI)


Seed Rate
  • 7-8 kg/ha for transplanting single seedling per hill.
  • 12-15 kg/ha for transplanting two seedlings per hill wherever difficulty in establishment of rice is seen.
  • 15 days old seedlings are transplanted with 1-2 seedlings per hill.
  • Transplant within 30 minutes of pulling out of seedlings.

A commonly practiced methods are
  • Using  rope with marking
  • Using aluminium pipes with markings.
  • Using bamboo plank with pegs as markings
  • Using wooden marker
  • Using roller markers
  • Fill up the gaps between 7th and 10th DAT.
  • There may be difficulty in crop establishment in areas with heavy downpour (North East Monsoon periods of Tamil Nadu).

Transplanting :
     Transplanting consists of preparing seedlings in nursery and then planting these seedlings in the prepared main field. Transplanting ensures a uniform plant stand and gives the rice crop a head start over emerging weeds.
Seedling Management

Optimum age of seedlings for quick establishment   

      Optimum age of the seedlings for transplanting is 18-22 days for short duration, 25-30 days for medium duration and 35-40 days for long duration varieties.

Pulling out the seedlings
  • Pull out the seedlings at the appropriate time (4th leaf stage).
  • These seedlings can produce more tillers, provided enough care is given during the establishment phase by providing thin film of water and perfect levelled of main field.
  • Transplanting after 5th leaf and higher order leaf numbers will affect the performance of the crop and grain yield. They are called as ‘aged seedlings’.

Management of Aged seedlings
  • Follow the spacing recommended to medium and low fertility soil
  • Avoid cluster planting of aged seedlings, which are hindering the formation of new tillers.
  • To encourage the tiller production, enhance the basal N application by 50% from the recommended dose.  

Root dipping
  • Prepare the slurry with 5 packets (1000 g)/ha of Azospirillum and 5 packets (1000g/ha) of Phosphobacteria or 10 packets of (2000g/ha) of Azophos inoculant in 40 lit. of water and dip the root portion of the seedlings for 15 - 30 minutes in bacterial suspension and then transplant.

Plant Density and Spacing


In Tamil Nadu
Varietal duration
Low and Medium Fertility (plant/ha)
Spacing
(cm)

High Fertility
Plants / ha
Spacing
(cm)
Short 8 lakhs 12.5 x 10 5.0 lakhs 20x10
Medium 5.0 lakhs 20x10 3.3 lakhs 20x15
Long 3.3 lakhs 20x15 2.5 lakhs 20x20

In Kerala
Season Duration Spacing No.of hills/m2
First crop Medium
Short
20 cm x 15 cm
15 cm x 10 cm
33
67
Second crop

Medium
Short
20 cm x 10 cm
15 cm x 10 cm
50
67
Third crop Medium
Short
20 cm x 10 cm
15 cm x 10 cm
50
67

Optimum age of seedlings:

    Optimum age of the seedlings for transplanting is 18 days for short duration, 20-25 days for medium duration and 30 days for long duration varieties.

In Karnataka
  • Spacing: 20x10cm (50 hills/ sq.meter) 2-3 seedlings per hill
  • Short duration variety: 15x10cm (67 hills/ sq. meter)
  • In Tungabhadra command area, for transplanting of long duration varieties such as sona masuri under delayed condition (August 15-30th) select the seedlings which are 45 days old and transplant about 3 to 4 seedlings per hill to get higher yield.

Planting Seedling in the main field

Number of seedlings /hill
  • 2 to 4 seedlings / hill
  • Saline soil : 4 to 6 seedling / hill

Depth of Planting
  • Clay soil : 5 to 6 cm
  • Shallow soil : 2.5 to 3.0 cm
  • Shallow planting (3 cm) ensures quick establishment and more tillers.
  • Deeper planting (> 5cm) leads to delayed establishment and reduced tillers.

Transplanting shock:

  It occurs when the seedlings are pulled out from the nursery and planted in the new environment. For recovery from shock, it will take minimum of 5 to 7 days under tropics.

  • Shallow planting reduces the period.
  • Mild temperature after transplanting also reduces the period.
  • Hot and very cold weather delays recovery.
  • Best temperature: <30° C maximum and > 20° C minimum.

Gap filling
  • Fill the gaps, if any within 7 - 10 days after transplanting.

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Transplanting Methods  

Types
:
  • Manual transplanting
  • Machine transplanting

Manual transplanting

     Manual transplanting is most suited for labour-surplus areas and for small rice fields. Manual transplanting can be done in fields with less than optimal levelling and with varying water levels.

How to Transplant Rice Manually

  • Pull out the seedlings at an average of 15 to 30 days after seeding (DAS) from nurseries and transport them to the main field.
  • In a modified mat nursery, seedlings are ready for transplanting at 15-20 DAS and seedling mats are transported to main field.
  • Transplant the seedlings soon after pulling from the nursery in puddled, leveled field (any delay will lead to slow revival and even death of some seedlings).
  • Transplant 2-3 seedlings per hill at shallow depth at optimum spacing
    (20 cm x 20 cm or 22.5 cm x 22.5 cm).
  • Handle seedlings carefully to ensure their fast revival and rapid growth after transplanting.

Limitations :

  • Transplanting is tedious and time-consuming (up to 30 person-days ha-1).
  • Difficult to get enough labour at peak periods to plant on time.
  • Low plant density with contract transplanting on area basis lowers yields.
  • Risk, in rainfed areas, that seedlings (especially of modern varieties) may get too old before rain starts.








Machine transplanting

     Machine transplanting involves planting young rice seedlings into puddled soil by machine.

How to Transplant Rice by Machine?

  • Raise seedlings in special mat nurseries or in seedling trays. Use required quantity of good seed per 100 m2 of nursery for each ha.

  • Seedlings will be ready for transplanting in 12-15 days after seeding (DAS).
    Ensure that fields are well puddled and leveled.

  • Drain fields and allow mud to settle for 1-2 days after the final puddling.

  • The subsurface soil layers need to be hard enough to support the transplanting machine.

  • The soil is ready when a small “V” mark made in the puddled soil with a stick holds its shape. At this moisture level, the soil can hold the seedlings upright.

  • Soil should not be so dry that it sticks to and interferes with planting parts or wheels of the transplanter.

  • Load the seedling mats on the machine and transplant the seedlings at the selected machine setting.

Advantages

  • Machine transplanting requires considerably less time and labour than manual transplanting (1-2 ha/person/day versus 0.07 ha/person/day).
  • Fast and efficient (1-2 ha/day), and ensures timely planting.
  • Reduces stress, drudgery and health risks.
  • Ensures uniform spacing and plant density.
  • Seedlings recover fast, tiller vigorously, and mature uniformly.


Limitations

  • Seedlings must be planted while still young, and so mechanical transplanting is best suited for irrigated areas only.
  • Special nursery management is needed (mat nursery or seedling trays).
  • Good land preparation, leveling and water management are required.






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Direct Wet Seeding
  • Seed rate – 60 kg/ha.
  • Pre germinate the seeds as for wet nursery.
  • Sow the seeds by drum seeder or broadcast uniformly with thin jfilm of water.
    Thinning and gap filling should be done 14-21 days after sowing.
  • Dual cropping of rice-green manure is economic for nutrient budget and efficient for grain production. For this method use ‘TNAU Rice-Green manure seeder’.
  • If dual cropped with green manure, incorporate the green manure when grown to 40cm height or at 30 days after sowing, whichever is earlier, using Cono-weeder.
  • Green manure incorporated fields may be operated again with rotary weeder a week later in order to aerate the soil and to exploit organic acids formed if any.

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Direct Dry Seeding  

In Tamil Nadu
:
  • Seed rate: 75 kg/ha dry seed for any recommended variety.
  • Seed hardening with 1% KCl for 16 hours (seed and KCl solution 1:1) and shade dried to bring to storable moisture. This will enable the crop to withstand early moisture stress.
  • On the day of sowing, treat the hardened seeds first with Pseudomonas fluroscens 10g/kg of seed and then with Azophos 2000 g or Azospirillum and Phosphobacteria @ 600 g each per ha seed, whichever is available.
  • Drill sow with 20 cm inter row spacing using seed drill.

In Kerala :
  • Seed rate
    Broadcasting            80-100 kg/ha
    Dibbling                    80-90 kg/ha
    [Note: The above seed rates are specified for farmers' field on the basis of minimum germination of 80%. In pokkali cultivation, for Vyttila varieties, 100 kg/ha may be sown on the beds or mounds formed in the field.

In Karnataka :
  • Seed rate – 100 kg/ha
  • Possible to obtain higher yields with direct sowing of rice.
  • Direct sowing of rice is preferred to transplanting rice in areas with low water availability.
  • Direct seeding is a viable option in areas with shortage of water and labour.
  • Large scale adoption of direct sowing is possible.

Sowing of Paddy using drum seeder :
  • Followed under late sown conditions especially in the month of July when rainfall is sufficient enough to make puddling.
  • Use pre-germinated seeds for sowing
  • Seed rate - 40 kg/ha






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Seedling Throwing Method
  • 20 days old seedlings of short duration rice varieties.
  • Requirement of seedlings will be approximately 20% more than the line planting or equal to random planting.
  • The seedlings are thrown into the puddled leveled field by labour without using force.
  • Suitable for all seasons except Thaladi or heavy rain season.
  • 50% labour shaving as compared to line planting and 35% to random planting.
  • Up to 7-10 days of seedling throwing care should be taken to maintain thin film of water
    (similar to wet seeded rice).
  • Other cultural operations are same as transplanted rice.
  • Grain yield will be equal to line planted crop and 10-12% higher than random planted crop.

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